A generic and rapid strategy for determining trace multiresidues of sulfonamides in aquatic products by using an improved QuEChERS method and liquid chromatography–electrospray quadrupole tandem mass spectrometry

Rapid determination and risk evaluation of multi-class antibiotics in aquatic products by one-step purification process coupled with ultra-high performance liquid chromatography-tandem mass spectrometry

A sensitive and robust multiclass analytical method was established to simultaneously determine 55 antibiotics in aquatic products through liquid chromatography-tandem mass spectrometry. A simple one-step purification process was successfully developed, which combined post-acidic acetonitrile extraction directly by an enhanced matrix removal cartridge. This approach eliminated the need for solvent transition. The established method for 55 antibiotics achieved an excellent linear relationship with R2 values ≥ 0.9921 in the range of 0.05-200 μg/L. The quantitation limits ranged within 0.04-5.0 μg/kg. Satisfactory recoveries (76.2%-99.7 %) were achieved with the relative standard deviations below 13.9 %. Furthermore, the antibiotic residues in aquatic products were analyzed, and the health and antibiotic resistance risk assessments were conducted. Although the health risks of target antibiotics were acceptable, a resistance risk was observed. Therefore, monitoring antibiotic residue levels in aquatic products requires considerable attention and further research to ensure the quality of marine products and consumer safety.

Simultaneous determination of 13 sulfonamides at trace levels in soil by modified QuEChERS with HPLC-MS/MS

The pretreatment of samples was vital for enhancing the sensitivity and accuracy of analytical methods. An efficient and sensitive method, based on modified QuEChERS with high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) for the simultaneous determination of the 13 sulfonamides (SAs) in soil, was developed. After extraction by sonication with methanol, the clean-up procedure was achieved using QuEChERS with a primary secondary amine (PSA). The quantification of the 13 SAs was performed by HPLC-MS/MS in electrospray ionization (ESI) and multiple reaction monitoring (MRM) modes. Under optimized conditions, the standard solution exhibited good linearity within the range of 0.01-0.5 μg mL-1. The limits of detection and the limits of quantification of the developed method were 0.007-0.030 μg kg-1 and 0.022-0.101 μg kg-1, respectively. The spiked recoveries for the 13 SAs were in the range of 74.5-111.7% with RSD less than 15%. Furthermore, the developed method was successfully applied for the determination of SAs in real soil samples. The above results showed that the proposed method would be an ideal analytical method for SAs in environmental ecological research.

Determination of Antibiotic Residues in Aquaculture Products by Liquid Chromatography Tandem Mass Spectrometry: Recent Trends and Developments from 2010 to 2020

The issue of antibiotic residues in aquaculture products has aroused much concern over the last decade. The residues can remain in food and enter the human body through the food chain, posing great risks to public health. For the safety of foods and products, many countries have issued maximum residue limits and banned lists for antibiotics in aquaculture products. Liquid chromatography tandem mass spectrometry (LC/MS/MS) has been widely used for the determination of trace antibiotic residues due to its high sensitivity, selectivity and throughput. However, considering its matrix effects during quantitative measurements, it has high requirements for sample pre-treatment, instrument parameters and quantitative method. This review summarized the application of LC/MS/MS in the detection of antibiotic residues in aquaculture products in the past decade (from 2010 to 2020), including sample pre-treatment techniques such as hydrolysis, derivatization, extraction and purification, mass spectrometry techniques such as triple quadrupole mass spectrometry and high-resolution mass spectrometry as well as status of matrix certified reference materials (CRMs) and matrix effect.

Simultaneous determination of pharmaceuticals and metabolites in fish tissue by QuEChERS extraction and UHPLC Q/Orbitrap MS analysis

