Seafood Samples Research Articles

Phenotypic and genotypic characterization of pathogenic Escherichia coli identified in resistance mapping of β-lactam drug-resistant isolates from seafood along Tuticorin coast.

The ubiquity of pathogenic E. coli isolate possessing antimicrobial resistance was investigated in seafood samples procured from major seafood supply chain markets established for export and domestic consumption along Tuticorin coast. Out of 63 seafood samples examined, 29 (46%) were found to be contaminated by pathogenic E. coli harbouring one or more genes of virulent potential. Based on virulome profiling, 9.55% of isolates belonged to enterotoxigenic E. coli (ETEC), 8.08% to enteroaggregative E. coli (EAEC), 7.35% to enterohemorrhagic E. coli (EHEC), 2.20% to enteropathogenic E. coli (EPEC), and 2.20% to uropathogenic E. coli (UPEC). All the 34 virulome positive and haemolytic pathogenic E. coli have been serogrouped as O119, O76, O18, O134, O149, O120, O114, O25, O55, O127, O6, O78, O83, O17 and clinically significant O111, O121, O84, O26, O103, and O104 (non-O157 STEC) serotypes in this study. Multi-drug resistance (MDR) (≥ 3 antibiotic classes/sub-classes) was exhibited in 38.23% of the pathogenic E. coli, and 17.64% were extensive drug resistant (XDR). Extended spectrum of β-lactamase (ESBL) genotypes were confirmed in 32.35% isolates and 20.63% isolates harboured ampC gene. One sample (Penaeus semisulcatus) collected from landing centre (L1) harboured all ESBL genotypes blaCTX-M, blaSHV, blaTEM, and ampC genes. Hierarchical clustering of isolates revealed the separation of ESBL isolates into three clusters and non-ESBL isolates into three clusters based on phenotypic and genotypic variations. Based on dendrogram analysis on antibiotic efficacy pattern, carbapenems and β-lactam inhibitor drugs are the best available treatment for ESBL and non-ESBL infections. This study emphasizes the significance of comprehensive surveillance of pathogenic E. coli serogroups that pose serious threat to public health and compliance of AMR antimicrobial resistant genes in seafood that hinder seafood supply chain.

Biodistribution of 210Po in seafood and risk assessment for consumers in Sweden

Seafood consumption per capita, in Sweden, is larger than World and European average. Although, 36% of Swedes consume seafood meals at least two times per week, the Swedish National Food Agency advises the necessity to increase this ratio. Seafood is one of the main entrances of 210Po in the human food chain. Due to the high radiotoxicity, the intake of 210Po plays an important role in the human health, even in extremely small quantities. In this study, 114 seafood samples representing 52 different marine species were analyzed. The biodistribution of 210Po in seafood species were not uniformly distributed being higher in digestive system and gonads, and lower in seafood muscle. The activity concentration of 210Po in fish ranged between 0.01 and 26 Bq/kg with an average value of 4 Bq/kg, whereas in shellfish fluctuated between 0.1 and 239 Bq/kg, with a mean concentration of 18 Bq/kg. In general, the activity concentration of 210Po in processed products were lower than fresh samples due to the decay of 210Po from seafood capture to purchase. However, in boiled seafood such as Norway Lobster, with short elapsed time from collection to purchase, the boil samples presented higher activity concentration of 210Po than fresh products. The results of the study showed that the annual intake of 210Po via seafood consumption in Sweden exponentially increased by age and it was slightly higher in males than females. As a result, the annual committed dose ranged from 60 to 154 μSv, with an average value of 103 ± 31 μSv, being controlled by fish consumption below 14 years old and by seafood consumption above 14 years old. Finally, the committed effective dose could increase up to 479 μSv/y for population group with higher seafood consumption.

