Stereoisomeric separation of the chiral herbicide profoxydim and residue method development in rice by QuEChERS and LC-MS/MS

A method for the simultaneous determination of the four stereoisomers of the chiral herbicide profoxydim in rice and husk was developed using the QuEChERS method and LC-tandem mass spectrometry. Four polysaccharide-based chiral stationary phase columns were evaluated. All four stereoisomers were successfully separated on a Chiracel OJ-3R column. The effects of mobile phase, modifiers, mobile phase flow rate and temperature on the separation were also investigated. Different QuEChERS methods were compared for the development of an optimized sample preparation procedure. The method, following SANTE guidelines, showed excellent linearity (R2 ≥ 0.99), the LODs were below 4.0 µg kg-1, and the LOQs did not exceed 12.5 µg kg-1. The overall average recoveries at three levels (12.5, 25.0 and 250 µg kg-1) ranged from 76.77 % to 106.53 %, with RSD values less than 7 %. The method is demonstrated to be convenient and reliable for the routine monitoring of profoxydim stereoisomers in rice and husk.

Pharmacokinetic study of multicomponent in Hong-Hua-Xiao-Yao tablet

Hong-Hua-Xiao-Yao tablet (HHXYT) is attracting attention increasingly because of its use in treatment of mammary gland hyperplasia (MGH) and menopausal syndrome. However, its pharmacokinetics remains unclear. This study developed a sensitive and rapid method for simultaneous determination of 10 compounds of HHXYT in rat plasma by liquid chromatography-tandem mass spectrometry and to compare the pharmacokinetics of these compounds in MGH rats and sham operated rats. The linearity, accuracy, precision, stability and matrix effect were within acceptable ranges. This established method was successfully applied to a pharmacokinetics study of 10 compounds in sham operated and MGH rats. According to the results, the bioavailability of glycyrrhetinic acid was highest in MGH rats and sham operated rats. The mean residence times of glycyrrhetinic acid and glycyrrhetinic acid 3-O-glucuronide were higher than those of the other compounds while the mean residence time and half-life of liquiritin, isoliquiritin and paeoniflorin were lower. Some pharmacokinetic parameters of ormononetin, liquiritigenin, isoliquiritigenin, liquiritin, isoliquiritin, paeoniflorin, protocatechuic acid and senkyunolide I were significantly different between MGH rats and sham operated rats. This study elucidated the dynamic changes of multiple components in rats after oral administration of HHXYT systematically and comprehensively, which provided guidance for clinical application.

Method development for the quantification of nine nitazene analogs and brorphine in Dried Blood Spots utilizing liquid chromatography - tandem mass spectrometry

The detection of nitazenes in biological fluids is increasingly needed as they are repeatedly reported in intoxication and overdose cases. A simple method for the quantification of low levels of nine nitazene analogs and brorphine in Dried Blood Spots (DBS) was developed and validated. 10 μL of spiked whole blood is deposited on a Capitainer®B card and allowed to dry. The spot is punched out, and extracted with 500 μL methanol:acetonitrile (3:1 v/v) added with 1.5 μL of fentanyl-D5 as the internal standard. After stirring, sonication, and centrifugation of the vial, the solvent is dried under nitrogen, the extract is reconstituted in 30 μL methanol, and 1 μL is injected into a UHPLC-MS/MS instrument. The method validation showed linear calibration in the 1-50 ng/mL range, LOD values ranging between 0.3 ng/mL (isotonitazene) and 0.5 ng/mL (brorphine), average CV% and bias% within 15 % and 10 % for all compounds, respectively. The matrix effect due to blood and filter paper components was within 85-115 % while recovery was between 15-20 %. Stability tests against time and temperature showed no significant variations for storage periods up to 28 days. Room temperature proved to represent the best samples storage conditions. UHPLC-MS/MS proved capable to reliably identify all target analytes at low concentration even in small specimen volumes, as those obtained from DBS cards, which in turn confirmed to be effective and sustainable micro-sampling devices. This procedure improves the efficiency of toxicological testing and provides an innovative approach for the identification of the nitazene class of illicit compounds.

Tetrodotoxins in Tissues and Cells of Different Body Regions of Ribbon Worms Kulikovia alborostrata and K. manchenkoi from Spokoynaya Bay, Sea of Japan

Nemerteans, or ribbon worms, possess tetrodotoxin and its analogues (TTXs), neurotoxins of bacterial origin, which they presumably use for capturing prey and self-defense. Most TTXs-containing nemertean species have low levels of these toxins and, therefore, have usually been neglected in studies of TTXs functions and accumulation. In the present study, Kulikovia alborostrata and K. manchenkoi, two closely related species, were analyzed for TTXs distribution in the body using the HPLC-MS/MS and fluorescence microscopy methods. The abundance of TTXs-positive cells was determined in the proboscis, integument, and digestive system epithelium. As a result, six TTXs-positive cell types were identified in each species; however, only four were common. Moreover, the proportions of the toxins in different body parts were estimated. According to the HPLC-MS/MS analysis, the TTXs concentrations in K. alborostrata varied from 0.91 ng/g in the proboscis to 5.52 ng/g in the precerebral region; in K. manchenkoi, the concentrations ranged from 7.47 ng/g in the proboscis to 72.32 ng/g in the posterior body region. The differences observed between the two nemerteans in the distribution of the TTXs were consistent with the differences in the localization of TTXs-positive cells. In addition, TTXs-positive glandular cell types were found in the intestine and characterized for the first time. TTXs in the new cell types were assumed to play a unique physiological role for nemerteans.

Analytical methods based on liquid chromatography for the analysis of albumin adducts involved in retrospective biomonitoring of exposure to mustard agents

The objective of the present review is to list, describe, compare, and critically analyze the main procedures developed in the last 20 years for the analysis of digested alkylated peptides, resulting from the adduction of albumin by different mustard agents, and that can be used as biomarkers of exposure to these chemical agents. While many biomarkers of sulfur mustard, its analogues, and nitrogen mustards can easily be collected in urine such as their hydrolysis products, albumin adducts require blood or plasma collection to be analyzed. Nonetheless, albumin adducts offer a wider period of detectability in human exposed patients than urine found biomarkers with detection up to 25 days after exposure to the chemical agent. The detection of these digested alkylated peptides of adducted albumin constitutes unambiguous proof of exposure. However, their determination, especially when they are present at very low concentration levels, can be very difficult due to the complexity of the biological matrices. Therefore, numerous sample preparation procedures to extract albumin and to recover alkylated peptides after a digestion step using enzymes have been proposed prior to the analysis of the targeted peptides by liquid chromatography coupled to mass spectrometry method with or without derivatization step. This review describes and compares the numerous procedures including a number of different steps for the extraction and purification of adducted albumin and its digested peptides described in the literature to achieve detection limits for biological samples exposed to sulfur mustard, its analogues, and nitrogen mustards in the ng/mL range.

A validated LC-MS/MS method for determination of six Anti-SARS-CoV-2 drugs in plasma and its application for a pharmacokinetic study in rats

Antiviral treatment for COVID-19 is considered an effective tool in reducing the rate of severe cases and deaths. As of June 2023, a total of six small molecule antiviral drugs have been conditionally approved for marketing by the National Medical Products Administration (NMPA) within China. In this study, a method of HPLC-MS/MS was established and validated for the determination of six small molecule antiviral drugs in plasma using Lamivudine as an internal standard. The chromatographic separation was performed using gradient elution with an ACE 3 C18-PFP column (3.0 mm × 150 mm, 3 μm), and the mobile phase consisted of deionized water and acetonitrile/water (90:10, v/v), both with 10 mmol/L of ammonium acetate and 0.1 % ammonium hydroxide added. Quantitative analysis of the six small molecule drugs was carried out through selective reaction monitoring based on the positive ion spray ionization mode. The method exhibited excellent precision, accuracy, recovery, and linearity, and it was used to determine the pharmacokinetic characteristics in rats. Our work not only established a bioanalytical method for six small molecule antiviral drugs but also provided scientific references for clinical pharmacokinetic studies.