In recent years, the occurrence, fate, and adverse effects of pharmaceutically active compounds (PhACs) in aquatic organisms have become a noteworthy issue. In the present study, a rapid and sensitive multiresidue analytical method was developed for the determination of 18 parent PhACs and 5 metabolites in sea bream (Sparus aurata), by combining a modified QuEChERS (quick, easy, cheap, effective, rugged and safe) procedure with ultra-high performance liquid chromatography-Orbitrap-mass spectrometry (UHPLC-Orbitrap-MS). The method development involved optimization of extraction solvent, extraction salts, clean-up sorbents, and amount of sample evaluation, while identification on Orbitrap MS was based on accurate mass and further confirmation with MS/MS fragmentation. The developed method was validated, and linearity was higher than 0.99. Recoveries in all cases ranged between 62 and 107% (at 10, 50, and 100 ng g^-1), while intra-day and inter-day precision, expressed as relative standard deviation, RSD, was lower than 4% and 7%, respectively. In addition, limits of quantification (LOQs) ranged between 0.5 and 19 ng g^-1. The compounds presented a low matrix effect, between - 13 and 4%, while the expanded uncertainty U% estimated at the three spiking levels 10, 50, and 100 ng g^-1 was found below 49% in all cases. Finally, the validated method was applied to sea bream samples from an aquaculture farm located in the Mediterranean Sea, with one positive finding for the antibiotic trimethoprim at a concentration of 26 ng g^-1, presenting negligible human health risk.

Magnetic solid-phase extraction based on carbon nanotubes for determination of sulfamethoxazole, acetyl sulfamethoxazole and aditoprim residues in edible swine tissues with liquid chromatography tandem mass spectrometry

Sulphonamides (SAs) are widely used in animal husbandry. In our work, based on multi-walled carbon nanotubes, a novel residue method was developed for highly sensitive and determination trace levels of sulfamethoxazole, acetyl sulfamethoxazole and aditoprim in edible swine tissues by LC-MS/MS with magnetic solid-phase extraction. The samples were extracted using 2% ammoniated acetonitrile and purified by magnetic solid phase extraction (MSPE). Under the optimal conditions, good linearity was obtained ranging from 5 to 160 μg kg^-1. The limits of detection (LOD) and quantification (LOQ) were 2 μg kg^-1 and 5 μg kg^-1 respectively. The average recoveries were 73.9-94.8% at different spiking levels. The inter-day RSDs were 6.2-10.7% and the intra-day RSDs were 2.4-5.4%. MSPE based on multi-walled carbon nanotubes was a simple and efficient method to enrich and separate the analyses and could be successfully applied for extraction of sulfamethoxazole, acetyl sulfamethoxazole and aditoprim residues in swine tissues.

Simultaneous determination of vanillin, ethyl vanillin and methyl vanillin in Chinese infant food and other dairy products by LC-MS/MS

An efficient and simple method for determining vanillin, methyl vanillin and ethyl vanillin in milk and dairy products was developed using a liquid-liquid extraction (LLE) procedure coupled to high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). Different extraction procedures were tested and optimised by spiking three vanillin compounds into a blank matrix in which none of any food additives were detected, and the extraction with acetonitrile solution and n-hexane as cleaning sorbent allowed an efficient recovery of 87.6-101.7% with RSDs less than 5%. The limit of detection (LOD) ranged from 6.2 to 20.1 μg/kg. High sensitivity, accuracy and selectivity were found for the in-house validated method, which can eliminate the interferences from complicated matrices effectively, and fulfil the quality criteria for routine laboratory application for real samples. The developed method was then finally applied to screen the three analytes in 65 milk and dairy products including infant formula milk powders from local markets to check for compliance with Chinese Regulation. Concentrations of the total vanillin and ethyl vanillin ranged from 0.0323 to 246.3 mg/kg, which is within the limits of Chinese regulations.

Determination of sulfonamide antibiotics in fish and shrimp samples based on magnetic carbon nanotube dummy molecularly imprinted polymer extraction followed by UPLC-MS/MS