Toxic Metal Concentrations and Exposure Risks Associated with Surface Water, Seafood (Clarias gariepinus, Oreochromis niloticus, Cottus gobio) and Vegetable (Telfairia occidentalis) from Elebele River, Nigeria

Human exposure to elevated levels of environmental contaminants is an important concern of health toxicology. This study assessed the toxicity level of toxic metals including Arsenic (As), Cadmium (Cd), Chromium (Cr), Copper (Cu), Lead (Pb) and Nickel (Ni) in samples of water, seafood (Clarias gariepinus, Oreochromis niloticus, Cottus gobio) and vegetable (Telfairia occidentalis) from the adjacent area of Elebele River, Nigeria, bioconcentration and toxic metal exposure posed to communities consuming these foodstuffs. The following indices: single-factor index and the comprehensive pollution index, metal pollution index, estimated daily and weekly intakes, hazard index and lifetime cancer risk were applied. Samples of water, seafood and vegetable were analysed using Atomic Absorption Spectrophotometer. The results showed that the concentrations of metals except for Cd in water samples were higher than the permissible limits by international organisations. Results also revealed that the concentrations of metals in foodstuff samples were within limits. Furthermore, the values of estimated weekly intakes calculated were lower than the limits of provisional tolerable weekly intakes established by the Food and Agriculture Organization and World Health Organization. This suggests no health risks and is consistent with the HI results. However, As was a major contributor (96.9%) to health risks associated with the ingestion of water. Lifelong consumption of T. occidentalis might be hazardous in the study locality. The carcinogenic risk was > 1 × 10‒4 for As and Ni. Therefore, to reduce the health risk and the extent of metal contamination, steps must be taken for the efficient removal of metals from the water body.

Comparative genomic analysis reveals the potential transmission of Vibrio parahaemolyticus from freshwater food to humans

Vibrio parahaemolyticus is an increasingly important foodborne pathogen that cause acute gastroenteritis in humans. However, the prevalence and transmission of this pathogen in freshwater food remains unclear. This study aimed to determine the molecular characteristics and genetic relatedness of V. parahaemolyticus isolates obtained from freshwater food, seafood, environmental, and clinical samples. A total of 138 (46.6%) isolates were detected from 296 food and environmental samples, and 68 clinical isolates from patients. Notably, V. parahaemolyticus was more prevalent in freshwater food (56.7%, 85/150) than in seafood (38.8%, 49/137). Virulence phenotype analyses revealed that the high motility of isolates from freshwater food (40.0%) and clinical isolates (42.0%) was higher than that of isolates from seafood (12.2%), whereas the biofilm-forming capacity of freshwater food isolates (9.4%) was lower than that of seafood (22.4%) and clinical isolates (15.9%). Virulence genes analysis showed that 46.4% of the clinical isolates contained the tdh gene encoding thermostable direct hemolysin (TDH) and only two freshwater food isolates contained the trh gene encoding TDH-related hemolysin (TRH). Multilocus sequence typing (MLST) analysis divided the 206 isolates into 105 sequence types (STs), including 56 (53.3%) novel STs. ST2583, ST469, and ST453 have been isolated from freshwater food and clinical samples. Whole-genome sequence (WGS) analyses revealed that the 206 isolates were divided into five clusters. Cluster II contained isolates from freshwater food and clinical samples, whereas the other clusters contained isolates from seafood, freshwater food, and clinical samples. In addition, we observed that ST2516 had the same virulence pattern, with a close phylogenetic relationship to ST3. The increased prevalence and adaption of V. parahaemolyticus in freshwater food is a potential cause of clinical cases closely related to the consumption of V. parahaemolyticus contaminated freshwater food.