A liquid chromatography-mass spectrometry method for the enantioselective multiresidue determination of nine chiral agrochemicals in urine using an enrichment procedure based on graphitized carbon black

Many agrochemicals are chiral molecules, and most of them are marketed as racemates or diastereomeric mixtures. Stereoisomers that are not the active enantiomer have little or no pesticidal activity and can exert serious toxic effects towards non-target organisms. Thus, investigating the possible exposure to different isomers of chiral pesticides is an urgent need. The present work was aimed at developing a new enantioselective high-performance liquid chromatography-mass spectrometry method for the simultaneous determination of nine chiral pesticides in urine. Two solid-phase extraction (SPE) procedures, based on different carbon-based sorbents (graphitized carbon black (GCB) and buckypaper (BP)), were developed and compared. By using GCB, all analytes were recovered with yields ranging from 60 to 97%, while BP allowed recoveries greater than 54% for all pesticides except those with acid characteristics. Baseline separation was achieved for the enantiomers of all target agrochemicals on a Lux Cellulose-2 column within 24 min under reversed-phase mode. The developed method was then validated according to the FDA guidelines for bioanalytical methods. Besides recovery, the other evaluated parameters were precision (7-15%), limits of detection (0.26-2.21 µg/L), lower limits of quantitation (0.43-3.68 µg/L), linear dynamic range, and sensitivity. Finally, the validated method was applied to verify the occurrence of the pesticide enantiomers in urine samples from occupationally exposed workers.

Tetrodotoxin and Its Analogues (TTXs) in the Food-Capture and Defense Organs of the Palaeonemertean Cephalothrix cf. simula

Tetrodotoxin (TTX), an extremely potent low-molecular-weight neurotoxin, is widespread among marine animals including ribbon worms (Nemertea). Previously, studies on the highly toxic palaeonemertean Cephalothrix cf. simula showed that toxin-positive structures are present all over its body and are mainly associated with glandular cells and epithelial tissues. The highest TTXs concentrations were detected in a total extract from the intestine of the anterior part of the body and also in a total extract from the proboscis. However, many questions as to the TTXs distribution in the organs of the anterior part of the worm's body and the functions of the toxins in these organs are still unanswered. In the present report, we provide additional results of a detailed and comprehensive analysis of TTXs distribution in the nemertean's proboscis, buccal cavity, and cephalic gland using an integrated approach including high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), confocal laser scanning microscopy with anti-TTX antibodies, light and electron microscopies, and observations of feeding behavior. For the proboscis, we have found a TTXs profile different from that characteristic of other organs and tissues. We have also shown for the first time that the major amount of TTXs is localized in the anterior part of the proboscis that is mainly involved in hunting. TTX-containing glandular cells, which can be involved in the prey immobilization, have been found in the buccal cavities of the nemerteans. A significant contribution of the cephalic gland to the toxicity of this animal has been shown for the first time, and the role of the gland is hypothesized to be involved not only in protection against potential enemies but also in immobilizing prey. The data obtained have made it possible to extend the understanding of the role and features of the use of TTXs in the organs of the anterior part of nemertean's body.

Development, validation, and implementation of an ultratrace analysis method for the determination of moenomycin A, in aquatic animal products

Moenomycin A, an antimicrobial growth promoter widely used as an additive in aquaculture feedstuffs, has been restricted for use in the European Union and China due to its potential risk of promoting resistant strains of pathogenic bacteria and causing residues in aquatic animal products. Although methods for analyzing moenomycin A in feedstuffs have been developed, no established method exists for aquatic matrices. In this study, we present, for the first time, a sensitive and validated high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for the determination of moenomycin A in aquatic animal products. Samples were extracted using methanol and purified with the QuEChERS method employing C18 sorbent. The aliquot was dried under a nitrogen stream, reconstituted with methanol-water solvent, and analyzed by HPLC-MS/MS. The developed method exhibited good linearity (r2 > 0.995) over a wide concentration range (1-100 μg/L) and a low limit of detection (1 µg/kg). Average recoveries ranged between 70 and 110% at spiked concentrations of 1, 50, and 100 μg/kg, with associated intra- and inter-day relative standard deviations of 1.25 to 7.32% (n = 6) and 2.91 to 10.08% (n = 3), for different representative aquatic animal production, respectively. To the best of our knowledge, this is the first reported HPLC-MS/MS method for the quantification of moenomycin A in aquatic animal products. The new approach was effectively employed in the analysis of moenomycin A across various aquatic samples.

Mass Balance Studies of Robenidine Hydrochloride in the Body of Channel Catfish (Ictalurus punctatus)

This study aims to determine the mass balance of robenidine hydrochloride (ROBH) in the body of Channel catfish (Ictalurus punctatus). ROBH was administered orally at a dose of 20 mg/kg; following drug administration, the water samples were collected at predetermined time points (12, 24, 48, 72, 96, 120, 144, and 168 h), the experimental fish were executed after the water samples were obtained at 168 h, and the tissue samples were collected separately from the bones. The water and tissue samples were analyzed by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) for concentrations of ROBH and its potential major metabolites, 4-chlorohippuric acid (PCHA) and 4-chlorobenzoic acid (PCBA). The tissue samples were prepared using a modified QuEChERS procedure; the water samples were prepared using a liquid-liquid extraction (LLE) procedure. The results show that the recovery rate of ROBH in fish is very low, less than 2% of the total amount of the drug, and the recovery in water can reach 80.7% of the total amount of the drug. The content of PCBA accounted for 42.4% of the total amount of the drug; the content of ROBH accounted for 38.3% of the total amount of the drug. The content of PCHA accounted for less than 1% of the total amount of the drug. The results show that, after a single administration, ROBH is rapidly metabolized in vivo and excreted in the form of ROBH as well as metabolite PCBA. ROBH and PCBA can be used as the main targets for the metabolism detection of ROBH in Channel catfish.

Comparative metabolism of aflatoxin B1 in mouse, rat and human primary hepatocytes using HPLC-MS/MS

Aflatoxin B1 (AFB1) is a highly hepatotoxic and carcinogenic mycotoxin produced by Aspergillus species. The compound is mainly metabolized in the liver and its metabolism varies between species. The present study quantified relevant AFB1- metabolites formed by mouse, rat, and human primary hepatocytes after treatment with 1 µM and 10 µM AFB1. The use of liquid chromatographic separation coupled with tandem mass spectrometric detection enabled the selective and sensitive determination of phase I and phase II metabolites of AFB1 over incubation times of up to 24 h. The binding of AFB1 to macromolecules was also considered. The fastest metabolism of AFB1 was observed in mouse hepatocytes which formed aflatoxin P1 as a major metabolite and also its glucuronidated form, while AFP1 occurred only in traces in the other species. Aflatoxin M1 was formed in all species and was, together with aflatoxin Q1 and aflatoxicol, the main metabolite in human cells. Effective epoxidation led to high amounts of DNA adducts already 30 min post-treatment, especially in rat hepatocytes. Lower levels of DNA adducts and fast DNA repair were found in mouse hepatocytes. Also, protein adducts arising from reactive intermediates were formed rapidly in all three species. Detoxification via glutathione conjugation and subsequent formation of the N-acetylcysteine derivative appeared to be similar in mice and in rats and strongly differed from human hepatocytes which did not form these metabolites at all. The use of qualitative reference material of a multitude of metabolites and the comparison of hepatocyte metabolism in three species using advanced methods enabled considerations on toxification and detoxification mechanisms of AFB1. In addition to glutathione conjugation, phase I metabolism is strongly involved in the detoxification of AFB1.

Occurrence and Health Risk Assessment of Sulfonamide Antibiotics in Different Freshwater Fish in Northeast China

This study aimed to investigate the levels of 12 sulfonamide antibiotics in freshwater fish species obtained from three cities in northeastern China (Harbin, Changchun, and Shenyang). The analysis was conducted using HPLC-MS/MS to accurately quantify the antibiotic concentrations in the fish samples. The results showed that the average levels of sulfonamide antibiotics in fish samples from Harbin, Changchun, and Shenyang were 1.83 ng/g ww, 0.98 ng/g ww, and 1.60 ng/g ww, respectively. Sulfamethoxazole displayed the highest levels and detection rates in all three cities, whereas sulphapyridine exhibited the lowest concentrations in all the fish samples. The levels of sulfonamide antibiotic residues in the different fish species varied widely among the cities, and the highest level of antibiotic residues was found in the muscle of carnivorous fish. The results from a health risk evaluation on the consumption of these fish indicated that the risk from long-term antibiotic exposure to local residents from the intake of the sampled fish was small and not sufficient to pose a significant health risk to consumers.