In this study, a novel purification method using magnetic solid-phase extraction (MSPE) based on magnetic carbon nanotube dummy molecularly imprinted polymer (MCNTMIP) nanocomposite was investigated for separation and enrichment of sulfonamide antibiotics (SAs) in fish and shrimp samples. The MCNTMIP nanocomposite was successfully synthesized by applying carbon nanotubes as supporting template, methacrylic acid as functional monomer, sulfabenzamide as the dummy template for SAs, and ethylene glycol dimethacrylate as crosslinking agent, then was characterized by Fourier-transform infrared spectrometry and vibrating sample magnetometry. The adsorption performance of MCNTMIP was evaluated by binding experiments, including static adsorption, kinetic adsorption, and selectivity recognition study. The results confirmed that an imprinted polymer layer was successfully constructed on the surface of the MCNTMIP and this sorbent has advantages of simple magnetic separation, specific molecular recognition, and high adsorption capacity. Combined with ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS), we developed a rapid, sensitive, efficient MSPE method for detecting SAs analytes. Under the optimal conditions, the limits of detection were low to 0.1 μg/kg, and the recoveries of SAs analytes were ranged between 90.2 and 99.9%. In addition, the precision values were ranged between 0.5 and 9.1%. This method was successfully applied to analyze SAs in fish and shrimp samples with satisfactory recoveries.

Hydrophilic interaction liquid chromatography coupled to quadrupole time-of-flight mass spectrometry as a potential combination for the determination of sulfonamide residues in complex infant formula matrices

An accurate, sensitive and selective analytical method is proposed for sulfonamide residues analysis in infant formulas based on hydrophilic interaction liquid chromatography (HILIC) and quadrupole time-of-flight mass spectrometry in full scan mode. The sample preparation approach involves low-temperature lipid precipitation followed by dispersive solid-phase extraction with PSA and C₁₈ sorbents, which was successfully optimized using Plackett-Burman design. In order to achieve high analytical sensitivity, the influence of HILIC conditions on sulfonamide ionization was investigated, such as the mobile phase composition, buffer concentration, and sample diluent for injection. The method performance characteristics, including linearity (range 5-120 µg kg^-1), reliable limits of quantification (between 5 and 20 µg kg^-1), recovery (72.9-109.2%) and precision (coefficient of variation values ≤ 19.8%) under repeatability and within-laboratory reproducibility conditions, were in accordance with the Codex Alimentarius Commission CAC/GL 71-2009 for quantitative analytical methods for veterinary drug residues in foods. Moreover, adequate identification of the compounds was provided with accurate mass measurement of both precursor and fragment ions in one single run. Finally, the developed method was applied to thirty-five powdered milk-based infant formula samples available in the Brazilian market.

An environmentally friendly strategy for determining organic ultraviolet filters in seawater using liquid-phase microextraction with liquid chromatography-tandem mass spectrometry

Benzophenone-3, benzophenone-8, and 4-methylbenzylidene camphor are used in sunscreens because they can protect the skin from UV radiation. The widespread use of organic UV filters may mean that they directly or indirectly enter seawater during recreational activities or through sewage discharge. In this study, a simple and efficient method using 1-octanol:isooctane (2:8, v/v) as an extraction solvent and liquid chromatography-electrospray tandem mass spectrometry was developed to measure trace levels of organic UV filters in seawater samples. This proposed method proved to be a highly sensitive, low-cost, and green analytical tool that requires minimal sample preparation. The method was validated and it exhibited favorable performance as well as acceptable accuracy (67 to 115%), precision (2.1 to 7.3%), coefficients of determination (0.9952 < R² < 0.9987), sensitivity (limits of quantification [3.3 to 5.7 ng L^-1]), and an acceptable matrix effect (87 to 99%). This methodology was successfully applied to analyze seawater taken from Kenting National Park located in the Hengchun Peninsula of southern Taiwan. Benzophenone-3 was detected at all sampling sites and at a higher concentration than the other organic UV filters. The highest concentration of benzophenone-3 was 514.6 ng L^-1 in a sample collected from Baisha Beach.

Trends in sensitive detection and rapid removal of sulfonamides: A review

Sulfonamides in environmental water, food, and feed are a major concern for both aquatic ecosystems and public health, because they may lead to the health risk of drug resistance. Thus, numerous sensitive detection and rapid removal methodologies have been established. This review summarizes the sample preparation techniques and instrumental methods used for sensitive detection of sulfonamides. Additionally, adsorption and photocatalysis for the rapid removal of sulfonamides are also discussed. This review provides a comprehensive perspective on future sulfonamide analyses that have good performance, and on the basic methods for the rapid removal of sulfonamides.

