Research progress on metabolites of nitrofurazone in aquatic products.

The carcinogenic and teratogenic risks of nitrofurazone (NFZ) led to its restriction in aquatic products. Semicarbazide (SEM), one of its metabolites, is a primary focus of modern monitoring techniques. However, the SEM residue in aquatic products is believed to be formed through endogenous mechanisms, especially for aquatic crustaceans. In this article, we will discuss the source of SEM, including its usage as an antibiotic in aquatic products (nitrofurazone), its production during food processing (azodicarbonamide and hypochlorite treatment), its occurrence naturally in the body, and its intake from the environment. SEM detection techniques were divided into three groups: derivatization, extraction/purification, and analytical methods. Applications based on liquid chromatography and its tandem mass spectrometry, immunoassay, and electrochemical methods were outlined, as were the use of various derivatives and their assisted derivatization, as well as extraction and purification techniques based on liquid-liquid extraction and solid-phase extraction. The difficulties of implementing SEM for nitrofurazone monitoring in aquatic products from crustaceans are also discussed. Possible new markers and methods for detecting them are discussed. Finally, the present research on monitoring illicit nitrofurazone usage through its metabolites is summarised, and potential problems that need to be overcome by continuing research are proposed with an eye toward giving references for future studies.

[Exposure Level and Risk Impact Assessment of Pesticides and Veterinary Drugs in Aquaculture Environment].

To explore the exposure level of pesticides and veterinary drugs in an aquaculture environment and its impact on the ecological environment, this study took the aquaculture environment in Shanghai as an example, and samples of water, sediment, and inputs from 40 major aquaculture farms were collected from July to September 2022. The types and contents of pesticides and veterinary drugs were screened using high-performance liquid chromatography-electrostatic field orbital ion trap mass spectrometry, and the risk quotient (RQ) method was used to assess the ecological risk of pesticide contamination in water and sediment. The results showed that 13 drugs were screened out from 204 samples (72 samples of water, 72 samples of mud, and 60 samples of input), namely, chlorpromazine, carbendazim, thiophanate, diazepam, florfenicol, simazine, amantidine, diazepam, trimethoprim, ciprofloxacin, ofloxacin, mebendazole, and enrofloxacin. Among them, 12 species were found in water samples with concentrations ranging from 0.016 µg·L-1 to 2.084 µg·L-1. The concentrations of seven species in the mud samples ranged from 0.018 µg·kg-1 to 23.101 µg·kg-1. The results showed that there were four types of inputs, ranging from 1.979 µg·kg-1 to 101.940 µg·kg-1. Seven drugs were found in both water and sediment. The risk quotient (RQ) results showed that there were some high and middle risks in both water and sediment samples of aquaculture farms, and the ecological risks of carbendazim were the highest in both water and sediment samples of aquaculture farms; the RQ values were 3.848 and 1.580, respectively, indicating high risk. It is suggested to strengthen the control and management of exogenous pesticides and veterinary drugs in aquaculture environments to protect the ecosystem health of the aquaculture environment.

One step cleanup of 160 pesticides and veterinary drugs in aquatic products using melamine-based automatic pressure filtration purification method combined with HPLC-MS/MS.

A 15-channel pressure filtration purification method was presented for high throughput sample preparation of aquatic products. A cost-effective device was constructed and melamine sponge was selected as the cleanup sorbent. Upon interfacing with HPLC-MS/MS, the analytical procedure demonstrated its suitability for quantifying 160 pesticides and veterinary drug residues in aquatic products such as fish, shrimp, and crab. The method achieved sample recoveries ranging from 61.3 to 124.9 %. The detection limits were established between 0.5 and 1.0 µg/kg, while the quantitation limits were confirmed to be within the range of 1.0-2.0 µg/kg. The method was applied to quantify the pesticide and veterinary drug residues in mostly consumed aquatic products from five coastal provinces in China. The results showed significant differences between different aquatic products in the concentrations of pesticide and veterinary drug residues, implying the necessity of supervision for the accurate determination of pesticides and veterinary drugs.

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.

Determination of earthy-musty odors in tap water by gas chromatography‒mass spectrometry with silica solid-phase extraction.

