Distribution, trophic magnification and risk of trace metals and perfluoroalkyl acids in marine organisms from Haizhou Bay.

Haizhou Bay, a semi-enclosed key aquaculture area in East China, has had relatively limited research focused on trace metals and perfluoroalkyl acids (PFAAs) in its biota. This study characterized the distribution, biomagnification and health risks of selected trace metals and PFAAs in various marine organisms from Haizhou Bay. Among the species examined, zinc (Zn) was the most prevalent metal, followed by copper (Cu) and chromium (Cr), whereas cadmium (Cd), total mercury (THg), and methylmercury (MeHg) contents were relatively low. Perfluorooctane sulfonate (PFOS) was the most abundant PFAA, followed by perfluorooctanoic acid (PFOA). The calculated trophic magnification factors (TMFs) were above one for Cr, THg, MeHg, and all PFAAs except perfluorobutanoic acid (PFBA) and perfluorotetradecanoic acid (PFTeDA). Across animal groups, gastropods exhibited relatively low levels of THg, MeHg, and perfluorosulfonic acids (∑PFSAs). By comparison, fish generally had lower levels of Cd and Cu compared to other animal groups, and demersal fish had significantly higher MeHg compared to gastropods. Certain organisms, such as cephalopods and shrimps, were found to pose potential health risks due to elevated levels of Cd, while levels of other studied metals, PFOS and PFOA generally appeared to be within safe limits for human consumption. Further research is needed to assess the sources and impacts of these and other contaminants.

Study on the Rapid Limit Test for Six Sulfonamide Residues in Food Based on the TLC-SERS Method.

Sulfonamides are not only widely applied in clinics but also highly valued in animal husbandry. Recently, it has become common for sulfonamide residues to exceed the standard limits in food, which can affect human health. Current regulations limit these residues. Therefore, we constructed a new limit test method to rapidly determine the levels of sulfonamide residues. Six sulfonamides were detected using the latest method called TLC-SERS, namely, sulfamethasone (A), sulfamethazine (B), sulfadoxine (C), sulfamethoxydiazine (D), sulfamethoxazole (E), and sulfathiazole (F). The optimal conditions for SERS detection were investigated for these six drugs, and the separation effects of different TLC spreaders on them were compared. Then, we successfully established a separation system using dichloromethane-methanol-ammonia in a ratio of 5:1:0.25 (v/v/v), which provided good separation effects on the six drugs. The residues were preliminarily separated via TLC. A silver sol solution was added to the spot on the silica gel G plate at the corresponding specific shift values, and SERS detection was performed. The sample solution was placed on the spot under a 532 nm laser, and the SERS spectrum was collected and analyzed for the six sulfonamides. The results showed obvious variations in the SERS spectrum among the six sulfonamides, with the LODs being 12.5, 6.4, 6.3, 7.1, 18.8, and 6.2 ng/mL from A to F, respectively, and an RSD of <3.0%. Within 48 h, the SERS signal for each sulfonamide drug was kept stable, with an RSD of <3.0%. The detection results of 20 samples using the TLC-SERS method were consistent with those obtained by UPLC-MS/MS. The established TLC-SERS method is simple and fast, providing a useful reference for the rapid detection of residue limits in food.

[Simultaneous determination of six benzodiazepine sedatives residue in aquatic products by high performance liquid chromatography-triple quadrupole mass spectrometry].

OBJECTIVE: To establish a method for the simultaneous determination of 6 benzodiazepine sedatives residue in aquatic products by high performance liquid chromatography-triple quadrupole mass spectrometry. METHODS: The samples were extracted with acetonitrile and purified by C_(18 )solid phase extraction column. The sample solution was separated by Waters ACQUITY UPLC BEH C_(18 )column(2.1 mm×50 mm, 1.7 µm) using 0.1% formic acid and methanol as mobile phase for gradient elution, determined in multiple reaction monitoring mode and quantified by internal standard method. RESULTS: Six benzodiazepine sedatives had a good linear relationship in the range of 1.0-50.0 µg/L with r>0.9990, the limits of detection and limits of quantification were 0.3 and 1.0 µg/kg. Average recoveries for the analytes at 3 spiked levels ranged from 74.2%-108.0% with relative standard deviations of 1.1%-6.7%(n=6). CONCLUSION: The method is simple, rapid, sensitive and accurate, which is suitable for simultaneous determination of 6 benzodiazepine sedatives residue in aquatic products.