Evaluation of DNA metabarcoding using Oxford Nanopore sequencing for authentication of mixed seafood products

Seafood is the world's most highly traded food commodity. Due to the non-stop demand of the ever-increasing human population, the supply of certain species is not guaranteed, and mislabelling practices arise. Fillets and heavily processed products that cannot be easily authenticated are particularly vulnerable to fraudulent practices. In order to face this challenge, as a cost-effective, rapid, and easy handling tool, the MinION sequencer from Oxford Nanopore Technologies (ONT) coupled with DNA (meta)barcoding represents a suitable option to assess seafood fraud. In this study, we evaluated the feasibility of MinION sequencing to authenticate mixed seafood products by (1) evaluating MinION generated barcodes from single species that have already been Sanger sequenced and (2) performing MinION sequencing of mixed samples containing commercial seafood species in different amounts to evaluate whether all species can be detected, even when they are low abundant. Using the mitochondrial DNA gene markers Cytb and COI, 86% and 76% of the single species were correctly identified, respectively, of which 26% and 29% also showed non-target species. For the mixed samples, not all species were detected regardless of the composition of the mixtures or the marker gene used. Nevertheless, the MinION sequencing platform can be considered an additional tool to complement currently available approaches to authenticate mixed seafood samples providing that adequate measures are taken to reduce false positives and false negatives. • ONT-based metabarcoding detects 76% (COI) and 86% (Cytb) of tested seafood species. • The detection of non-target species impact interpretation of DNA metabarcoding data. • Multiple marker genes increase the detection of fish species with DNA metabarcoding.

A new aggregation-induced emission-based fluorescent probe for effective detection of Hg2+ and its multiple applications

Detection of mercury ions (Hg2+) in actual samples is of significant importance due to the toxicity of Hg2+ to human health. In this work, a simple tetraphenylethene (TPE) derived fluorescent probe TPE-Hg based on aggregation-induced emission (AIE) mechanism was synthesized. TPE-Hg can visually recognize Hg2+ in THF/HEPES (1:9, v/v, HEPES 20 mmol/L, pH 7.3) system with rapid response, strong anti-interference ability, large Stokes shift (203 nm), and low detection limit (7.548 × 10−7 mol/L). The results show that Hg2+ triggered elimination of TPE-Hg lead to releasing of an AIE-active compound 2 is responsible to the sensing mechanism. TPE-Hg is applicable to detect Hg2+ in actual water samples and image Hg2+ in living MCF-7 cells. In addition, TPE-Hg is suitable to assay the Hg2+ level in seafood and tea samples, and it is also applicable in test strips.

Incidence, virulence genes and antimicrobial resistance of Vibrio parahaemolyticus isolated from seafood

The objective of the study was to establish the incidence, pathogenic factors and antimicrobial resistance of Vibrio parahaemolyticus in seafood from retail shops in Bulgaria. A hundred and eighty samples of sea fish, mussels, oysters, veined rapa whelks, shrimps and squids were included in the study. PCR methods were used to identify V. parahaemolyticus and prove tdh and trh genes. Antimicrobial resistance was established by disc diffusion method, and MAR index was calculated. The results proved the presence of V. parahaemolyticus in 24% (44/180) of the seafood samples. tdh-positive V. parahaemolyticus was not found, while the trh gene was detected in one veined rapa whelk isolate. All isolates were susceptible to Sulfamethoxazole/trimethoprim, Tetracycline, Gentamycin, Amoxicillin-clavulanic acid, Amikacin, Ciprofloxacin, and Levofloxacin. Intermediate resistance was found to Ampicillin (25%; 11/44), Cefepime (16%; 7/44), and Ceftazidime (2%; 1/44). The results showed that 16% (7/44) of the isolates were resistant to Cefepime, 9% (4/44) to Ampicillin, and 5% (2/44) to Ceftazidime. MAR-index values ranged from 0.10 to 0.30. The incidence of pathogenic and multidrug-resistant V. parahaemolyticus strains in seafood offered on the market poses a risk to consumer health.