This research aimed to develop an effective method for detecting semivolatile earthy-musty odors without using the conventional sample processing equipment used for volatile compounds. The concurrent isolation of 2-methylisoborneol (2-MIB), trans-1,10-dimethyl-trans-9-decalol (geosmin, GSM), 2-isopropyl-3-methoxy pyrazine (IPMP), and 2-isobutyl-3-methoxy pyrazine (IBMP) in tap water was successfully achieved by employing a combination of n-hexane liquid‒liquid extraction (LLE) and silica solid-phase extraction (SPE) techniques. Gas chromatography-mass spectrometry (GC-MS) was utilized for the identification of these targets, with the inclusion of borneol (BN) as an internal reference. This robust method was optimized and validated. It was found that the method showed good linearity in the range of 0.5-100 ng/mL and produced good recoveries (84.6 %-103 %) with satisfactory relative standard deviations (1.50 %-10.1 %). The determined limits of detection (LODs) for the group of four substances were found to vary from 0.3 to 0.9 ng/L, whereas the limits of quantitation (LOQs) exhibited variations between 1 and 3 ng/L. The subsequent implementation of this methodology to evaluate the four previously described off-flavor chemicals in tap water resulted in satisfactory results.

Novel filter-press single-step cleanup approach facilitated rapid screening and accurate quantification of 112 veterinary drugs in aquatic products.

In this study, a novel filter-press cleanup column was developed as a single-step cleanup approach for the rapid screening and quantification of 112 veterinary drugs in fish samples. Fish muscle samples were extracted with acetonitrile and ethyl acetate, sequentially. After concentration and reconstitution, N-propylethylenediamine (PSA) sorbent, packed in filter-press column, allows rapid single-step cleanup operation, while UHPLC-Q-Orbitrap-HRMS provides high-precision mass information in multi-residue screening. Under optimum settings, the detection and quantification limits were validated at 0.5 and 2.0 µg·kg-1, for all analytes, respectively. The ranges of recoveries were from 35.3 to 138.4%. Most of these target analytes (82%) could be measured with recoveries between 60 and 130%, and intra-day RSDs ranging from 1.9 to 26.1%. This method was further applied to evaluate the residual of veterinary drugs in fish samples from four cities in China, and results demonstrated its practicability for multi-residue monitoring veterinary residues for food safety administration.

Rapid Sample Enrichment, Novel Derivatization, and High Sensitivity for Determination of 3-Chloropropane-1,2-diol in Soy Sauce via High-Performance Liquid Chromatography-Tandem Mass Spectrometry.

A novel, simplified derivatization method and a rapid sample preparation process using carbon yarn as a sorbent for the determination of 3-chloropropane-1,2-diol (3-MCPD) in soy sauce via high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed. 3-MCPD was first enriched and purified with carbon yarn and then eluted with a methanol-water solution. Subsequently, the analyte underwent derivatization with p-(dimethylamino)-phenol for sensitive detection via HPLC-MS/MS. The limit of detection and the limit of quantitation for 3-MCPD were validated to be 0.5 and 1.0 µg/kg, respectively. Spiking experiments showed recoveries between 83 and 94%, with a relative standard deviation of ≤10%. The method was further validated with a certified reference material. Furthermore, 11 real soy sauce samples from local markets were tested by using this method. These results reveal the widespread 3-MCPD contamination. Consequently, this study offers a preferable alternative for the sensitive, accurate, and precise determination of 3-MCPD in soy sauce.

Multi-Residue Screening of Pesticides in Aquatic Products Using High-Performance Liquid Chromatography-Tandem High-Resolution Mass Spectrometry.

Pesticide residues in aquatic products are of great concern due to the risk of environmental transmission and their extensive use in aquaculture. In our work, a quick screening approach was developed for the qualitative and semi-quantitative screening of 87 pesticide residues in aquatic products. The sample preparation was investigated, including extract solvent, extract methods, buffer salts, lipid removal, cleanup materials and filter membranes for aquatic products. Samples were extracted using a modified QuEChERS procedure, and two clean-up procedures were developed for UHPLC-Q/Orbitrap MS analysis based on the fat content of the aquatic products. The screening detection limits for all studied pesticides were distributed between 1 and 500 µg/kg in the three representative matrices. Seventy-one pesticides could be analyzed with a screening limit between 1 and 25 µg/kg in grass carp and crayfish, sixty-one pesticides could be screened for limits between 1 and 50 µg/kg in crab. The accuracy results showed that recoveries ranged from 50 to 120% for 60, 56 and 52 pesticides at medium-level for grass carp, crayfish and crab, respectively. At high spiking levels, 74, 65 and 59 pesticides were recovered within the range of 50-120% for the three matrices, respectively. The relative standard deviations of most compounds in different matrices were less than 20%. With this method, the local farmed aquatic products were tested for pesticide residues. In these samples, ethoxyquinoline, prometryn and phoxim were frequently detected. The majority of these confirmed compounds did not exceed 2.00 µg/kg. A grass carp with trichlorfon at 4.87 µg/kg and two carps with ethoxyquinoline at 200 µg/kg were detected, indicating the potential dietary risk.