Degradation mechanism and development of detection technologies of ATP-related compounds in aquatic products: recent advances and remaining challenges.

The degradation of ATP-related compounds is an important biochemical process that reflects the freshness of aquatic products after death. There has been considerable interest in investigating the factors affecting the degradation of ATP-related compounds in aquatic products and in developing techniques to detect them. This review provides the latest knowledge on the degradation mechanisms of ATP-related compounds during the storage of aquatic products and discusses the latest advances in ATP-related compound detection techniques. The degradation mechanisms discussed include mainly degradation pathways, endogenous enzymes, and microbial mechanisms of action. Microbial activity is the main reason for the degradation of IMP and related products during the mid to late storage of aquatic products, mainly through the related enzymes produced by microorganisms. Further elucidation of the degradation mechanisms of ATP-related compounds provides new ideas for quality control techniques in raw aquatic products during storage. The development of new technologies for the detection of ATP-related compounds has become a significant area of research. And, biosensors further improve the efficiency and accuracy of detection and have potential application prospects. The development of biosensor back-end modalities (test strips, fluorescent probes, and artificial intelligence) has accelerated the practical application of biosensors for the detection of ATP-related compounds.

Mechanisms of polyphenols on quality control of aquatic products in storage: A review.

Aquatic products are easily spoiled during storage due to oxidation, endogenous enzymes, and bacteria. At the same time, compared with synthetic antioxidants, based on the antibacterial and antioxidant mechanism of biological agents, the development of natural, nontoxic, low-temperature, better-effect green biological preservatives is more acceptable to consumers. The type and molecular structure of polyphenols affect their antioxidant and antibacterial effectiveness. This review will describe how they achieve their antioxidant and antibacterial effects. And the recent literature on the mechanism and application of polyphenols in the preservation of aquatic products was updated and summarized. The conclusion is that in aquatic products, polyphenols alleviate lipid oxidation, protein degradation and inhibit the growth and reproduction of microorganisms, so as to achieve the effect of storage quality control. And put forward suggestions on the application of the research results in aquatic products. We hope to provide theoretical support for better exploration of the application of polyphenols and aquatic product storage.

Development and validation of a sensitive ultra-high-performance liquid chromatography-tandem mass spectrometry method for quantitative analysis of bambermycin in livestock and aquatic products: Implications for food safety control and regulatory enforcement.

A sensitive and accurate analytical method was developed and validated to detect bambermycin, a commonly used antibiotic in animal feed and livestock. The presence of bambermycin residues in food products can pose health risks to consumers, emphasizing the need for a sensitive and accurate analytical method. A reversed-phase analytical column was utilized with a mobile phase comprising 0.005 mol/L ammonium acetate in 5% acetonitrile (A) and 0.005 mol/L ammonium acetate in 95% acetonitrile (B) to achieve effective chromatographic separation. Quantitative determination of bambermycin in various samples, including beef, pork, chicken, milk, eggs, flatfish, eel, and shrimp, was performed using ultra-high-performance liquid chromatography-tandem mass spectrometry. Sample extraction involved a mixture of methanol and a 25% ammonium hydroxide solution, followed by low-temperature purification and phospholipid removal utilizing a Phree cartridge. The method exhibited a satisfactory recovery rate ranging from 69% to 100%. Validation results demonstrated the reliability, robustness, and accuracy of the method, exhibiting good linearity, precision, and recovery. This validated method can be applied for routine analysis of bambermycin residues, assisting in the development of effective monitoring and control measures to ensure the safety of livestock and aquatic products.

Residue analysis of 10 aminoglycoside antibiotics in aquatic products by multiwalled carbon nanotubes combined with mixed-mode ion exchange liquid chromatography-tandem mass spectrometry.

