Fast extraction and dilution flow injection mass spectrometry method for quantitative chemical residue screening in food

Method validation, residue behaviour and dietary risk assessment of insecticides (cyantraniliprole, acetamiprid, flubendiamide and its metabolite, des-iodo flubendiamide) in or on broccoli using LC-MS/MS

Residue behaviour and dietary risk assessment of cyantraniliprole, flubendiamide and acetamiprid in broccoli were carried out using the QuEChERS (quick, easy, cheap, effective, rugged and safe) technique coupled with LC-MS/MS. The QuEChERS technique was validated on parameters such as linearity, accuracy, precision, robustness, matrix effects, limit of quantification (LOQ), specificity, retention time and ion ratio as per SANTE (Directorate General for Health and Food Safety) guidelines to attest to the specificity, accuracy and precision of the analytical method in estimating insecticide residues in and on broccoli heads and cropped soil. The LOQ of the method for all three insecticides was 0.01 mg/kg. The initial deposits of cyantraniliprole, flubendiamide and acetamiprid reduced to half of its concentration in 1.873-2.354, 1.975-2.484 and 1.371-1.620 days, respectively. No residues were detected in broccoli-cropped soil at harvest time (30 days after last spray). The proposed maximum residue limits (MRLs) of 1.5, 0.5-0.9 and 2.0-3 mg/kg for cyantraniliprole, flubendiamide and acetamiprid were calculated using the Organisation for Economic Co-operation and Development MRL calculator. The acute and chronic dietary risk assessment of the tested insecticides identified no appreciable dietary risk to the Indian population from the consumption of broccoli heads. The findings of no dietary risk highlight the importance of informed pesticide usage in broccoli and the proposed MRL derived from this study offers crucial guidelines for the regulatory authorities, ensuring the safety of broccoli consumption.

Flow-injection MS analysis as a simplified approach to pesticide screening in apples

A fast and simplified method based on mass spectrometry analysis was developed for pesticide qualification in apple peel. The main feature of the method is flow-injection of the loop pre-defined sample volume directly to the MS source, with no chromatographic separation. Method performances were evaluated for five pesticides regularly used in apple orchard treatments. First, primary features of the method such as the loop injection dynamics, total analysis time, chronogramic peaks integrity and sensitivity were evaluated. Then the applicability of the method for qualitative and quantitative screening was assessed on citrate buffered QuEChERS cleaned-up apple peel samples. The developed method offers a possibility for simplified, more economic high throughput screening for pesticides in apples. The method is intended to be a tool for preliminary qualitative assessment of pesticides residues in fruit. Quantitative features of the method are analyte and sample preparation dependent, most certainly due to the lack of chromatography.

Safety Assessment of Locusta migratoria Powder Enriched Peanut-Based Ready-to-Use Therapeutic Foods (RUTF)

Migratory locust has been widely reported as a quality protein source. However, there are food safety problems related with the usage of insects as food. In this study, migratory locust powder (MLP) was used as a protein supply alternative to milk powder (MP) in peanut-based RUTFs. Seven formulations were obtained at different substitution levels (0 – 30%) of MP with MLP. Pesticide residues, aflatoxins, triazine and toxic metals were analysed using a GC-MS system and Atomic Absorption Spectrophotometer. Formulation with 30% MLP and without milk have the highest level of organochlorine (3.22 µg/kg), organophosphorus (0.40-4.56µg/kg) amongst others. Aflatoxins of the therapeutic foods increased with increasing levels of MLP. The heavy metals, melamine, and cyanuric acid of the RUTFs were below the standard permissible limits. Migratory locust powder could be used as an alternate protein source in the formulation of peanut based RUTFs without posing health threat.