Improved LC/MS/MS Quantification Using Dual Deuterated Isomers as the Surrogates: A Case Analysis of Enrofloxacin Residue in Aquatic Products.

Extensive and high residue variations in enrofloxacin (ENR) exist in different aquatic products. A novel quantitative method for measuring ENR using high-performance liquid chromatography-tandem mass spectrometry was developed employing enrofloxacin-d5 (ENR-d5) and enrofloxacin-d3 (ENR-d3) as isotope surrogates. This reduced the deviation of detected values, which results from the overpass of the linear range and/or the large difference in the residue between the isotope standard and ENR, from the actual content. Furthermore, high residue levels of ENR can be directly diluted and re-calibrated by the corresponding curve with the addition of high levels of another internal surrogate without repeated sample preparation, avoiding the overflow of the instrument response. The validation results demonstrated that the method can simultaneously determine ENR residues from MQL (2 µg/kg) to 5000 × MQL (method quantification limit) with recoveries between 97.1 and 106%, and intra-precision of no more than 2.14%. This method realized a wide linear calibration range with dual deuterated isomers, which has not been previously reported in the literature. The developed method was successfully applied to the analysis of ENR in different aquatic products, with ENR residue levels varying from 108 to 4340 µg/kg and an interval of precision in the range of 0.175~6.72%. These results demonstrate that batch samples with a high variation in ENR residues (over the linear range with a single isotope standard) can be detected by the dual isotope surrogates method in a single sample preparation process.

H-beta zeolite-based dispersive solid-phase strategy for the multi-residue determination of pesticides.

In this work, electrostatic interactions, hydrogen bonding and other interactions between a variety of pesticides and H-beta zeolite are discussed based on thermodynamics (Gibbs free energy, enthalpy, and entropy). Combined with the physical properties of the target compounds (octanol-water partition coefficient and molar volume), the characteristics of the physical adsorption on the synthetic zeolite were analyzed, the results of H-beta zeolite adsorption showed that the adsorption rate had a nonlinear relationship with the physical properties, and the adsorption reaction was dominated by the adsorption on the surface and in the pores of the H-beta zeolite. Based on the principle of zeolite adsorption, the parameters of absorbent amount, adsorption time, sample pH, ion strength, sample volume and desorption solvent were optimized, a vortex-assisted dispersive solid-phase extraction procedure coupled with liquid chromatography-tandem mass spectrometry was developed for the analysis of multiple pesticides in surface water. The sample was adjusted by phosphate buffer or hydrochloric acid to pH 4, then adsorbed by 50 mg of zeolite within 10 min, adding 2% (g/v) sodium chloride to the solution. The absorbent was eluted with a mixture of acetonitrile-methanol containing 0.5% formic acid after separation, then filtered prior to analysis. The optimized vortex-assisted dispersive solid-phase extraction method simultaneously achieved a low adsorbent dosage, a high enrichment factor of 25, rapid pre-concentration for 30 min, a low solvent usage of 2 mL and multi-target simultaneous analysis. Method performance in terms of accuracy, precision, limit of detection, and limit of quantitation was performed to validate the reliability of the procedure. The proposed protocol achieved acceptable accuracy (recoveries between 62% and 107%), and precision (relative standard deviation < 20%). The limit of detection of the method was below 0.1 µg/L, and the limit of quantitation was 0.08 µg/L or 0.2 µg/L. The results indicated that zeolite is a promising adsorbent with high adsorption capacity. It has the advantages of being a fast, simple, green and economical method for determining residual pesticides in water.

Pharmacokinetics studies of eugenol in Pacific white shrimp (Litopenaeus vannamei) after immersion bath.