An ultra-high-performance liquid chromatography-tandem mass spectrometry method was developed for simultaneous determination of 10 kinds of aminoglycosides in edible parts of aquatic products. The samples were extracted with 10 mmol/L potassium dihydrogen phosphate buffer solution, then the pH value of the extract was adjusted to neutral by sodium hydroxide. Half volume of the extract was loaded onto multiwalled carbon nanotubes cartridge. All the target compounds were separated on a mixed-mode ion exchange column and detected by ultra-high-performance liquid chromatography-tandem mass spectrometry with electrospray in the positive ionization mode. Under optimized conditions, this method had a good linearity with a squared correlation coefficient > 0.999. For neomycin, the limit of detection and limit of quantification were 5.0 µg/kg and 10.0 µg/kg, respectively; for hygromycin B and apramycin, values were 2.0 µg/kg and 5.0 µg/kg, respectively; for the other seven kinds of aminoglycosides, values were 1.0 µg/kg and 2.0 µg/kg, respectively. The average recoveries presented 75.8%-107.2% with intra- and interday reproducibility ranging between 3.8% and 12.5%. The method was rapid with good separation and sharp peak shapes, had the characteristicsis of high accuracy and good precision, and was suitable for simultaneous determination of 10 kinds of aminoglycosides in aquatic products.

Observation on the ice crystal formation process of large yellow croaker (Pseudosciaena crocea) and the effect of multiple cryoprotectants pre-soaking treatments on frozen quality.

By observing the formation behavior of ice crystals, the quality of food products under different freezing conditions can be intuitively judged. In this paper, large yellow croaker was taken as the research object, and a novel cryomicroscopic system was developed to directly observe the structure of ice crystals during the freezing process. The cryoprotective effects of 4% sucrose +4% sorbitol (SU + SO), 4% xylo-oligosaccharide (XO), 4% xylo-oligosaccharide + 0.3% tetrasodium pyrophosphate (XO + TSPP) and 0.2% antifreeze protein (AFP) at different freezing temperatures were investigated. And the evaluation indicators, such as cell deformation degree, equivalent diameters, roundness, elongation and fractal dimension were introduced to quantify the damage of ice crystals to muscle tissues and fibers. The results indicate that reducing the freezing temperature and adding cryoprotectants can improve the quality of large yellow croaker. AFP has the best cryoprotective effect, with a reduction in cell deformation degree of 54.78% and 67.83% compared to the Control group at -5 °C and -20 °C, respectively. SU + SO and XO have the equivalent antifreeze effect, which is slightly inferior to XO + TSPP. In addition, physical parameters of large yellow croaker samples were measured to verify the influence of ice crystal structure on product quality. Therefore, direct observation of the ice crystal formation process and evaluation of ice crystal structure can accurately reflect the quality of frozen products, which is of great significance for the development of refrigeration and preservation technology.

Rapid Limit Test of Eight Quinolone Residues in Food Based on TLC-SERS, a New Limit Test Method.

Residual quinolones in food that exceed their maximum residue limit (MRL) are harmful to human health. However, the existing methods used for testing these residues have limitations; so, we developed a new limit test method called TLC-SERS to rapidly determine the levels of residues of the following: enrofloxacin (A), ciprofloxacin (B), ofloxacin (C), fleroxacin (D), sparfloxacin (E), enoxacin (F), gatifloxacin (G), and nadifloxacin (H). The residues ware preliminarily separated via TLC. The tested compounds' position on a thin-layer plate were labeled using their relative Rf under 254 nm ultraviolet light, and an appropriate amount of nanometer silver solution was added to the position. The silver on the plate was irradiated with a 532 nm laser to obtain the SERSs of the compounds. The results show significant differences in the SERS of the eight quinolones: the LODs of H, A, D, E, C, G, F, and B were 9.0, 12.6, 8.9, 19.0, 8.0, 8.7, 19.0, and 12.6 ng/mL, respectively; and the RSD was ≤4.9% for the SERS of each quinolone. The limit test results of 20 samples are consistent with those obtained via UPLC-MS/MS. The results indicate that TLC-SERS is a specific, sensitive, stable, and accurate method, providing a new reference for the rapid limit test of harmful residues in foods.

Highly-Selective Analytical Strategy for 90 Pesticides and Metabolites Residues in Fish and Shrimp Samples.