Uptake, translocation and distribution of cyantraniliprole in rice planting system

While cyantraniliprole has been frequently used in rice fields, knowledge of the uptake, translocation and distribution of cyantraniliprole in rice planting systems is still largely unexplored. Plant uptake is a crucial factor in determining how cyantraniliprole moves through the food chain. Understanding the uptake, translocation and distribution of cyantraniliprole in rice planting system is essential to predicting its accumulation in rice and potential human exposure. Herein, the uptake process of cyantraniliprole in a hydroponic-rice system was systematically investigated. Results showed that cyantraniliprole was easily absorbed by rice roots via a passive diffusion process through the apoplastic pathway and then translocated upward through the xylem, but its acropetal translocation was limited. Cyantraniliprole in shoots can also be downward translocated through the phloem, although only to a limited extent, showing rice plants' weak phloem movement capacity. Furthermore, cyantraniliprole had a short half-life in sediment-water system and dissipated faster in anaerobic than aerobic conditions. At the equilibrium stage of a sediment-water system, cyantraniliprole is preferentially partitioned to the solid phase. Our study provides a systematic insight into the uptake, translocation and distribution of cyantraniliprole in the rice planting system, which is very helpful for better field cyantraniliprole application and environmental risk assessment.

Design and synthesis of VEGFR-2 inhibitors based on oleanolic acid moiety

In this study, twenty-four oleanolic acid (OA) derivatives were rationally designed based on molecule docking studies and their VEGFR-2 inhibitory activities were tested by Homogeneous time-resolved fluorescence (HTRF) method in vitro. All of the synthesized compounds were identified as new compounds, and the structures of these compounds were determined by ¹H-NMR and ESI-MS. In the screening for VEGFR-2 inhibitors, compounds I₆ and I₇ exhibited excellent inhibitory effect. The results indicated that insertion of phenylurea group with a linker at position C-28 of OA can increase the activity against VEGFR-2 significantly. [Formula: see text].

Rapid identification of organophosphorus pesticides on contaminated skin and confirmation of adequate decontamination by ambient mass spectrometry in emergency settings

RATIONALE

Dermal exposure to pesticides may cause severe intoxication and even result in a fatal outcome. To expedite rescue in the emergency department, it is mandatory to develop a point-of-care analytical method for immediate identification of pesticides on the skin of exposed personnel, and to perform immediate dermal decontamination to prevent further harm and optimize the chance for full clinical recovery.

METHODS

Four of the most commonly used highly toxic pesticides that contaminate the skin were rapidly characterized by thermal desorption electrospray ionization mass spectrometry. The technique was also applied to confirm the completeness of pesticide decontamination from the skin. Pesticide sampling, desorption, ionization, and detection altogether took less than 30 s. In addition, different fabrics of protective garments worn by farmers were assessed with this efficient ambient mass spectrometric technique for their protective capabilities against dermal exposure to pesticides, and scanning electron microscopy was used to observe their different microstructures. The decontaminating efficacies of different cleansing agents for these skin contaminants were also evaluated by this technical platform.

RESULTS

The repeatability of this method had a low relative standard deviation (<22%) for the detection of pesticides on the surface of swine skin. The detection limits of the pesticides in solution were found to be in the range of 3-20 ng/mL. Linearity was observed between the signal intensities and the concentrations of the four pesticides in solution within the range of 50 ng/mL to 50 μg/mL (R² between 0.9921 and 0.9966). In addition, it was found that PVC fabric is optimal in preventing skin contamination by fenthion and detergent had the best efficiency for fenthion decontamination.

CONCLUSIONS

Since the whole analytical process is extremely fast, this technique allows early point-of-care identification of contaminating pesticides on the skin of exposed patients in the emergency room, as well as rapid assessment of the adequacy of decontamination.

Direct automatic determination of the methanol content in red wines based on the temperature effect of the KMnO4/K2S2O5/fuchsin sodium sulfite reaction system