BACKGROUND: Eugenol is the most commonly used plant anesthetic to relieve the stressors during various aquaculture procedures. This study aims to investigate the pharmacokinetics of eugenol in Pacific white shrimp by immersion baths in a simulated transportation. RESULTS: The pharmacokinetics of eugenol were firstly investigated in Pacific white shrimp by immersion baths of 300 mg L- 1 eugenol over 5 min (Treatment 1), 10 mg L- 1 eugenol during 24 h (Treatment 2) and a sequential immersion administration (Treatment 3). Concentrations of eugenol in hemolymph, hepatopancreas, and muscle were determined using Gas chromatography-tandem mass spectrometry (GC-MS/MS). After immersion bath of Treatment 1, the elimination half-life (t1/2z) values are 1.3 h and 11 h for hepatopancreas and muscles, indicating the rapid absorption and elimination of eugenol in shrimp. Under the Treatment 2 administration, the eugenol peak concentration is 6527.9 µg/kg in muscle, followed by 402.8 µg/kg in hepatopancreas, with the lowest concentration of 37.9 µg/L in hemolymph. Area under the curve (AUC0-∞) values lie in the order of muscle > hepatopancreas > hemolymph, suggesting that eugenol tends to accumulate in muscle by the immersion administration. Moreover, the average residence time (MRT0-∞) values of 38.6, 23.0 and 115.3 h for hemolymph, hepatopancreas and muscle are achieved, which may indicate that hepatopancreas is the main organ for elimination of eugenol. After combining the conditions in a sequential bath immersion of eugenol (Treatment 3), the maximum concentration (Cmax) values of eugenol are higher than those achieved in Treatment 2, indicating that accumulation of eugenol happened in haemolymph, hepatopancreas and muscle. In addition, the corresponding t1/2z values are 4.7, 14.9 and 47.6 h, respectively, suggesting the faster elimination from the tissues following sequential administration. After the immersion bath, eugenol concentrations in muscle of Pacific white shrimp are lower than 2.5 mg/kg at 2 h, 48 h and 24.5 h in Treatment 1 ~ 3. CONCLUSIONS: A withdrawal period of 2 h, 48 h and 24.5 h following a 300 mg L- 1 of eugenol over a 5-min, 10 mg L- 1 eugenol concentration during a 24-h and combined conditions in a sequential immersion bath were suggested.

Combination of pipette tip solid phase extraction and high performance liquid chromatography for determination of plant growth regulators in food samples based on the electrospun covalent organic framework/polyacrylonitrile nanofiber as highly efficient sorbent.

Facile and sensitive determination of plant growth regulators (PGRs) in food samples is important but still remains great challenge. Herein, a pipette tip solid phase extraction (PT-SPE) method was developed for fast and sensitively detecting PGRs. The PT-SPE adsorbent was prepared by integrating a novel covalent organic framework (COF) of schiff base network 3 (SNW-3) and polyacrylonitrile (PAN) through electrospinning. The SNW-3 can easily adsorb PGRs with high special affinity through electrovalent bands between the ammonium ions of SNW-3 and the carboxy groups of PGRs. The polymer of PAN acts as scaffold material for SNW-3, which can lower seepage pressure hence accelerates adsorption/desorption kinetics. By combination with HPLC-DAD, a satisfactory method was successfully developed for simultaneous determination of ten PGRs in watermelon. Good analytical performances were achieved with this proposed method, including good linearity (5-500 ng/mL) with high correlation coefficients (R ≥ 0.9981), low limits of detection (S/N = 3, 0.24-3.19 ng/mL) and limits of quantification (S/N = 10, 1.65-5.72 ng/mL), satisfactory precision (intra-day RSDs ≤ 2.7%, inter-day RSDs ≤ 3.7%), and high accuracy (recovery: 82.8-113.0%). The method developed in this study shows high potential for design of high target-affinity adsorbents for food sample preparing.

Ratiometric Fluorescence Immunoassay Based on Carbon Quantum Dots for Sensitive Detection of Malachite Green in Fish.

Malachite green (MG) is a synthetic poisonous organic compound that has been banned in many countries as a veterinary drug for aquaculture. An efficient, fast and sensitive method is urgently needed for monitoring the illegal use of malachite green (MG) in aquaculture. In this study, a novel ratiometric fluorescence immunoassay was established. Nitrogen-doped carbon quantum dots were used as ratiometric fluorescent probes with a fluorescence peak at 450 nm. Horseradish peroxidase was employed to convert o-phenylenediamine to 2,3-diaminophenazine, with a new fluorescence peak at 580 nm and a strong absorption at 420 nm. The inner filter effect between N-CQD fluorescence and DAP absorption was identified. It allows for the ratiometric detection of MG using a fluorescent immunoassay. The results demonstrated a linear ratiometric fluorescence response for MG between 0.1 and 12.8 ng·mL-1. The limit of detection of this method was verified to be 0.097 µg·kg-1 with recoveries ranging from 81.88 to 108%, and the relative standard deviations were below 3%. Furthermore, this method exhibited acceptable consistency with the LC-MS/MS results when applied for MG screening in real samples. These results demonstrated a promising application of this novel ratiometric fluorescence immunoassay for MG screening with the merits of rapid detection, simple sample preparation, and stable signal readout. It can be an alternative to other traditional methods if there are difficulties in the availability of expensive instruments, and achieve comparable results or even more sensitivity than other reported methods.