The analysis of pesticide residues in aquatic products is challenging due to low residue levels and the complex matrix interference. In this study, we developed a simple, fast method for the trace analysis of 90 pesticides and metabolites in aquatic products. The analytes covered a wide polarity range with log Kow (log octanol-water partition coefficient) ranging from -1.2 to 6.37. Grass carp (Ctenopharyngodon idellus) and prawn (Penaeus chinensis) samples were chosen to validate the quantification method. The samples were extracted by 0.2% formic-acetonitrile, cleaned by solid-phase extraction (PRiME HLB), and analyzed by high performance liquid chromatography-tandem mass spectrometry. The results showed good linearities for the analytes and were observed in the range of 0.05-50 µg/L. The recoveries of the method were within 50.4-118.6%, with the relative standard deviations being lower than 20%. The limits of quantifications (LOQs) of the method were in the range of 0.05-5.0 µg/kg, which were superior to values compared with other research. The developed method was applied to detect pesticide residues in prawn samples from eastern coastal areas of China. Three herbicide residues of diuron, prometryn, and atrazine were detected in prawn samples. The method was sensitive and efficient, which is of significance in expanding the screening scope and improving the quantitative analysis efficiency in aquatic products.

One Pot Synthesis of Nanofiber-Coated Magnetic Composites as Magnetic Dispersive Solid-Phase Extraction Adsorbents for Rapid Determination of Tetracyclines in Aquatic Food Products.

A magnetic adsorbent based on a C-nanofiber (Fe3O4@C-NFs) nanocomposite was synthesized using a simple one-pot co-precipitation method. The characterized results showed that the obtained C-nanofiber-coated magnetic nanoparticles had many attractive features such as a large specific surface area and a highly interwoven and branched mesoporous structure, as well as distinguished magnetism. The nanocomposite was then used as an adsorbent in the magnetic solid phase extraction (MSPE) of four typical tetracyclines (oxytetracycline, tetracycline, chlortetracycline, and doxycycline) in aquatic products. The TCs in the extract were determined using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Experimental variables of MSPE, including the sorbent amount, pH condition, adsorption and desorption time, and desorption solvent, were investigated and optimized systematically. The method validation indicated that the developed method showed good linearity (R2 > 0.995) in the range of 1.0-200 ng/mL. The average recoveries at the spiked levels ranged from 90.7% to 102.7% with intra-day and inter-day relative standard deviations (RSDs, n = 6) ranging from 3.72% to 8.17% and 4.20% to 9.69%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) for the four kinds of TCs were 0.7 µg/kg and 2.0 µg/kg, respectively. Finally, MSPE based on C-nanofiber-coated magnetic nanoparticles was successfully applied to TC analysis in real aquatic products (grass carp, large yellow croaker, snakehead, mandarin fish, Penaeus vannamei, swimming crab, etc.). Compared with traditional extraction methods, the proposed method for TC analysis in aquatic products is more sensitive, effective, recyclable, and environmentally friendly.

Engineered nanomaterials-based sensing systems for assessing the freshness of meat and aquatic products: A state-of-the-art review.

Meat and aquatic products are susceptible to spoilage during distribution, transportation, and storage, increasing the urgency of freshness evaluation. Engineered nanomaterials (ENMs) typically with the diameter in the range of 1-100 nm exhibit fascinating physicochemical properties. ENMs-based sensing systems have received extensive attention for food freshness assessment due to the advantages of being fast, simple, and sensitive. This review focuses on summarizing the recent application of ENMs-based sensing systems for food freshness detection. First, chemical indicators related to the freshness of meat and aquatic products are described. Then, how to apply the ENMs including noble metal nanomaterials, metal oxide nanomaterials, carbon nanomaterials, and metal-organic frameworks for the construction of different sensing systems were described. Besides, the recent advance in ENMs-based colorimetric, fluorescent, electrochemical, and surface-enhanced Raman spectroscopy sensing systems for assessing the freshness of meat and aquatic products were outlined. Finally, the challenges and future research perspectives for the application of ENMs-based sensing systems were discussed. The ENMs-based sensing systems have been demonstrated as effective tools for freshness evaluation. The sensing performance of ENMs employed in different sensing systems depends on their composition, size, shape, and stability of nanoparticles. For the real application of ENMs in food industries, the risks and regulatory issues associated with nanomaterials need to be further considered. With the continuous development of nanomaterials and sensing devices, the ENMs-based sensors are expected to be applied in-field for rapid detection of the freshness of meat and aquatic products in the future.