Analysis of tigecycline in the cerebrospinal fluid and serum of patients with Acinetobacter baumannii central nervous system infection

Aim: This study aimed to establish a method to determine tigecycline (TGC) in the cerebrospinal fluid (CSF) and serum of 12 patients with multidrug-resistant Acinetobacter baumannii (MDRAB) central nervous system infection (CNSI) and evaluate the correlation of TGC in CSF and serum samples. Materials & methods: TGC in CSF and serum was detected by high-performance liquid chromatography with tandem mass spectrometry. Results: In all 12 patients, the CSF-to-serum ratio of TGC at a steady-state trough concentration ranged from 21.46 to 44.46%, and the mean value was 31.61 ± 8.13%. The correlation of TGC in CSF and serum was 0.5065. Conclusion: CNSI might have no potential to increase the penetration ability of TGC into the CSF. The correlation between the concentrations of TGC in CSF and serum at steady state was demonstrated to be positive.

Evaluation of Tropane Alkaloids in Teas and Herbal Infusions: Effect of Brewing Time and Temperature on Atropine and Scopolamine Content

Atropine and scopolamine belong to the tropane alkaloid (TA) family of natural toxins. They can contaminate teas and herbal teas and appear in infusions. Therefore, this study focused on analyzing atropine and scopolamine in 33 samples of tea and herbal tea infusions purchased in Spain and Portugal to determine the presence of these compounds in infusions brewed at 97 °C for 5 min. A rapid microextraction technique (µSPEed^®) followed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used to analyze the selected TAs. The results showed that 64% of the analyzed samples were contaminated by one or both toxins. White and green teas were generally more contaminated than black and other herbal teas. Of the 21 contaminated samples, 15 had concentrations above the maximum limit for liquid herbal infusions (0.2 ng/mL) set by Commission Regulation (EU) 2021/1408. In addition, the effects of heating conditions (time and temperature) on atropine and scopolamine standards and naturally contaminated samples of white, green, and black teas were evaluated. The results showed that at the concentrations studied (0.2 and 4 ng/mL), there was no degradation in the standard solutions. Brewing with boiling water (decoction) for 5 and 10 min allowed for higher extraction of TAs from dry tea to infusion water.

Simultaneous determination of four antibiotics in human plasma by high-performance LC-MS/MS: application to therapeutic drug monitoring

Background: Aimed to simultaneously measure linezolid, voriconazole, cefoperazone and fluconazole in human plasma suitable for therapeutic drug monitoring applications, a robust, rapid and easy-to-use HPLC-MS/MS approach was developed and validated. Materials & methods: Protein precipitation was used to prepare analytes from 100 μl plasma. HPLC was employed for analyte separation, and quantification was conducted via multiple reaction monitoring in positive ion mode. The methodology was fully validated. Results & conclusion: All four antibiotics were found to be stable under the tested conditions, and accuracy values ranged from 90.96 to 113.25% and CV values were <14.0%. This HPLC-MS/MS method can be used for routine clinical therapeutic drug monitoring of linezolid, voriconazole, cefoperazone and fluconazole simultaneously.

Comparison of pharmacokinetic profiles in hypoalbuminemia and healthy rats after parecoxib sodium injection by LC-MS/MS

Background: Valdecoxib is an active metabolite of parecoxib that has a high binding rate with plasma protein. Hypoalbuminemia may affect the pharmacokinetics process of valdecoxib. Method & results: A rapid LC-MS/MS method was applied to assay parecoxib and valdecoxib in hypoalbuminemia and healthy rats. Hypoalbuminemia rat models were established by intravenous injection of doxorubicin. The maximum plasma concentration and area under the curve values of valdecoxib in control and model groups were 744.04 ± 128.24 ng/ml, 152,727.87 ± 39,131.36 ng/ml·min and 234.25 ± 77.36 ng/ml, 29,032.42 ± 5116.62 ng/ml·min after 7.2 mg/kg parecoxib sodium injection and 371.95 ± 64.12 ng/ml, 62,218.25 ± 6876.93 ng/ml·min and 153.41 ± 33.17 ng/ml, 18,245.62 ± 868.53 ng/ml·min after 3.6 mg/kg parecoxib sodium injection, respectively. Conclusion: Hypoalbuminemia increases clearance and reduces the plasma concentration of valdecoxib in rats.

Degradation and residues of mandipropamid in soil and ginseng and dietary risk assessment in Chinese culture

Mandipropamid, a new fungicide for oomycete disease, has a strong effect on the blight of many crops and has been registered for the treatment of ginseng blight in China. However, no maximum residue limit (MRL) of mandipropamid has been identified for ginseng, and there have been few related studies. We established and verified the analysis method of mandipropamid in ginseng using high-performance liquid chromatography-tandem mass spectrometry. The method has good linearity and accuracy in the range of 0.002-0.5 mg/kg. The average recovery of mandipropamid was 87.4-101.6%, and the standard deviation was 1.1-4.0. Mandipropamid in ginseng plants and soil rapidly degraded following first-order kinetics models. The degradation dynamics showed that the half-life of mandipropamid in ginseng plant and soil was 13.8-28.0 and 9.8-27.4 d, respectively. After the recommended dose of mandipropamid was applied once, the residual content of mandipropamid in fresh ginseng, dried ginseng, red ginseng, ginseng plant, and ginseng soil was < 0.01-0.185, < 0.01-0.265, 0.085-1.544, 0.075-4.800, and < 0.01-0.014 mg/kg, respectively. The dietary risk assessment of mandipropamid on ginseng showed that the risk quotient value was far less than 100%, indicating that the recommended dose of mandipropamid does not cause unacceptable risks to humans. After the recommended dose of mandipropamid was applied once, it did not cause unacceptable risks to humans. This study not only provides a reasonable spray dosage of mandipropamid to ginseng but also offers a reference for the establishment of MRLs in China.

The Quantification of Paclitaxel and Its Two Major Metabolites in Biological Samples by HPLC-MS/MS and Its Application in a Pharmacokinetic and Tumor Distribution Study in Xenograft Nude Mouse

A rapid and sensitive high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the quantification of Paclitaxel (PTX), 6α-hydroxypaclitaxel (6α-OHP), and p-3'-hydroxypaclitaxel (3'-OHP) in mouse plasma and tumor tissue. The analytes were separated using a C18 column (50 × 2.1 mm, 1.8 μm), and a triple-quadrupole mass spectrometry device equipped with an electrospray ionization (ESI) source was applied for their detection. PTX, 6α-OHP, and 3'-OHP were extracted from the biological samples with the solid-phase extraction cartridge. The method was fully validated according to the FDA's guidance. The method was linear over the concentration ranges of 0.5~1000.0 ng/mL for PTX and 0.25~500.0 ng/mL for 6α-OHP and 3'-OHP. The precision, accuracy, extraction recovery, and matrix effects were within acceptable limits. The present method was successfully applied to the study of the pharmacokinetics and distribution of PTX, 6α-OHP, and 3'-OHP in the tumors of post xenograft nude mice intravenously injected with PTX solution.

Tetrodotoxins in Ribbon Worms Cephalothrix cf. simula and Kulikovia alborostrata from Peter the Great Bay, Sea of Japan

Tetrodotoxin, an extremely potent low-molecular-weight neurotoxin, and its analogues (TTXs) are widely distributed in aquatic and terrestrial ecosystems. Most investigations concerning TTXs have been conducted mainly on puffer fish, octopus, and mollusks, without paying due attention to various non-edible animals including nemerteans, a small group of marine worms, several species of which have been shown to possess high amounts of TTXs. In this study, for the first time, variations in TTX and its analogues, in 32 specimens of Cephalothrix cf. simula and 36 specimens of Kulikovia alborostrata, from Peter the Great Bay Sea of Japan were investigated, which may contribute to elucidation of TTXs migration pathways in ecosystems. Using high performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS), it was found that the total TTXs concentrations within both species vary by one to several orders of magnitude, 85.75-7108.26 µg/g and 0.35-8.11 ng/g in C. cf. simula and K. alborostrata, respectively. The intra- and interspecies similarities in proportions of TTXs in both species were observed; based on the results, a possible way of their toxification was discussed.