The standard method for methanol assay in wine is based on a methanol/KMnO4/H2C2O4/fuchsin sodium sulfite (FSS) reaction system. However, it is difficult to control the degree of colour and the temperature of the reaction product in this assay, and its repeatability is also poor due to the generation of CO and CO2 in the reaction. Therefore, to solve these problems, potassium metabisulfite was selected to replace H2C2O4, and an automatic analysis method was developed which can realize rapid and accurate determination of methanol and can be used to make an online analyzer. It was discovered that the reactions of methanol/KMnO4 and acetaldehyde/FSS are exothermic, while the reactions of methanol/KMnO4 and formaldehyde/FSS are endothermic. Consequently, based on the temperature effect, not only was the interference of ethanol eliminated in detecting methanol in wines, the purpose of the research was achieved to directly and accurately determine methanol without sample pretreatment. By optimizing the system, the obtained conditions for determining methanol in wines were as follows: 20 g L-1 concentration for KMnO4; 3 g L-1 concentration for FSS; 40 cm length for the first reaction coil (RC1); 100 cm length for RC2; 700 cm (I.D.: 0.8 mm) length for RC3; 50 °C for RC3; about 20 °C for RC1 and RC2; 330 μL for the sample volume. The method showed a linear response in the range 25-1000 mg L-1, with a 0.6% RSD, 8.8 mg L-1 detection limit and 25 samples per h, and was successfully used for testing representative wine samples. It also obtained better accuracy than previous methods. Due to its superiority in automated operation, reproducibility, analysis speed and test cost, this method and system can serve as a supplementary standard for methanol assay, and for the quality control of the winemaking process and the final wine-product, as well as for low-alcohol drinks.

Advantages and Pitfalls of Mass Spectrometry Based Metabolome Profiling in Systems Biology

Mass spectrometry-based metabolome profiling became the method of choice in systems biology approaches and aims to enhance biological understanding of complex biological systems. Genomics, transcriptomics, and proteomics are well established technologies and are commonly used by many scientists. In comparison, metabolomics is an emerging field and has not reached such high-throughput, routine and coverage than other omics technologies. Nevertheless, substantial improvements were achieved during the last years. Integrated data derived from multi-omics approaches will provide a deeper understanding of entire biological systems. Metabolome profiling is mainly hampered by its diversity, variation of metabolite concentration by several orders of magnitude and biological data interpretation. Thus, multiple approaches are required to cover most of the metabolites. No software tool is capable of comprehensively translating all the data into a biologically meaningful context yet. In this review, we discuss the advantages of metabolome profiling and main obstacles limiting progress in systems biology.

Rapid identification of pesticides in human oral fluid for emergency management by thermal desorption electrospray ionization/mass spectrometry

Self-poisoning with pesticides accounts for approximately one-third of all suicides worldwide. To expedite rescue in the emergency department, it is essential to develop a point-of-care analytical method for rapid identification of ingested pesticides. In this study, five of the most common pesticides ingested by self-poisoning patients in Taiwan were analyzed from oral fluid samples. Pesticide-oral fluid mixtures were applied on a cotton swab and then transferred into methanol. A metallic probe was used to sample the methanol solution for subsequent thermal desorption-electrospray ionization mass spectrometry analysis. Altogether, pesticide sampling, transfer, desorption, ionization, and detection took less than 1 min. The reproducibility of this method (n = 6) was shown in the observed low-relative standard deviation (<7%) in the detection of pesticide in oral fluid. The detection limits of the pesticides in oral fluid obtained from four human subjects by thermal desorption-electrospray ionization mass spectrometry were between 1-10 ppb with relative standard deviation 10.7%. Moreover, in this study, linear responses of five pesticides in oral fluid with concentrations between 1 ppb-1 ppm (R2 between 0.9938 and 0.9988) were observed. As the whole analytical process is extremely short, this technique allows for early non-invasive point-of-care identification of pesticides in the oral fluid of self-poisoning patients in the emergency room, providing important toxicological information for decision-making during critical resuscitation.

Emerging flow injection mass spectrometry methods for high-throughput quantitative analysis