Visual LAMP method for the detection of Vibrio vulnificus in aquatic products and environmental water.

BACKGROUND: A visual, rapid, simple method was developed based on a loop-mediated isothermal amplification (LAMP) assay to detect Vibrio vulnificus in aquatic products and aquaculture waters. RESULTS: Genomic DNA was extracted from Vibrio vulnificus using the boiling method, and optimized primers were used to detect the gyrB gene using a visual LAMP method. The sensitivity of the assay was 10 fg/µL, and the obtained results were stable and reliable. Out of 655 aquatic product samples and 558 aquaculture water samples, the positive rates of Vibrio vulnificus detection were 9.01% and 8.60%, respectively, which are markedly higher than those of the traditional culture identification methods. CONCLUSION: The relatively simple technical requirements, low equipment cost, and rapid detection make the visual LAMP method for the detection of Vibrio vulnificus a convenient choice for field detection in the aquaculture industry.

Shelf life extension of aquatic products by applying nanotechnology: a review.

Aquatic products are extremely perishable due to their biological composition. Conventional preservation methods such as freezing, chemical treatments, packaging, and so forth are unable to inhibit enzymatic and microbiological spoilage efficiently and/or energy intensive and/or potentially toxic. However, the demand of consumers for aquatic products with long shelf life and high quality has urged the food industries to pursuit highly effective preservation methods for shelf life extension of aquatic products. Nanotechnology-related shelf life prolongation process possess the ability to overcome the drawbacks of conventional preservation technologies due to its unique properties. In this article, the aquatic products spoilage mechanisms, recent application of nanotechnology-related preservation techniques for aquatic products as well as the risk and regulation of nanomaterials have been reviewed. It has been shown that nanotechnology-related preservation techniques can effectively extend the shelf life without impairing the quality of aquatic products. However, the safety of nanotechnology is still remained controversial, therefore, the application of nanotechnology should be considered cautiously.

Recent advances on characterization of protein oxidation in aquatic products: A comprehensive review.

In addition to microbial spoilage and lipid peroxidation, protein oxidation is increasingly recognized as a major cause for quality deterioration of muscle-based foods. Although protein oxidation in muscle-based foods has attracted tremendous interest in the past decade, specific oxidative pathways and underlying mechanisms of protein oxidation in aquatic products remain largely unexplored. The present review covers the aspects of the origin and site-specific nature of protein oxidation, progress on the characterization of protein oxidation, oxidized proteins in aquatic products, and impact of protein oxidation on protein functionalities. Compared to meat protein oxidation, aquatic proteins demonstrate a less extent of oxidation on aromatic amino acids and are more susceptible to be indirectly oxidized by lipid peroxidation products. Different from traditional measurement of protein carbonyls and thiols, proteomics-based strategy better characterizes the targeted oxidation sites within proteins. The future trends using more robust and accurate targeted proteomics, such as parallel reaction monitoring strategy, to characterize protein oxidation in aquatic products are also given.

Prevalence of Laribacter hongkongensis in food and environmental matrices: A systematic review and meta-analysis.

Laribacter hongkongensis is a human pathogen harboured in food and environmental matrices. This present study aimed to meta-analysed the prevalence of L. hongkongensis in humans, aquatic products, food/non-food animals, and environmental waters to provide update information on the pathogen. Nine electronic databases were systematically searched for articles on L. hongkongensis and a random-effects-model meta-analysis on its prevalence was conducted. Assessment of heterogeneities and publication biases across the studies was determined by using the I2 statistic and Egger's regression/rank correlation tests of funnel plot, respectively. Furthermore, a meta-regression model was explored to unravel factors influencing the prevalence. A total of 39 documents were identified, of which, 33 articles were included as 98 sub-studies for the meta-analysis, and 87 sub-studies for subgroup-analysis. Overall, the prevalence of L. hongkongesis in human, aquatic products, food/non-food animals, and environmental waters was 8.5% (95% CI: 5.8-11.7). The leave-one-out influence analysis yielded a pooled prevalence of L. hongkongensis ranging from 8.1% (95% CI: 5.4-11.3) - 8.8% (95% CI: 5.8-12.3). Sub-group analysis found that the prevalence of L. hongkongensis was highest in Amphibian (54.6%, 95% CI: 41.3-67.6), followed by Pisces (7.9%, 95% CI: 5.3-10.9), Avian (0.5%, 95% CI: 0-5.8), and Mammal (0.5%, 95% CI: 0-3.6). In addition, Egger's regression-test of funnel plot suggests presence of publication (z = 4.2, p < 0.0001) in mammal subgroup. Multivariate meta-regression showed that the prevalence was significantly influenced by source type, class, and identification/detection method with the source type, class, and detection method specifically accounted for 25.49%, 11.28%, and 3.84% of the heterogeneity, respectively. Conclusively, the prevalence of L. hongkongensis decrease in order of Amphibian (54.6%), Pisces (7.9%), Avian (0.5%) and Mammal (0.5%). Aquatic products and environments are essential sources of the pathogen.