Identification and Quantification of 29 Active Substances by HPLC-ESI-MS/MS in Lyophilized Swine Manure Samples

Veterinary drugs are frequently employed to treat and prevent diseases in food-producing animals to improve animal health and to avoid the introduction of microorganisms into the food chain. The analysis of the presence of pharmaceutical residues in animal manure could help to evaluate the legal and illegal practices during food production without harming the animals and to correctly manage manure when it is going to be applied as a fertilizer. This article describes a method for the simultaneous analysis of 29 active substances, mostly antibiotics and antiparasitic agents. Substances were extracted from lyophilized manure with a methanol:McIlvaine solution and analyzed with HPLC-ESI-MS/MS and a C18 HPLC column. The method was validated following European guidelines, the achieved trueness was between 63 and 128% (depending on the analytes), and the linearity was between 100 and 1500 µg/kg. The applicability of the method was demonstrated in 40 manure samples collected from pig farms where tetracycline was quantified in 7.5% of the samples. These results show the viability of this non-invasive method for the control of the legal and illegal administration of pharmaceuticals in food-producing animals.

Pharmacokinetics and pharmacodynamics of bioactive compounds in Penyanqing preparation in THP-1 inflammatory cells induced by Lipopolysaccharide

BACKGROUND

Penyanqing (PYQ), a traditional Chinese medicine (TCM), has a good clinical efficacy for the treatment of pelvic inflammatory disease (PID). Previously, researches on its anti-inflammatory effect and mechanism in vitro, in silico, and in vivo have been reported by our team. However, the interrelationship between the anti-inflammatory activity and the active compounds in PYQ are not clear. Here, the pharmacokinetics-pharmacodynamics (PK-PD) study was carried out for more proper clinical use.

METHODS

The plasma concentrations of salvianolic acid B (SAB), protocatechualdehyde (PRO), paeoniflorin (PE), astilbin (AST), ferulic acid (FE), and chlorogenic acid (CH) in SD rats after PYQ administration were determined by a selective and rapid HPLC-MS/MS method. In addition, the PK-PD on cell model was used to explore the relationship between the plasma concentration and inflammatory biomarkers (TNF-α, IL-1β).

RESULTS

The results of this study showed that the six components could reach the peak blood concentration within 0.29 h, indicating the rapid absorption of it. The eliminations of AST, CH, FE, PE, and PRO were relatively fast due to their mean residence times (MRTs) within 3 h, while the elimination of SAB was slower (MRT 5.67 ± 0.66 h). Combined with a THP-1 cell model, there was a significant correlation between inflammatory factors and component plasma concentrations with correlation coefficients in the range of -0.9--0.746. Correspondingly, the drug-containing plasma obtained at 0.25 h point exhibited the best inhibition effect on production of IL-1β and TNF-α in LPS-induced THP-1 cells.

CONCLUSION

The six main components in PYQ could be quickly absorbed, and there was a potential good correlation between their pharmacokinetics and the pharmacodynamics of PYQ.

Highly Sensitive Determination of Antibiotic Residues in Aquatic Products by High-Performance Liquid Chromatography-Tandem Mass Spectrometry

Antibiotic drug residues are crucial to ensure food safety and minimize risk to human health. Herein, a sensitive high-performance liquid chromatography−tandem mass spectrometry (HPLC−MS/MS) method was developed and validated for the determination of antibiotic residues (mainly amphenicols) consisting of chloramphenicol (CAP), thiamphenicol (TAP), florfenicol (FF), and florfenicol amine (FFA) in aquatic products. Amphenicols were well separated on a Kinetex F5 (100 mm × 3.0 mm, 2.6 µm) chromatographic column with the mobile phases of 1 mM ammonium acetate aqueous solution and methanol solution and measured after positive and negative electrospray ionizations using four internal standards. To our knowledge, it was the first time to report the good performance of F5 column and four internal standards for the determination of amphenicols. The established method featured a good linear relationship between chromatographic peak area ratios and the concentrations of amphenicols (R2 > 0.992), a wide and low detection matrix-based range of 0.01−5 μg/L, a low detection limit of 0.01 μg/kg, etc. The spiked assays evidenced the accuracy and reliability of the developed method with the recoveries between 84.0 and 105%, the intraday relative standard deviations (RSDs) over the range of 0.769−13.7%, and the interday RSDs over the range of 0.582−13.3%. Finally, the proposed method was applied to investigate amphenicol residues in various aquatic products, including fish, shrimp, crab, shellfish, and other aquatic species.

Selection of Potential Probiotic Yeasts from Dry-Cured Xuanwei Ham and Identification of Yeast-Derived Antioxidant Peptides

The aim of this study was to select potential probiotic yeasts from dry-cured Xuanwei ham and investigate yeast-derived antioxidant peptides. The results showed that two strains (XHY69 and XHY79) were selected as potential probiotic yeasts and identified as Yamadazyma triangularis. The two yeasts showed tolerance under pH 2.5 and 1% bile salt, in addition to protease activity, auto-aggregation, antibacterial, and antioxidant activities. The peptide fraction (MW < 3 kDa) isolated from XHY69 fermentation broth, named XHY69AP, showed higher radical scavenging activities than glutathione at a concentration of 4.5 mg/mL (p < 0.05). The fraction (AP-D10) was purified from XHY69AP by gel filtration chromatography and reversed-phase high performance liquid chromatography, and then further identified by a UHPLC-LTQ-Orbitrap mass spectrometer. The molecular weight of all 55 purified sequences was distributed between 0.370 and 0.735 kDa. Among these seven novel peptides, Tyr-Pro-Leu-Pro (YPLP), Ala-Gly-Pro-Leu (AGPL), Gly-Pro-Phe-Pro (GPFP), and Ala-Pro-Gly-Gly-Phe (APGGF) were identified. All sequences were abundant in hydrophobic amino acids, especially proline residue. Among these novel peptides, YPLP possessed the highest ABTS scavenging rate (75.48%). The present work selects two new probiotic potential yeasts from dry-cured Xuanwei ham that are effective to yield novel antioxidant peptides.

HPLC-MS/MS analysis of zinc-thiazole residues in foods of plant origin by a modified derivatization-QueChERS method

Zinc-thiazole is a new fungicide that was independently developed in China and has a high efficiency and low toxicity. A modified derivatization method was established to measure zinc-thiazole in foods of plant origin. Zinc-thiazole decomposed into 2-amino-5-mercapto-1,3,4-thiadiazole (AMT) under alkaline conditions, and the AMT was extracted with acidic acetonitrile (pH = 3). The AMT was quantitated by HPLC-MS/MS, and then the amount of zinc-thiazole residue was calculated. Good linearity (R² > 0.9997) was obtained in 0.001-1 mg/L. The limit of quantification of zinc-thiazole was 0.02 mg/kg in peaches, grapes, brown rice and soybeans. A qualified accuracy (recoveries of 75%-90%) and precision (RSD of 1%-5%) were obtained at three fortified levels. This method was applied to peach samples collected from farmland, and the zinc-thiazole residues complied with the residue limits. In the future, this method could be used to analyze residues and in the risk assessment of metal-thiazole fungicides.

New Residue Analysis Method for Four Task-Specific Ionic Liquids in Water, Soil and Plants

With the extensive application of task-specific ionic liquids (TSILs), their environmental impact has attracted increasing attention. However, no studies involving residue analyses of TSILs have been reported in the literature thus far. In the present study, residues of four TSILs ([C₂NH₂MIm]BF₄, [HOEMIm]BF₄, [HOEMIm]NO₃, [MOEMIm]BF₄) were analyzed by high-performance liquid chromatography-tandem mass spectrometry. The limit of detection of instrument was approximately 10^-15 g. Residual TSILs were extracted from soil and plant samples by the accelerated solvent extraction method. In water, soil and plants, the coefficient of variation was 0.38%-4.43%, and the method detection limits of the four TSILs were lower than 1.40 ng g^-1. These results meet the standards of residue analysis. The present study can provide an analysis method for studying TSIL residues and toxicity in the environment.