Where does flow injection analysis mass spectrometry (FIA-MS) stand relative to ambient mass spectrometry (MS) and chromatography-MS? Improvements in FIA-MS methods have resulted in fast-expanding uses of this technique. Key advantages of FIA-MS over chromatography-MS are fast analysis (typical run time <60 s) and method simplicity, and FIA-MS offers high-throughput without compromising sensitivity, precision and accuracy as much as ambient MS techniques. Consequently, FIA-MS is increasingly becoming recognized as a suitable technique for applications where quantitative screening of chemicals needs to be performed rapidly and reliably. The FIA-MS methods discussed herein have demonstrated quantitation of diverse analytes, including pharmaceuticals, pesticides, environmental contaminants, and endogenous compounds, at levels ranging from parts-per-billion (ppb) to parts-per-million (ppm) in very complex matrices (such as blood, urine, and a variety of foods of plant and animal origin), allowing successful applications of the technique in clinical diagnostics, metabolomics, environmental sciences, toxicology, and detection of adulterated/counterfeited goods. The recent boom in applications of FIA-MS for high-throughput quantitative analysis has been driven in part by (1) the continuous improvements in sensitivity and selectivity of MS instrumentation, (2) the introduction of novel sample preparation procedures compatible with standalone mass spectrometric analysis such as salting out assisted liquid-liquid extraction (SALLE) with volatile solutes and NH4(+) QuEChERS, and (3) the need to improve efficiency of laboratories to satisfy increasing analytical demand while lowering operational cost. The advantages and drawbacks of quantitative analysis by FIA-MS are discussed in comparison to chromatography-MS and ambient MS (e.g., DESI, LAESI, DART). Generally, FIA-MS sits 'in the middle' between ambient MS and chromatography-MS, offering a balance between analytical capability and sample analysis throughput suitable for broad applications in life sciences, agricultural chemistry, consumer safety, and beyond.

Electron ionization LC-MS with supersonic molecular beams--the new concept, benefits and applications

A new type of electron ionization LC-MS with supersonic molecular beams (EI-LC-MS with SMB) is described. This system and its operational methods are based on pneumatic spray formation of the LC liquid flow in a heated spray vaporization chamber, full sample thermal vaporization and subsequent electron ionization of vibrationally cold molecules in supersonic molecular beams. The vaporized sample compounds are transferred into a supersonic nozzle via a flow restrictor capillary. Consequently, while the pneumatic spray is formed and vaporized at above atmospheric pressure the supersonic nozzle backing pressure is about 0.15 Bar for the formation of supersonic molecular beams with vibrationally cold sample molecules without cluster formation with the solvent vapor. The sample compounds are ionized in a fly-though EI ion source as vibrationally cold molecules in the SMB, resulting in 'Cold EI' (EI of vibrationally cold molecules) mass spectra that exhibit the standard EI fragments combined with enhanced molecular ions. We evaluated the EI-LC-MS with SMB system and demonstrated its effectiveness in NIST library sample identification which is complemented with the availability of enhanced molecular ions. The EI-LC-MS with SMB system is characterized by linear response of five orders of magnitude and uniform compound independent response including for non-polar compounds. This feature improves sample quantitation that can be approximated without compound specific calibration. Cold EI, like EI, is free from ion suppression and/or enhancement effects (that plague ESI and/or APCI) which facilitate faster LC separation because full separation is not essential. The absence of ion suppression effects enables the exploration of fast flow injection MS-MS as an alternative to lengthy LC-MS analysis. These features are demonstrated in a few examples, and the analysis of the main ingredients of Cannabis on a few Cannabis flower extracts is demonstrated. Finally, the advantages of EI-LC-MS with SMB are listed and discussed.

Use of ammonium formate in QuEChERS for high-throughput analysis of pesticides in food by fast, low-pressure gas chromatography and liquid chromatography tandem mass spectrometry

The "quick, easy, cheap, effective, rugged, and safe" (QuEChERS) approach to sample preparation is widely applied in pesticide residue analysis, but the use of magnesium sulfate and other nonvolatile compounds for salting out in the method is not ideal for mass spectrometry. In this study, we developed and evaluated three new different versions of the QuEChERS method using more volatile salts (ammonium chloride and ammonium formate and acetate buffers) to induce phase separation and extraction of 43 representative pesticide analytes of different classes. Fast low-pressure gas chromatography tandem mass spectrometry (LPGC-MS/MS) and liquid chromatography (LC)-MS/MS were used for analysis. The QuEChERS AOAC Official Method 2007.01 was also tested for comparison purposes. Of the studied methods, formate buffering using 7.5g of ammonium formate and 15mL of 5% (v/v) formic acid in acetonitrile for the extraction of 15g of sample (5g for wheat grain) provided the best performance and practical considerations. Method validation was carried out with and without the use of dispersive solid-phase extraction for cleanup, and no significant differences were observed for the majority of pesticides. The method was demonstrated in quantitative analysis for GC- and LC-amenable pesticides in 4 representative food matrices (apple, lemon, lettuce, and wheat grain). With the typical exceptions of certain pH-dependent and labile pesticides, 90-110% recoveries and <10% RSD were obtained. Detection limits were mostly <5ng/g, which met the general need to determine pesticide concentrations as low as 10ng/g for monitoring purposes in food applications.