A simple and high-throughput method for multiresidue and multiclass quantitation of antimicrobials in pangasius (Pangasionodon hypophthalmus) fillet by liquid chromatography coupled with tandem mass spectrometry

The development and validation of a throughput method for the determination of 25 antibacterial drugs (two β-lactams, eight quinolones, two macrolides, five sulfonamides, trimethoprim, four tetracyclines and three amphenicols) in pangasius fish muscle by LC-MS/MS were performed. A simple, efficient and fast extraction procedure was developed using acetonitrile and a 0.1 M EDTA solution as solvents for extraction. All compounds were determined in a single run, and chromatographic separation was achieved using a Zorbax SB C18 column with a mobile phase comprised of purified water +0.1% formic acid (A) and acetonitrile +0.1% formic acid (B) in a linear gradient program. The method was validated aαording to the requirements of European Decision 2002/657/EC. To quantify the analytes, matrix-matched analytical curves were constructed with spiked blank tissues and showed linearity (r²) higher than 0.99. For all analytes, the precision and accuracy were determined at the levels of 3 ng/g (low), 10 ng/g (low-middle), 50 ng/g (high-middle) and 100 ng/g (high). The precision (CV%) was lower than 18.6% and the accuracy (determined as recovery) was between 65% and 119%. The limit of quantitation was 3.0 ng/g, with the exception of chloramphenicol, which was 0.3 ng/g, and amoxicillin and doxycycline, which were 10 ng/g. The method was successfully applied to analyze pangasius muscle samples from Vietnam available at the Brazilian retail market, and 5 out of 40 samples showed the presence of low-residue levels of enrofloxacin and, consequently, must be considered out of conformity. It is recommended that competent authorities should avoid the commercialization of pangasius fillet contaminated with residues of this veterinary drug.

Rapid Detection of the Antibiotic Sulfamethazine in Pig Body Fluids by Paper Spray Mass Spectrometry

We report herein a practical method for nonlethal detection of the antibiotic sulfamethazine in pig body fluids via the combination of simple extraction and paper spray mass spectrometry (PS-MS). This method requires minimal sample preparation while still providing high sensitivities and accuracies in complex matrices including pig whole blood (LOD = 7.9 μg/L; recovery = 95.4-103.7%), pig serum (LOD = 11.5 μg/L; recovery = 103.2-106.2%), and synthetic urine (LOD = 11.2 μg/L; recovery = 99.1-103.2%). Given a known correlation between the level of sulfamethazine in body fluids and edible tissues, this method shows great promise as a practical and nonlethal solution for rapid testing of the drug, which can substantially aid managerial decision in the livestock industry.

Determination of sulfamonomethoxine in tilapia (Oreochromis niloticus × Oreochromis mossambicus) by liquid chromatography-tandem mass spectrometry and its application pharmacokinetics study

A precise and reliable analytical method to measure trace levels of sulfamonomethoxine (SMM) and N⁴-acetyl metabolite in tilapia samples using liquid chromatography-tandem mass spectrometry was developed. Optimized chromatographic separation was performed on C18 reversed-phase columns using gradient elution with methanol and 5 mmol/L of an ammonium acetate aqueous solution (adjusted to pH 3.5 using formic acid). This study investigated the pharmacokinetic properties and tissue distribution of SMM and its major metabolite N⁴-acetyl sulfamonomethoxine (AC-SMM) in tilapia after a single dose of 100 mg kg⁻¹ body weight of orally administered SMM. Blood and tissues were collected between 0.5 and 192 h with 14 total sampling time points. SMM was rapidly absorbed, and extensively distributed in the bile and liver through systemic circulation. Enterohepatic circulation of SMM was observed in the tilapia body. Acetylation percentages were 45% (blood), 90% (liver), 62% (kidney), 98% (bile), and 52% (muscle). High concentrations of AC-SMM accumulated in the tilapia bile. At 192 h, AC-SMM concentration in the bile remained at 4710 μg kg⁻¹. The k_e value of AC-SMM (0.015 h⁻¹) in the blood was lower than that of SMM (0.032 h⁻¹). This study demonstrated effective residue monitoring and determined the pharmacokinetic properties of SMM and AC-SMM in tilapia.