Green preparation of carbon quantum dots with wolfberry as on-off-on nanosensors for the detection of Fe3+ and l-ascorbic acid.

A green and facile hydrothermal synthesis approach is proposed for the preparation of nitrogen-doped carbon quantum dots (N-CQDs) with wolfberry. These N-CQDs were developed as a highly sensitive fluorescent 'on-off-on' switch sensor for the sensing of Fe3+ and l-ascorbic acid (AA). The N-CQDs displayed superior fluorescence characteristics of CQDs with a quantum yield up to 22%. The N-CQDs were demonstrated to selectively react with Fe3+, leading to fluorescence quenching effect, which was successfully used for the detection of Fe3+ with a limit of detection at 3 µmoL•L-1. The addition of AA is supposed to repair the surface defects, and result in the fluorescence recovery. Based on this effect, the strategy of 'on-off-on' detection of AA was established with a limit of detection at 1.8 µmoL•L-1. Furthermore, the practical application of the detection of Fe3+ lake water and AA in medical tablet was demonstrated, promising an effective and efficient 'on-off-on' nanosensor with low-cost, green synthesis for Fe3+ and AA detection.

Colorimetric Sensing with Gold Nanoparticles on Electrowetting-Based Digital Microfluidics.

Digital microfluidic (DMF) has been a unique tool for manipulating micro-droplets with high flexibility and accuracy. To extend the application of DMF for automatic and in-site detection, it is promising to introduce colorimetric sensing based on gold nanoparticles (AuNPs), which have advantages including high sensitivity, label-free, biocompatibility, and easy surface modification. However, there is still a lack of studies for investigating the movement and stability of AuNPs for in-site detection on the electrowetting-based digital microfluidics. Herein, to demonstrate the ability of DMF for colorimetric sensing with AuNPs, we investigated the electrowetting property of the AuNPs droplets on the hydrophobic interface of the DMF chip and examined the stability of the AuNPs on DMF as well as the influence of evaporation to the colorimetric sensing. As a result, we found that the electrowetting of AuNPs fits to a modified Young-Lippmann equation, which suggests that a higher voltage is required to actuate AuNPs droplets compared with actuating water droplets. Moreover, the stability of AuNPs was maintained during the processing of electrowetting. We also proved that the evaporation of droplets has a limited influence on the detections that last several minutes. Finally, a model experiment for the detection of Hg2+ was carried out with similar results to the detections in bulk solution. The proposed method can be further extended to a wide range of AuNPs-based detection for label-free, automatic, and low-cost detection of small molecules, biomarkers, and metal ions.

Determination of 6 biogenic amines in food using high-performance liquid chromatography-tandem mass spectrometry without derivatization.

A rapid and simple method for the determination of 6 biogenic amines (BAs) in food was established on HPLC-MS /MS without derivatization. Samples were extracted with 5% perchloric acid and cleaned with n-hexane for lipid removal. The analytes were separated on Waters XBridge® HILIC (150 mm × 2.1 mm, 3.5 µm) and analyzed with multiple-reaction monitoring (MRM) mode after positive electrospray ionization on HPLC-MS/MS. Good linearity with high correlation coefficient was obtained between 10-1000 µg/L for cadaverine (CAD), putrescine (PUT), tyramine (TYR) and 2-phenylethylamine (2-PHE) and between 1-100 µg/L for histamine (HIS) and tryptamine (TRY), with the detection limits of the method ranging from 0.1 mg/kg for HIS and TRY, and 1.0 mg/kg for CAD, PUT, TYR and 2-PHE, which are under the residue limit of Chinese regulation. Spiking experiments demonstrated good recoveries between 70.2-114.6%, with relative standard deviations (RSDs) between 0.44-13.01%. This method was validated for BAs determination in liquor, fermented meat products, vegetable products, soybean products, dairy products, seafood and its derived products. These results promise high feasibility for BAs monitoring in various food with easy-to-operate and fast sample preparation process, stable analysis on HPLC-MS/MS without derivatization.