Residues of cyantraniliprole and its metabolite J9Z38 in rice field ecosystem

A simple and reliable analytical method was developed to detect cyantraniliprole (HGW86) and its metabolite J9Z38 in rice straw, paddy water, brown rice, and paddy soil. The fate of cyantraniliprole and its metabolite J9Z38 in rice field ecosystem was also studied. The target compounds were extracted using acetonitrile, cleaned up on silicagel or strong anion exchange column, and analyzed by ultra-performance liquid chromatography-tandem mass spectrometry. The average recoveries of cyantraniliprole and J9Z38 in rice straw, paddy water, brown rice, and paddy soil ranged from 79.0% to 108.6%, with relative standard deviations of 1.1-10.6%. The limits of quantification of cyantraniliprole and J9Z38 were 18 and 39μgkg(-1) for rice straw, 2.8 and 5.0μgkg(-1) for paddy water, 4.3 and 6.3μgkg(-1) for brown rice, and 3.9 and 5.3μgkg(-1) for paddy soil. The trial results showed that the half-lives of cyantraniliprole were 3.2, 4.4, and 6.3d in rice straw and 4.9, 2.0, and 6.2d in paddy water in Zhejiang, Hunan, and Shandong, respectively. The respective final residues of cyantraniliprole and J9Z38 in brown rice were lower than 0.05 and 0.02mgkg(-1) after 14d of pre-harvest interval. The maximum residue limit of cyantraniliprole at 0.1mgkg(-1) and dosage of 100g a.i.hm(-2), which could be considered safe to human beings and animals, were recommended.

Current metabolomics: technological advances

Metabolomics, the global quantitative assessment of metabolites in a biological system, has played a pivotal role in various fields of science in the post-genomic era. Metabolites are the result of the interaction of the system's genome with its environment and are not merely the end product of gene expression, but also form part of the regulatory system in an integrated manner. Therefore, metabolomics is often considered a powerful tool to provide an instantaneous snapshot of the physiology of a cell. The power of metabolomics lies on the acquisition of analytical data in which metabolites in a cellular system are quantified, and the extraction of the most meaningful elements of the data by using various data analysis tool. In this review, we discuss the latest development of analytical techniques and data analyses methods in metabolomics study.

Determination of 2-methylimidazole and 4-methylimidazole in caramel colors by capillary electrophoresis

The use of chemical preservative compounds is common in the food products industry. Caramel color is the most usual additive used in beverages, desserts, and breads worldwide. During its fabrication process, 2- and 4-methylimidazole (MeI), highly carcinogenic compounds, are generated. In these cases, the development of reliable analytical methods for the monitoring of undesirable compounds is necessary. The primary procedure for the analysis of 2- and 4-MeI is using LC- or GC-MS techniques. These procedures are time-consuming and require large amounts of organic solvents and several pretreatment steps. This prevents the routine use of this procedure. This paper describes a rapid, efficient, and simple method using capillary electrophoresis (CE) for the separation and determination of 2- and 4-MeI in caramel colors. The analyses were performed using a 75 μm i.d. uncoated fused-silica capillary with an effective length of 40 cm and a running electrolyte consisting of 160 mmol L(-1) phosphate plus 30% acetonitrile. The pH was adjusted to 2.5 with triethylamine. The analytes were separated within 6 min at a voltage of 20 kV. Method validation revealed good repeatability of both migration time (<0.8% RSD) and peak area (<2% RSD). Analytical curves for 2- and 4-MeI were linear in the 0.4-40 mg L(-1) concentration interval. Detection limits were 0.16 mg L(-1) for 4-MeI and 0.22 mg L(-1) for 2-MeI. The extraction recoveries were satisfactory. The developed method showed many advantages when compared to the previously used method.