Determination and pharmacokinetics study of UK-5099 in mouse plasma by LC-MS/MS

BACKGROUND

UK-5099 is a potent mitochondrial acetone carrier inhibitor, that exhibits anticancer activity. Recently, the anti-Toxoplasma gondii activity of UK-5099 was proposed, and in vivo studies of its pharmacokinetics in BALB/c mice are necessary to further evaluate the clinical effect of UK-5099.

METHODS AND RESULTS

A simple and fast high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) analysis method was established and verified in terms of its linearity, matrix effect, accuracy, precision, recovery and stability. The analytes were separated by an Agilent ZORBAX XDB-C18 column (2.1 × 50 mm, 3.5 μm) at 30 °C. A gradient mobile phase consisting of water with 0.1% formic acid (FA) (phase A) and acetonitrile (ACN) (phase B) was delivered at a flow rate of 0.40 mL·min^-1 with an injection volume of 5 μL. A good linear response was obtained in a concentration range of 5-5000 ng·mL^-1 (r² = 0.9947). The lower limit of quantification (LLOQ) was 5 ng·mL^-1. The extraction recovery of UK-5099 was greater than 95%. The inter- and intra-day accuracy and precision of the method showed relative standard deviations (RSDs) of less than 15%. This method has been successfully applied to the pharmacokinetic evaluation of UK-5099 in mouse plasma. In health mice, the main pharmacokinetic parameters of UK-5099 after intraperitoneal administration were measured using a noncompartmental model, in which the AUC_0-t was 42,103 ± 12,072 ng·h·mL^-1 and the MRT_0-t was 0.857 ± 0.143 h. The peak concentration (C_max) was 82,500 ± 20,745 ng·h·mL^-1, which occurred at a peak time (T_max) = 0.250 ± 0.000 h.

CONCLUSIONS

A fast and sensitive HPLC-MS/MS method was developed, validated and successfully used for the determination of UK-5099 levels in mice after intraperitoneal administration. This study was the first report of the pharmacokinetic parameters of UK-5099 in mice, which will help to further study the administration of UK-5099 in animals and humans.

First Evidence of Glyphosate in American Horseshoe Crab from the Yucatan Peninsula in Mexico

Glyphosate is the most used herbicide in the world. Unfortunately, contamination of water bodies by this herbicide has been reported. A severe concern has been triggered given its detrimental impact on the environment and wildlife. The American horseshoe crab (Limulus polyphemus) is a benthic arthropod that inhabits the Yucatan Peninsula in Southeast Mexico. This study evaluates the glyphosate concentration in 34 recently dead specimens of L. polyphemus from four localities of the Ria Lagartos Biosphere Reserve in Yucatan, Mexico. The analysis was carried out using High-Performance Liquid Chromatography coupled with a Triple Quadrupole Mass Spectrometer. All the samples showed residues of glyphosate in the range from 0.08 to 2.38 ng g-1. These records constitute the first evidence of glyphosate bioaccumulation in this species. Although the scope might be limited, the results demonstrate a potentially prejudicial exposition of the marine biota to glyphosate-based herbicides, given its use in the region.

Method Development and Validation of Seven Pyrethroid Insecticides in Tea and Vegetable by Modified QuEChERS and HPLC-MS/MS

This study developed a quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure for determining seven pyrethroid pesticide residues in tea, cucumber, and tomato via high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The overall average recoveries of the seven pyrethroids were 72%-104% (relative standard deviation (RSD); 2.0%-16.1%, 89%-109% (RSD; 0.7%-17.3%), 82%-110% (RSD; 1.6%-17.1%) for tea, cucumber and tomato, respectively. The determination coefficient (R²), the limit of detection (LOD), and the limit of quantification (LOQ) were ≥ 0.99, 0.007-1.875 μg kg^-1, and 0.025-6.250 μg kg^-1, respectively. The method was successfully used to monitor the pyrethroid pesticide residues in market samples. HPLC-MS/MS rapidly, sensitively, and accurately determined the pyrethroid pesticide residues.

Screening and characterization of potential α-glucosidase inhibitors from Cercis chinensis Bunge fruits using ultrafiltration coupled with HPLC-ESI-MS/MS

A more accurate HPLC-MS screening method combining functional enzyme assay and affinity ultrafiltration screening assay was developed and applied for the screening of natural product inhibitors of α-glucosidase from Cercis chinensis Bunge fruits. The enzyme assay was conducted to prescreen botanical extracts, in which maltose was used as the substrate and detection object. That showed the Cercis chinensis Bunge fruits demonstrated higher α-glucosidase inhibitory activity (IC₅₀ = 11.94 ± 1.23 μg/mL) than acarbose (IC₅₀ = 44.03 ± 4.37 μg/mL) (n = 3, p < 0.05). Subsequently, twelve bioactive components targeting α-glucosidase were screened out and identified using affinity ultrafiltration coupled to liquid chromatography-mass spectrometry. The known inhibitor, acarbose, was used as a positive control and competitive ligand to eliminate false positives. Moreover, bindings of the twelve components to the active site of α-glucosidase were investigated via molecular docking, which further confirmed the results of the screening assay.

Development and Validation of Multi-Residue Method for Drugs Analysis in Human Feces by Liquid Chromatography-Tandem Mass Spectrometry

The use of veterinary drugs in animal production is a common practice to secure animal and human health. However, residues of administrated drugs could be present in animal food products. Levels of drugs in food of animal origin are regulated within the European Union. In recent years, residues have been detected not only in food, but also in the environmental elements such as water or soil, meaning that humans are involuntarily exposed to these substances. This article presents a multiclass method for the analysis of various therapeutic groups of pharmaceuticals in human feces. Pharmaceuticals are extracted from feces with an acid extraction solvent, and after filtration the extract was analyzed by HPLC-MS/MS. A limit of detection of 10 ng/g was achieved for 9 pharmaceuticals, with linearity over 0.99 and repeatability and reproducibility lower than 20%. The method was satisfactorily applied in 25 feces samples of individuals that had declared not to be under medical treatment for the last two months. Results indicate the presence of six different compounds at concentration between 10 and 456 ng/g. This preliminary study showed the involuntary exposure of human gut microbiota to active substances such as pharmaceuticals.

A survey of Methylobacterium species and strains reveals widespread production and varying profiles of cytokinin phytohormones

Background

Symbiotic Methylobacterium strains comprise a significant part of plant microbiomes. Their presence enhances plant productivity and stress resistance, prompting classification of these strains as plant growth-promoting bacteria (PGPB). Methylobacteria can synthesize unusually high levels of plant hormones, called cytokinins (CKs), including the most active form, trans-Zeatin (tZ).

Results

This study provides a comprehensive inventory of 46 representatives of Methylobacterium genus with respect to phytohormone production in vitro, including 16 CK forms, abscisic acid (ABA) and indole-3-acetic acid (IAA). High performance-liquid chromatography—tandem mass spectrometry (HPLC–MS/MS) analyses revealed varying abilities of Methylobacterium strains to secrete phytohormones that ranged from 5.09 to 191.47 pmol mL⁻¹ for total CKs, and 0.46 to 82.16 pmol mL⁻¹ for tZ. Results indicate that reduced methanol availability, the sole carbon source for bacteria in the medium, stimulates CK secretion by Methylobacterium. Additionally, select strains were able to transform L-tryptophan into IAA while no ABA production was detected.

Conclusions

To better understand features of CKs in plants, this study uncovers CK profiles of Methylobacterium that are instrumental in microbe selection for effective biofertilizer formulations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02454-9.