Rapid screening of sulfonamides in dietary supplements based on extracted common ion chromatogram and neutral loss scan by LC-Q/TOF-mass spectrometry

There is an increasing amount of dietary supplements that are adulterated with diuretics and anti-diabetic drugs; this has become a global problem due to the wide distribution of dietary supplements and the serious negative health effects of the adulterants. In this study, a rapid screening method was developed for detection and confirmation of 35 sulfonamides in supplements by ultra-high performance liquid chromatography quadrupole/ time of flight mass spectrometry. For effective extraction of sulfonamides from dietary supplements, four extraction protocols including HLB and WAX solid-phase extraction, Quick Easy Cheap Effective Rugged and Safe method, and pH-controlled liquid–liquid extraction were evaluated, and pH-controlled liquid–liquid extraction method was shown to be the most effective with high recovery efficiency and low matrix effect. Rapid separation of 35 sulfonamides was achieved with the UHPLC C18 column (150 × 2.1 mm, 1.7 um) within 7 min using ammonium acetate aqueous solution (pH 8) and acetonitrile as the mobile phase. From the MS/MS spectra of sulfonamides, common ions (m/z 77.9650 [SO₂N]⁻ and m/z 79.9812 [SO₂NH₂]⁻) and neutral molecule loss fragments (HCl and SO₂) were observed according to their structural characteristics. Extracted common ion chromatograms and neutral loss scan of these characteristic fragments could effectively apply for rapid screening of sulfonamides in various types of supplements. A reduced mass tolerance window of ±5 ppm was useful for detecting targeted and untargeted sulfonamides and could avoid false positive and false negative results. Overall calibration curves within dynamic range for all targets were shown to be linear with a correlation coefficient R² > 0.995 and limits of detection ranged from 0.04 to 11.18 ng/g for all sulfonamides. The established method was successfully applied for screening and confirmation of sulfonamides in various supplements. The developed method will be helpful for the identification of sulfonamide diuretics and anti-diabetics in dietary supplements, promoting public health and consumer safety.

A Cu(II)-anchored unzipped covalent triazine framework with peroxidase-mimicking properties for molecular imprinting-based electrochemiluminescent detection of sulfaquinoxaline

The authors describe a method of electrochemiluminescent quantitation of the antibiotic sulfaquinoxaline (SQX). It relies on the use of a molecularly imprinted polymer and a Cu(II)-anchored unzipped covalent triazine framework (UnZ-CCTF) with excellent dispersibility, electrical conductivity, and peroxidaze-like activity. The framework was prepared by unzipping a covalent triazine framework under retention of basic triazine units. It was morphologically and structurally characterized by a range of instrumental techniques. The excellent peroxidase-mimicking effect of UnZ-CCTF on the electrochemiluminescence of the luminol/H₂O₂ system was exploited to design an ultrasensitive SQX assay with a 1.0-20 pM detection range and a detection limit of 0.76 pM (at 3δ/m). The technique was used for SQX quantitation in spiked milk samples, achieving recoveries of 94.0-104.8%. Graphical abstract Scheme of the sulfaquinoxaline molecularly imprinted electrochemiluminescence sensor based on Cu-anchored unzipped covalent triazine frameworks.

Novel electrochemical aptasensor for ultrasensitive detection of sulfadimidine based on covalently linked multi-walled carbon nanotubes and in situ synthesized gold nanoparticle composites

In the current study, a sensitive electrochemical sensing strategy based on aptamer (APT) for detection of sulfadimidine (SM₂) was developed. A bare gold electrode (AuE) was first modified with 2-aminoethanethiol (2-AET) through self-assembly, used as linker for the subsequent immobilization of multi-walled carbon nanotubes and gold nanoparticle composites (MWCNTs/AuNPs). Then, the thiolated APT was assembled onto the electrode via sulfur-gold affinity. When SM₂ existed, the APT combined with SM₂ and formed a complex structure. The specific binding of SM₂ and APT increased the impedance, leading to hard electron transfer between the electrode surface and the redox probe [Fe(CN)₆]^3-/4- and producing a significant reduction of the signal. The SM₂ concentration could be reflected by the current difference of the peak currents before and after target binding. Under optimized conditions, the linear dynamic range is from 0.1 to 50 ng mL^-1, with a detection limit of 0.055 ng mL^-1. The sensor exhibited desirable selectivity against other sulfonamides and performs successfully when analyzing SM₂ in pork samples. Graphical abstract A new electrochemical biosensor for ultrasensitive detection of sulfadimidine (SM₂) by using a gold electrode modified with MWCNTs/AuNPs for signal amplification and aptamer (APT) for selectivity improvement.