Determination of cyantraniliprole and its major metabolite residues in pakchoi and soil using ultra-performance liquid chromatography-tandem mass spectrometry

A rapid, simple and reliable analytical method was developed for the determination of cyantraniliprole and its major metabolite J9Z38 in pakchoi and soil by using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The sample preparation approach is known as QuEChERS, which stands for quick, easy, cheap, effective, rugged and safe. Samples were extracted with acetonitrile, and cleaned up with dispersive primary and secondary amine sorbent before analysis by UPLC-MS/MS. The limit of quantitation for cyantraniliprole and J9Z38 was 0.01 mg/kg in both pakchoi and soil. Average recoveries of cyantraniliprole and J9Z38 at three fortified levels (0.01, 0.05, 0.1 mg/kg) ranged from 77.8% to 102.5% with relative standard deviation of 1.6%-8.9%. This method has been applied to the analysis of cyantraniliprole and J9Z38 residues in real pakchoi and soil samples selected from field. The results of the residue dynamic experiment showed that the half-life of cyantraniliprole ranged from 2.9 to 6.4 days in pakchoi and 8.7 to 18.2 days in soil, respectively. The final residual levels of cyantraniliprole in pakchoi and soil from Guangdong and Shanghai were below 0.20 and 0.10 mg/kg, respectively; similarly, the final residual levels of J9Z38 in pakchoi and soil from Guangdong and Shanghai were <0.07 and 0.01 mg/kg. These results will be helpful in setting maximum residue limit guidance for cyantraniliprole in pakchoi in China.

A flow-injection mass spectrometry fingerprinting scaffold for feature selection and quantitation of Cordyceps and Ganoderma extracts in beverage: a predictive artificial neural network modelling strategy

Flow-injection mass spectrometry (FI/MS) represents a powerful analytical tool for the quality assessment of herbal formula in dietary supplements. In this study, we described a scaffold (proof-of-concept) adapted from spectroscopy to quantify Cordyceps sinensis and Ganoderma lucidum in a popular Cordyceps sinensis /Ganoderma lucidum -enriched health beverage by utilizing flow-injection/mass spectrometry/artificial neural network (FI/MS/ANN) model fingerprinting method with feature selection capability. Equal proportion of 0.1% formic acid and methanol (v/v) were used to convert extracts of Cordyceps sinensis and Ganoderma lucidum into their respective ions under positive MS polarity condition. No chromatographic separation was performed. The principal m/z values of Cordyceps sinensis and Ganoderma lucidum were identified as: 104.2, 116.2, 120.2, 175.2, 236.3, 248.3, 266.3, 366.6 and 498.6; 439.7, 469.7, 511.7, 551.6, 623.6, 637.7 and 653.6, respectively. ANN models representing Cordyceps sinensis and Ganoderma lucidum were individually trained and validated using three independent sets of matrix-free and matrix-matched calibration curves at concentration levels of 2, 20, 50, 100, 200 and 400 μg mL^-1. Five repeat analyses provided a total of 180 spectra for herbal extracts of Cordyceps sinensis and Ganoderma lucidum. Root-mean-square-deviation (RMSE) were highly satisfactory at <4% for both training and validation models. Correlation coefficient (r²) values of between 0.9994 and 0.9997 were reported. Matrix blanks comprised of complex mixture of Lingzhi fermentation solution and collagen. Recovery assessment was performed over two days using six sets of matrix blank (n = 6) spiked at three concentration levels of approximately 83, 166 and 333 mg kg^-1. Extraction using acetonitrile provided good overall recovery range of 92-118%. A quantitation limit of 0.2 mg L^-1 was reported for both Cordyceps sinensis and Ganoderma lucidum. Intra-day and inter-day RMSE values of 7% or better were achieved. Application of the scaffold in a high-throughput routine environment would imply a significant reduction in effort and time, since the option of having a model driven analytical solution is now available.