Magnetic Solid-Phase Extraction Based on Magnetic Sulfonated Reduced Graphene Oxide for HPLC-MS/MS Analysis of Illegal Basic Dyes in Foods

In this study, a magnetic solid-phase extraction (MSPE) method coupled with High-Performance Liquid Chromatography Mass Spectrometry (HPLC–MS/MS) for the determination of illegal basic dyes in food samples was developed and validated. This method was based on Magnetic sulfonated reduced graphene oxide (M-S-RGO), which was sensitive and selective to analytes with structure of multiaromatic rings and negatively charged ions. Several factors affecting MSPE efficiency such as pH and adsorption time were optimized. Under the optimum conditions, the calibration curves exhibited good linearity, ranging from 5 to 60 µg/g with correlation coefficients >0.9950. The limits of detection of 16 basic dyes were in the range of 0.01–0.2 µg/L. The recoveries ranged from 70% to 110% with RSD% < 10%. The results indicate that M-S-RGO is an efficient and selective adsorbent for the extraction and cleanup of basic dyes. Due to the MSPE procedures, matrix effect and interference were eliminated in the analysis of HPLC–MS/MS without the matrix-matched standards. Thus, validation data showed that the proposed MSPE–HPLC–MS/MS method was rapid, efficient, selective, and sensitive for the determination of illegal basic dyes in foods.

HPLC-MS/MS studies of brimonidine in rabbit aqueous humor by microdialysis

Aim: The pharmacokinetic study of the brimonidine tartrate in situ gel in the anterior chamber of the rabbit eye was studied by microdialysis technique, and samples were analyzed by HPLC-MS/MS. Materials & methods: It was monitored in ESI mode at transition 291.9→212.0 and 296.0→216.0 for brimonidine and internal standard, respectively. Acetonitrile and 0.1% aqueous formic acid (50:50, v/v) were used as the mobile phase at 0.4 ml/min. Results & conclusion: It showed a good linear correlation between 5 and 5000 ng/ml in microdialysis solution, and the inter- and intra-day precision (relative standard deviation) was less than 4.0%. The pharmacokinetic study showed that the AUC_(0-t) of in situ gel was 3.5-times than that of eyedrops, which significantly improve the bioavailability of brimonidine.

High Performance Liquid Chromatography-Tandem Mass Spectrometry Method for Correlating the Metabolic Changes of Lactate, Pyruvate and L-Glutamine with Induced Tamoxifen Resistant MCF-7 Cell Line Potential Molecular Changes

Breast cancer is one of the most prevalent cancers worldwide usually treated with Tamoxifen. Tamoxifen resistance development is the most challenging issue in an initially responsive breast tumor, and mechanisms of resistance are still under investigation. The objective of this study is to develop and validate a selective, sensitive, and simultaneous high performance liquid chromatography–tandem mass spectrometry method to explore the changes in substrates and metabolites in supernatant media of developed Tamoxifen resistance MCF-7 cells. We focus on the determination of lactate, pyruvate, and L-glutamine which enables the tracking of changes in metabolic pathways as a result of the resistance process. Chromatographic separation was achieved within 3.5 min. using a HILIC column (4.6 × 100 mm, 3.5 µm particle size) and mobile phase of 0.05 M acetic acid–ammonium acetate buffer solution pH 3.0: Acetonitrile (40:60 v/v). The linear range was 0.11–2.25, 0.012–0.227, and 0.02–0.20 mM for lactate, pyruvate, and L-glutamine, respectively. Within- and between-run accuracy was in the range 98.94-105.50% with precision (CV, %) of ≤0.86%. The results revealed a significant increase in both lactate and pyruvate production after acquiring the resistant. An increase in L-glutamine levels was also observed and could be attributed to its over production or decline in its consumption. Therefore, further tracking of genes responsible of lactate, pyruvate, and glutamine metabolic pathways should be performed in parallel to provide in-depth explanation of resistance mechanism.

μSPE followed by HPLC-MS/MS for the determination of series D and E resolvins in biological matrices

The critical role of acute inflammatory processes is recognized in many chronic diseases; a key point in molecular mechanisms of acute inflammation resolution is represented by a new group of pro-resolving lipid mediators that include distinct families of molecules: lipoxins, resolvins, protectins and maresins, collectively termed "specialized pro-resolving mediators" (SPMs). In particular, resolvins are active in the picogram to nanogram dose range, whereby they can directly modulate a plethora of anti-inflammatory responses. The presented method proposes an analytical protocol able to extract and to quantify 6 different resolvins from 3 different matrices (plasma, cells and exudates). The method, validated according to the EMA guideline for bioanalysis, exhibited good precision (1%-20%) and accuracy (2%-20%). In particular, the combination of two different sample preparation techniques, Liquid-Liquid Extraction (LLE) and micro-Solid Phase Extraction (μSPE), applied for the first on this class of molecules, used for the extraction and clean-up respectively, led to high enrichment factor (20 fold) and consequently a high sensitivity (LOQ between 1 and 38 pg mL^-1); moreover the validation data proved the versatility of μSPE as clean-up tool as it was capable to manage huge enrichment factor without negatively affect accuracy and precision of analysis.

Detection of Antimicrobial Residues in Poultry Litter: Monitoring a Risk through a Selective and Sensitive HPLC-MS/MS Method

Simple Summary

After administration of antimicrobials, poultry excrete significant concentrations of antimicrobials through their droppings, which accumulate in the litter where poultry are housed. Poultry litter, which consists mainly of wood shavings, feathers, and droppings, is widely used as an agricultural fertilizer worldwide. The period that antimicrobials persist in agricultural soils could present various environmental and public health concerns. Thus, in this research, a method to identify different families of antimicrobials in poultry litter was developed. Results show that HPLC–MS/MS can reliably detect nine different compounds from three families of antimicrobials. This method was used to identify antimicrobials from commercial poultry flocks, providing a valuable and specific tool to monitor these residues in poultry litter prior to its use as an agricultural fertilizer.

Abstract

Tetracyclines, sulphonamides, and quinolones are families of antimicrobials (AMs) widely used in the poultry industry and can excrete up to 90% of AMs administrated, which accumulate in poultry litter. Worryingly, poultry litter is widely used as an agriculture fertilizer, contributing to the spread AMs residues in the environment. The aim of this research was to develop a method that could simultaneously identify and quantify three AMs families in poultry litter by high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS). Samples of AMs free poultry litter were used to validate the method according to 657/2002/EC and VICH GL49. Results indicate that limit of detection (LOD) ranged from 8.95 to 20.86 μg kg⁻¹, while limits of quantitation (LOQ) values were between 26.85 and 62.58 µg kg⁻¹ of tetracycline, 4-epi-tetracycline, oxytetracycline, 4-epi-oxytetracycline, enrofloxacin, ciprofloxacin, flumequine, sulfachloropyridazine, and sulfadiazine. Recoveries obtained ranged from 93 to 108%. The analysis of field samples obtained from seven commercial poultry flocks confirmed the adequacy of the method since it detected means concentrations ranging from 20 to 10,364 μg kg⁻¹. This provides us an accurate and reliable tool to monitor AMs residues in poultry litter and control its use as agricultural fertilizer.

LC-MS/MS analysis and pharmacokinetics of daidzein and its 7-O-glucuronide in rats after oral administration of 7-O-L-valyl carbamate prodrug

Background: A valine carbamate prodrug (7-P) was designed to enhance the low bioavailability of daidzein due to its low water solubility and membrane permeability. Here, we developed a high-throughput HPLC-MS/MS method to measure daidzein and its 7-O-glucuronide after oral administration of daidzein or 7-P. Materials & methods: A HPLC-MS/MS method was validated and successfully applied to assess the pharmacokinetic behavior of daidzein and its 7-O-glucuronide after orally administrating daidzein or 7-P. The validated method on selectivity, linearity (r ≥ 0.995), precision (relative standard deviation <11.4%), accuracy (relative error <7.1%), extraction recovery (>92.4%), matrix effect (<8.2%) and stability were satisfied. Conclusion: The proposed economical, rapid and sensitive method will be an alternative analytical procedure for daidzein and its metabolite in biological samples.