Determination of Methylene Blue and Its Metabolite Residues in Aquatic Products by High-Performance Liquid Chromatography-Tandem Mass Spectrometry.

A sensitive and reliable method was developed to determine methylene blue (MB) and its metabolite residues, including azure A (AZA), azure B (AZB), and azure C (AZC) in aquatic products by HPLC-MS/MS. The samples were extracted by acetonitrile and cleaned up by alumina-neutral (ALN) cartridges. The analytes were separated on a Sunfire C18 column (150 mm × 2.1 mm, 5 µm). The method was validated according to the European criteria of Commission Decision 2002/657/CE. Good linearity between 1-500 µg/L was obtained with correlation coefficients (R2) greater than 0.99. The limit of quantification (LOQ) was 1.0 µg/kg. The average recoveries at three levels of each compound (1, 5, and 10 µg/kg) were demonstrated to be in the range of 71.8-97.5%, with relative standard deviations (RSDs) from 1.05% to 8.63%. This method was suitable for the detection of methylene blue and its metabolite residues in aquatic products.

Pesticides and risk assessment in Shanghai fruit and raw eaten vegetables.

A database of 392 pesticides established by an Ultrahigh performance liquid chromatography-tandem Q/Orbitrap high-resolution mass spectrometer (UPLC-Q/Orbitrap-HRMS) was used to screen multiple residues of pesticides in fruit and raw eaten vegetables from planting farms in Shanghai. Risk assessment was conducted with the screened results of the determined pesticides as to evaluate food safety. In 95% of the samples, one or more pesticides had a content below the maximum residue limits (MRLs) as set in the national Chinese standard. The co-occurrence of multi-residues of pesticides was more severe in peach and muskmelon, when compared with other food. All hazard index values of different groups were in the range of 0.19% to 12.3%, demonstrating that chronic dietary risk of studied fruits and raw eaten vegetables is low and the studied food samples were safe for human consumption in terms of these detected pesticides.

An Effective and Efficient Sample Preparation Method for 2-Methyl-Isoborneol and Geosmin in Fish and Their Analysis by Gas Chromatography-Mass Spectrometry.

The intensive aquaculture strategy and recirculating aquaculture system often lead to the production of off-flavor compounds such as 2-methyl-isoborneol (2-MIB) and Geosmin (GSM). The regular purge and trap extraction followed by analysis with gas chromatography-mass spectrometry (GC-MS) usually involve a complicated assembly of facilities, more working space, long sample preparation time, and headspace solid-phase microextraction (SPME). In this work, a method with easier sample preparation, fewer and simplified facilities, and without SPME on GC-MS analysis is developed for the determination of 2-MIB and GSM in fish samples. Unlike previous methods, solvent extract from samples, QuEChERS-based cleanup, and solid-phase extraction for concentration are applied. The LOD (S/N > 3) and LOQ (S/N > 10) of this method were validated at 0.6 µg/kg and 1.0 µg/kg for both 2-MIB and GSM, which are under the sensory limit (1 µg/kg). Application of this method for incurred fish samples demonstrated acceptable analytical performance. This method is suitable for large-scale determination of 2-MIB and GSM in fish samples, owing to the use of simple facility and easy-to-operate procedure, rapid sample preparation, and shorter time for GC-MS analysis without SPME.

Determination of 8 biogenic amines in aquatic products and their derived products by high-performance liquid chromatography-tandem mass spectrometry without derivatization.

A method for the determination of 8 biogenic amines in aquatic products and their derived products was established by HPLC-MS/MS without derivatization. The samples were extracted by 5% perchloric acid solution. N-hexane was used to clean the extract. The analytes were separated by a column of ACQUITY UPLC HSS T3 (100 mm × 2.1 mm, 1.8 µm), and gradient eluted with a mixed solution of (0.5% formic acid) and acetonitrile. Good linearity was obtained with correlation coefficients (R2) >0.99. This method achieved higher sensitivity (from 0.1 mg/kg for tyramine, 2-phenylethylamine and tryptamine to 1.0 mg/kg for spermidine, spermine, cadaverin, histamine and putrescine). The average recoveries were demonstrated in the range of 70.9%-113.1%, with relative standard deviations (RSDs) from 0.33% to 10.81%. This method was suitable for the detection of BAs in aquatic products and their products.