Determination of Sulfonamides in Chicken Muscle by Pulsed Direct Current Electrospray Ionization Tandem Mass Spectrometry

A simple and rapid approach for the simultaneous detection of trace amounts of six sulfonamides in chicken muscle was developed using pulsed direct current electrospray ionization tandem mass spectrometry (pulsed-dc ESI-MS/MS). The pretreatment of chicken muscle samples consisted of two steps: acetonitrile extraction and n-hexane delipidation. Sulfonamides do not need to be derivatized or chromatographed prior to pulsed-dc ESI-MS/MS. The factors affecting the performance of pulsed-dc ESI-MS/MS were studied. Under optimum conditions, the quantitative performance of pulsed-dc ESI-MS/MS was validated according to European Union Decision 2002/657/EC, and the sensitivity of pulsed-dc ESI-MS/MS was 3 times higher than that of ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The limits of detection obtained by pulsed-dc ESI-MS/MS were in the range of 0.07-0.11 μg/kg. The proposed method was simple, rapid, and sensitive, and was successfully used for quantitation and rapid screening of sulfonamides in real chicken muscle samples.

Rapid Determination of Trace Multiresidues of 18 Sulfonamides in Chicken Eggs Using a Modified QuEChERS Method Coupled with Ultrahigh Performance Liquid Chromatography

A modified QuEChERS method was used and an ultrahigh performance liquid chromatography (UHPLC) method was developed for the rapid determination of 18 kinds of sulfonamide residues in chicken eggs. Sample preparation and cleanup conditions were carefully evaluated, and factors such as the adsorbent type and adsorption condition were key parameters in improving the cleanup. The modified QuEChERS method removed matrix interferences, and the sensitivity of the method increased about 5% for recovery and efficiency of the method. Under the optimized UHPLC method with UV detection, all 18 sulfonamide residues were simultaneously separated and rapidly identified within 15 min. The qualitative and quantitative method limits of the 18 sulfonamide residues were 2.06 to 4.12 and 6.86 to 13.7 μg·kg^-1, respectively. A close linear relationship (R² = 0.990 to 0.999) was observed within the concentration range of 0.10 to 2.25 μg·ml^-1. Recovery was satisfactory (71 to 102%) for all the sulfonamides in three standard spiked levels, with relative standard deviations of <9.7%. After the modified sample pretreatment, the speed of sample pretreatment, purification, and analysis efficiency were all significantly increased. This method is suitable for the rapid detection of multisulfonamide residues in chicken eggs and other animal-derived foods.

Nontargeted Screening Method for Illegal Additives Based on Ultrahigh-Performance Liquid Chromatography-High-Resolution Mass Spectrometry

Identification of illegal additives in complex matrixes is important in the food safety field. In this study a nontargeted screening strategy was developed to find illegal additives based on ultrahigh-performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS). First, an analytical method for possible illegal additives in complex matrixes was established including fast sample pretreatment, accurate UHPLC separation, and HRMS detection. Second, efficient data processing and differential analysis workflow were suggested and applied to find potential risk compounds. Third, structure elucidation of risk compounds was performed by (1) searching online databases [Metlin and the Human Metabolome Database (HMDB)] and an in-house database which was established at the above-defined conditions of UHPLC-HRMS analysis and contains information on retention time, mass spectra (MS), and tandem mass spectra (MS/MS) of 475 illegal additives, (2) analyzing fragment ions, and (3) referring to fragmentation rules. Fish was taken as an example to show the usefulness of the nontargeted screening strategy, and six additives were found in suspected fish samples. Quantitative analysis was further carried out to determine the contents of these compounds. The satisfactory application of this strategy in fish samples means that it can also be used in the screening of illegal additives in other kinds of food samples.