Facile synthesis of covalent organic frameworks functionalized with graphene hydrogel for effectively extracting organophosphorus pesticides from vegetables

A novel covalent organic framework material (3DGA@COFs), for use as a solid-phase dispersion sorbent, has been synthesized for extracting organophosphorus pesticides (OPs) from vegetables. The prepared 3DGA@COFs material exhibited many advantageous features, including a large specific surface area (127.95 m²/g) and high pore volume (0.0344 cm³/g), which made it an ideal sorbent for sample pretreatment. The experimental conditions affecting extraction performance (adsorbent type, adsorbent amount, reaction time, pH, ionic concentration, and eluent) were optimized systematically. The extracted analytes were detected by HPLC-MS/MS. Under optimized conditions, the proposed method exhibited a wide linear range (0.5-100 μg/L) and low limits of detection (0.01-0.14 μg/L). The recoveries (75.40%-102.13%) satisfied the requirements for a precise detection method. The proposed method was successfully used for determining malathion, triazophos, quinalphos in lettuce, tomato and cucumber samples, thus indicating the potential of using 3DGA@COFs materials for pretreating vegetable samples.

Identifying and characterizing the components related to the brown color of Chinese sugar-smoked chicken during processing

The desired color is a key indicator for consumer acceptability of Chinese sugar-smoked chicken. To investigate the formation of color attributes of Chinese sugar-smoked chicken during processing, color values, structural characteristics, and components of brown pigment were evaluated in 2 groups, which were defined as brown skin (BS) and normal skin (NS) of Chinese sugar-smoked chicken based on their color values. Compared with the NS samples, the BS samples showed significantly lower values of lightness, redness, and yellowness and higher content of malondialdehyde and 5-hydroxymethylfurfural. UV-visible and Fourier-transform infrared spectra suggested that the structure of brown pigment was similar to melanin. The brown pigment consisted of multiple chemical components including the polymer of fructose and glucose, and derivatives produced by lipid oxidation, which were identified by HPLC-tandem mass spectrometry. The polymer content of glucose and fructose, which was demonstrated as sucrose by HPLC analysis, was higher in the BS group than in the NS group. Our results indicated that the higher content of the polymer of glucose and fructose was mainly responsible for the brown color of Chinese sugar-smoked chicken.

Tetrodotoxin and Its Analogues in Cephalothrix cf. simula (Nemertea: Palaeonemertea) from the Sea of Japan (Peter the Great Gulf): Intrabody Distribution and Secretions

Some nemertean species from the genus Cephalothrix accumulate tetrodotoxin (TTX) in extremely high concentrations. The current study is the first to provide high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) data on tetrodotoxin and its analogues (TTXs) profile and concentration in different regions and organs of Cephalothrix cf. simula, and its secretions produced in response to stimulation. Different specimens of C. cf. simula possessed 7-11 analogues, including nine previously found in this species and two new for nemerteans-4,9-anhydro-8-epi-5,6,11-trideoxyTTX and 1-hydroxy-8-epi-5,6,11-trideoxyTTX. The study of the toxins' distribution in different regions and organs of nemerteans revealed the same qualitative composition of TTXs throughout the body but differences in the total concentration of the toxins. The total concentration of TTXs was highest in the anterior region of the body and decreased towards the posterior; the ratio of the analogues also differed between regions. The data obtained suggest a pathway of TTXs uptake in C. cf. simula and the role of toxins in the life activity of nemerteans.

The level variation of Nε-(carboxymethyl)lysine is correlated with chlorogenic acids in Arabica L. Coffee beans under different process conditions

N^ε-(carboxymethyl) lysine (CML) is universally used as a marker of the occurrence of advanced glycation end products (AGEs) in foods. This study investigated the level changes of CML, chlorogenic acids (CQAs), lysine (Lys), fat and pH in coffee during roasting. The CML level went up slowly in the first 10 mins, then declined sharply during the next 2 mins, and kept increasing constantly in the following baking time, while the lowest CML level was obtained by roasting at 235 °C for 12 mins. The three CQAs isomers had different efficacy in affecting the levels of CML and other factors, indicating the CQAs isomers may play an important role in influencing the CML level. So it might be possible to regulate the formation of CML and gain better coffee quality via adjusting the levels of CQAs in baking process. This study provided important enlightenment on CML control during coffee baking.

Characterization of Andean Blueberry in Bioactive Compounds, Evaluation of Biological Properties, and In Vitro Bioaccessibility

The aim of this study was to evaluate Andean blueberries (Vaccinium floribundum Kunth) from Ecuador as a potential functional ingredient for the food and pharmaceutical industries. The analysis of bioactive compounds by HPLC–DAD–MSⁿ determined a high content of (poly)phenols, mainly anthocyanins, and the presence of the carotenoid lutein. Regarding its biological properties, Andean blueberry did not show toxicity by the zebrafish embryogenesis test, showing also a lack of the antinutrients lectins. Moreover, the results of in vitro and in vivo antioxidant capacity evaluation suggested its possibility to be used as natural antioxidant. This fruit also exhibited antimicrobial activity toward Staphylococcus aureus and Escherichia coli in low doses. Finally, in vitro gastrointestinal (GI) digestion showed a partial bioaccessibility of (poly) phenols (~50% at the final step), showing high antioxidant capacity in the different GI phases. These results revealed Andean blueberry as an interesting candidate for being used as a functional ingredient and the development of further in vivo and clinical assays.

Detection of toxic methylenecyclopropylglycine and hypoglycin A in litchi aril of three Chinese cultivars

As a subtropical fruit with high commercial values, litchi is also a source of methylenecyclcopropylglycine (MCPG) and hypoglycin A (HGA), which could cause hypoglycemia and fatal encephalopathy in human. In this work, a quantitative method was developed well to detect MCPG and HGA present in litchi aril of different cultivars. Method validation was evaluated well by linearity, recovery, precision and sensitivity. Among three cultivars, 'Feizixiao' contained the highest toxin level with 0.60-0.83 mg kg^-1 of MCPG and 10.66-14.46 mg kg^-1 of HGA, followed by 'Huaizhi' with 0.08-0.12 mg kg^-1 of MCPG and 0.63-1.54 mg kg^-1 of HGA, and 'Nuomici' with 0.09-0.11 mg kg^-1 of MCPG and 0.35-0.91 mg kg^-1 of HGA. The toxin levels were highly associated with litchi cultivar and storage time. These findings can provide new knowledge to help to recommend the safe consumption of fresh litchi based on human health.

Facile synthesis of magnetic sulfonated covalent organic framework composites for simultaneous dispersive solid-phase extraction and determination of β-agonists and fluoroquinolones in food samples

In this work, an efficient method for the determination of β-agonists and fluoroquinolones was established, based on a mixed-mode sorbent of magnetic sulfonated covalent organic framework composites. By coupling with HPLC-MS/MS, the main factors that affect the extraction procedure were optimized. Under the optimal conditions, the proposed HPLC-MS/MS method was successfully utilized for the extraction of β-agonists and fluoroquinolones in milk and pork meat samples. The method showed good linearities (R² ≥ 0.9916), and low LOQs of 0.1-0.2 ng g^-1 for β-agonists and fluoroquinolones. The adsorption mechanism was investigated with the assistance of quantum chemistry calculation method, and it is worth noting that the sorbent relied mainly on the multiple adsorption mechanisms, including π-π stacking, hydrophobic, electrostatic attraction and hydrogen-bonding interactions. This work not only provides a simple method for the preparation of a mixed-mode sorbent, but also a routine analysis strategy for monitoring the illegal use of β-agonists and fluoroquinolones.

Comparative Analysis of Far East Sikhotinsky Rhododendron (Rh. sichotense) and East Siberian Rhododendron (Rh. adamsii) Using Supercritical CO2-Extraction and HPLC-ESI-MS/MS Spectrometry

Rhododendron sichotense Pojark. and Rhododendron adamsii Rheder have been actively used in ethnomedicine in Mongolia, China and Buryatia (Russia) for centuries, as an antioxidant, immunomodulating, anti-inflammatory, vitality-restoring agent. These plants contain various phenolic compounds and fatty acids with valuable biological activity. Among green and selective extraction methods, supercritical carbon dioxide (SC-CO₂) extraction has been shown to be the method of choice for the recovery of these naturally occurring compounds. Operative parameters and working conditions have been optimized by experimenting with different pressures (300–400 bar), temperatures (50–60 °C) and CO₂ flow rates (50 mL/min) with 1% ethanol as co-solvent. The extraction time varied from 60 to 70 min. A HPLC-UV-VIS-ESI-MS/MS technique was applied to detect target analytes. A total of 48 different biologically active components have been identified in the Rh. adamsii SC-CO₂ extracts. A total of 31 different biologically active components have been identified in the Rh. sichotense SC-CO₂ extracts.