Magnetic polymer particles as a highly efficient and facile cleanup adsorbent for multi-pesticide residues analysis in aquatic products.

A novel and efficient sample pretreatment procedure using magnetic particles was exploited for the determination of multi-pesticide residues in aquatic products. The magnetic adsorbent was prepared using divinyl benzene and N-vinyl pyrrolidone as functional monomers modified on the Fe3O4 @SiO2. The obtained magnetic adsorbent, octadecylsilane sorbents, and graphitized carbon black were employed as effective adsorbents to remove matrix interferences in aquatic products, and their dosages were optimized. Satisfactory levels of accuracy and precision were procured under optimum conditions. The method limits of quantification ranged from 0.1 to 2.0 µg/kg. The analytical accuracy of the developed method for the analysis of multi-pesticide residues in freshwater and seafood products was validated. It was found to be suitable for the analysis of multi-pesticide residues in different types of aquatic products. Additionally, the method was successfully applied for the analysis of pesticide residues in fish samples obtained from aquaculture plants located in Zhejiang Province, China. The detected concentrations of pesticides ranged from 0.14 to 0.95 µg/kg. In general, this method shows promising application prospects for the rapid determination of multi-pesticide residues in aquatic products.

Highly sensitive SERS detection of residual nitrofurantoin and 1-amino-hydantoin in aquatic products and feeds.

Nitrofurantoin (NFT), a typical highly effective nitrofuran antibiotic drug, has been prohibited but still widely found in animal food products. It can be metabolized in animals to form 1-amino-hydantoin (AHD) that can then form stable and toxic metabolite-protein adducts. Hence, the detection of NFT and AHD in aquatic products and feeds is very important. However, there are limited reports concerning NFT detection and none about AHD by using surface-enhanced Raman spectroscopy (SERS) method. Herein, potassium bromide (KBr) decorated silver (Ag) nanoparticles (Ag-BrNPs)-based SERS approach was proposed for NFT and AHD detection. The limit of detection (LOD) for NFT was 1 µg/L. The detection of NFT residues in sea cucumber and fish feeds was also realized with the LOD of 1 and 50 ng/g, respectively. More importantly, the sensing of AHD was easily realized with the SERS approach for the first time. After the derivatization with 2-nitrobenzaldehyde (2-NBA), Ag-BrNPs were also successfully utilized for AHD detection in sea cucumber with the LOD of 5 ng/g.

Advanced materials on sample preparation for safety analysis of aquatic products.

Safety analysis of aquatic products has been a challenge in recent years due to the serious matrix interference, complex characteristics, and ultra-low content of analytes. Introducing advanced materials to sample preparation technique can greatly improve the extraction, enrichment, and separation for further qualification and quantification of target analytes by coupling with consequent analytical technologies. Based on this scope, this review is mainly introducing advanced materials on the sample preparation for safety analysis of aquatic products in the past decade. After introducing the importance of the corresponding advanced materials, advanced materials are used for the sample preparation and in the improvement of safety analysis result of aquatic products. Advanced materials for sample preparation of aquatic products were reviewed including carbon materials, metal organic frameworks, covalent organic frameworks, molecularly/ions imprinted polymers, etc. Then, applications of the advanced materials for the analysis of specific fishery analytes (antibiotics, anesthetic, preservatives, etc.) were briefly introduced. Conclusions and perspectives on advanced materials for sample preparation and safety analysis of aquatic products were also presented.

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.