Characteristics of Korean patients with methamphetamine use disorder based on the quantitative analysis of methamphetamine and amphetamine in hair

Methamphetamine (MA) is a highly addictive central nervous system stimulant. MA use disorder is characterized by a chronic, relapsing brain disease that is enhanced by a dynamic process of repeated use and withdrawal. The analysis of MA and its metabolite, amphetamine (AM), in hair is routinely performed in forensic laboratories for illegal MA use determination. However, few studies regarding the clinical application of hair analysis have been conducted to monitor the treatment of MA use disorder. Herein, the characteristics of Korean patients with MA use disorder were investigated based on drug abuse screening instruments and quantitative analysis of MA and AM in hair. A HPLC-MS/MS method for the quantification of MA and AM in hair was validated and clinically applied to healthy subjects (HS, n = 30, male) as well as current (CP, n = 33, male) and former (FP, n = 22, male) MA use disorder patients. The validation results of the hair analysis method showed high selectivity, accuracy, and precision with acceptable linearity within the calibration range (0.05-5.0 ng/mg). The limit of detection (LOD) and limit of quantification for both MA and AM were 0.05 ng/mg. The concentrations of MA and AM ranged from ≤ LOD to 166 ng/mg and from not detected (ND) to 9.15 ng/mg in the CP group and from ND to 6.14 ng/mg and from ND to 0.32 ng/mg in the FP group, respectively. No correlation was observed between the hair MA concentrations and the NIDA-modified ASSIST, DUDID extended, or DAST scores in both groups. The hair MA concentrations showed advantages for differentiating the CP and FP groups compared with the scores provided by the above-mentioned drug abuse screening instruments.

HPLC-MS/MS method for the determination and pharmacokinetic study of six compounds against rheumatoid arthritis in rat plasma after oral administration of the extract of Caulophyllum robustum Maxim

Caulophyllum robustum Maxim (CRM) is a well-known traditional Chinese medicine (TCM) mainly present in the northeast, northwest and southwest regions of China, which is belong to the family Berberidaceae. The roots and rhizomes of CRM have been used as a famous TCM for the treatment of rheumatoid arthritis (RA). The selective, sensitive and accurate high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) method for the determination and pharmacokinetic study cauloside H, leonticin D, cauloside G, cauloside D, cauloside C and magnoflorine in rat plasma was developed and validated in this paper. Chromatographic separation was achieved by using a Waters ACQUITY UPLC HSS T3 (100 mm × 2.1 mm, 1.7 μm) with gradient elution using a mobile phase consisting of acetonitrile and 0.1 % formic acid in water at a flow rate of 0.4 mL/min. The detection was performed in multiple reaction monitoring (MRM) mode and electrospray ionization (ESI) in positive and negative modes. The linearity, precision, accuracy, extraction recovery, matrix effects and stability were assessed to validate the current high-performance liquid chromatography/mass spectrometry (HPLC-MS) assay. Good linearity was achieved for each analyte with a correlation coefficient (r²) > 0.99). All the precision (RSD) data were less than 12.20 %, the accuracies ranged from -12.39 % to 10.55 %, the recovery rates from the rat plasma ranged from 85.48%-98.69 %, and the matrix effects ranged from 80.96 % to 91.35 %. The validated approach was successfully applied to study the pharmacokinetic characteristics of saponins and alkaloids in plasma after administering CRME to rats, and this assay provides a platform for studying the active components of multicomponent traditional Chinese medicines and provides useful information for further clinical studies.

Determination of KD025 (SLx-2119), a Selective ROCK2 Inhibitor, in Rat Plasma by High-Performance Liquid Chromatography-Tandem Mass Spectrometry and its Pharmacokinetic Application

KD025 (SLx-2119), the first specific Rho-associated protein kinase 2 (ROCK2) inhibitor, is a potential new drug candidate currently undergoing several phase 2 clinical trials for psoriasis, idiopathic pulmonary fibrosis, chronic graft-versus-host disease, and systemic sclerosis. In this study, a bio-analytical method was developed and fully validated for the quantification of KD025 in rat plasma and for application in pharmacokinetic studies. KD025 and GSK429286A (the internal standard) in rat plasma samples were analyzed by high-performance liquid chromatography-tandem mass spectrometry with m/z transition values of 453.10 → 366.10 and 433.00 → 178.00, respectively. The method was fully validated according to the United State Food and Drug Administration guidelines in terms of selectivity, linearity, accuracy, precision, sensitivity, matrix effects, extraction recovery, and stability. The method enabled the quantification of KD025 levels in rat plasma following oral administration of 5 mg/kg KD025 and intravenous administration of 2 mg/kg KD025 to rats, respectively. Our findings suggest that the developed method is practical and reliable for pharmacokinetic studies of KD025 in preclinical animals.

Determination of Eight Coccidiostats in Eggs by Liquid-Liquid Extraction-Solid-Phase Extraction and Liquid Chromatography-Tandem Mass Spectrometry

A method for the simultaneous determination of robenidine, halofuginone, lasalocid, monensin, nigericin, salinomycin, narasin, and maduramicin residues in eggs by liquid chromatography–tandem mass spectrometry (LC–MS/MS) was developed. The sample preparation method used a combination of liquid–liquid extraction (LLE) and solid-phase extraction (SPE) technology to extract and purify these target compounds from eggs. The target compounds were separated by gradient elution using high-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography (UPLC). Tandem mass spectrometry was used to quantitatively and qualitatively analyze the target compounds via electrospray ionization (ESI⁺) and multiple reaction monitoring mode. The HPLC–MS/MS and UPLC–MS/MS methods were validated according to the requirements defined by the European Union and the Food and Drug Administration. The limits of detection and limits of quantification of the eight coccidiostats in eggs were 0.23–0.52 µg/kg and 0.82–1.73 µg/kg for HPLC–MS/MS, and 0.16-0.42 µg/kg and 0.81-1.25 µg/kg for UPLC–MS/MS, respectively. The eggs were spiked with four concentrations of the eight coccidiostats, and the HPLC–MS/MS and UPLC–MS/MS average recoveries were all higher than 71.69% and 72.26%, respectively. Compared with the HPLC–MS/MS method, utilizing UPLC–MS/MS had the advantages of low reagent consumption, a short detection time, and high recovery and precision. Finally, the HPLC–MS/MS and UPLC–MS/MS methods were successfully applied to detect eight coccidiostats in 40 eggs.

N-Nitrosamine formation from chloramination of two common ionic liquids

Ionic liquids (ILs) are a class of solvents increasingly used as "green chemicals." Widespread applications of ILs have led to concerns about their accidental entry to the environment. ILs have been assessed for some environmental impacts; however, little has been done to characterize their potential impacts on drinking water if ILs accidentally enter surface water. IL cations are often aromatic or alkyl quaternary amines that resemble structures of previously confirmed N-nitrosamine (NA) precursors. Therefore, this study has evaluated two common ILs, 1-ethyl-3-methylimidazolium bromide (EMImBr) and 1-ethyl-1-methylpyrrolidinium bromide (EMPyrBr), for their NA formation potential. Each IL species was reacted with pre-formed monochloramine under various laboratory conditions. The reaction mixtures were extracted using liquid-liquid extraction and analyzed for NAs using high performance liquid chromatography tandem mass spectrometry. At low concentration of IL (250 μmol/L), the yields of NAs (NMEA or NPyr) increased with increasing doses of monochloramine from both IL species. The total NA yield was as high as 2.5 ± 0.3 ng/mg from EMImBr, and as high as 8.6 ± 0.8 ng/mg from EMPyrBr. At high concentration of IL (5 mmol/L), the NA yield reached a maximum at 2.5 mmol/L NH₂Cl, and then decreased with subsequent increases in the reactant concentrations, demonstrating ILs' solvent effects. This study re-emphasizes the importance of preventing discharge of ILs to water bodies to prevent secondary impacts on drinking water.