Secondary Validation of a Liquid Scintillation Counter-method for Residues of Tetracyclines, Beta-lactams, and Sulfonamides in Seafood/Aquaculture Products

This study was carried out to validate the liquid scintillation counter method (Charm II) for the detection of tetracyclines, beta-lactams, and sulfonamides (Sulfa drugs) in a range of Aquaculture Products. This method of validation followed primary validation performed in Belgium and was therefore transferred to Nigeria but further validation was required, and this was performed according to the European Commission Decision 2002/657/EC. Method performance was based on the detection capability (CCβ), specificity (cross-reactivity), robustness, repeatability, and reproducibility for the detection of antimicrobial residues. Seafood and aquaculture samples used for the validation process included tilapia (Oreochromis niloctus), catfish (Siluriformes), African threadfin (Galeoides decadactylus), common carp (Cyprinus carpio), and shrimps (penaeidae). These were spiked with varying concentrations of tetracyclines, beta-lactams, and sulfonamides standards to determine the validation parameters. Results of the validation showed tetracyclines had detection capabilities of 50 µg/kg, while beta-lactams and sulphonamides had detection capabilities of 25 µg/kg. The relative standard deviation for both repeatability and reproducibility studies ranged between 1.36% and 10.50%. Results of this study are suitable and comparable to the initial validation reports from the primary validation ofCharm II tests forthedetection ofantimicrobial residues inarange ofaquaculture fish conducted in Belgium. The results also prove the specificity, ruggedness, and reliability of the radio receptor assay tests for detection of the various antimicrobials in aquaculture products. This could be used in seafood/aquaculture products monitoring in Nigeria.

Piperazine-linked metal covalent organic framework-coated fibers for efficient electro-enhanced solid-phase microextraction of chlorophenols

Conductive covalent organic frameworks (COFs) have received considerable attention and are critical in various applications such as electro-enhanced solid-phase microextraction (EE-SPME). In this work, a novel piperazine-linked copper-doped phthalocyanine metal covalent organic framework (CuPc-MCOF) was synthesized with good stability and high electrical conductivity. The synthesized CuPc-MCOF was then used as an EE-SPME coating material for extraction of five trace chlorophenols (CPs), including 2,4-dichlorophenol (2,4-DCP), 2,6-dichlorophenol (2,6-DCP), 2,4,6-trichlorophenol (2,4,6-TCP), 2,4,5-trichlorophenol (2,4,5-TCP) and 2,4,5,6-tetrachlorophenol (2,4,5,6-TCP), exhibiting excellent extraction performance because of various synergistic forces between CuPc-MCOF fibers and CPs. By combining EE-SPME with gas chromatography-tandem mass spectrometry (GC–MS/MS), a sensitive method for CPs detection was established with a low limit of detection (0.8–5 ng L−1) and good reproducibility (RSD≤8.4%, n = 3). This method was then successfully applied to the analysis of trace CPs in real samples of seawater and seafood. Results showed that the developed CuPc-MCOF coating material possessed superior extraction performance and potential application in extraction of trace polar pollutants from complex samples.

Determination of benzothiazoles, benzotriazoles and benzenesulfonamides in seafood using quick, easy, cheap, effective, rugged and safe extraction followed by gas chromatography - tandem mass spectrometry: Method development and risk assessment

The common use of benzothiazoles, benzotriazoles and benzenesulfonamides has led to widespread ubiquity in several environmental matrices. Their occurrence in edible fish could represent an additional exposure route for the population. The present study aims to develop a method for the simultaneous determination of these three compound families in seafood samples. Based on QuEChERS extraction, different salt combinations and clean-up strategies have been evaluated to achieve the highest recoveries while reducing the matrix effect in low and high lipidic content species. The best results were obtained with the original method salts and the lipid-selective push-through clean-up, which combined with gas chromatography-tandem mass spectrometry led to recoveries between 50 and 112% with negligible matrix effects and method detection limits between 0.15–9.50 ng g−1 dw. The application of the method to commercially available samples confirmed the presence of BTs as well as BSAs, with the latter being determined in seafood for the first time. Exposure and risk assessment calculations indicated a minor risk for the population when consuming fish.

Optimization of sample preparation conditions in the determination of total arsenic in fish and seafoods by atomic absorption spectrometry with electrothermal atomization

The conditions for sample preparation and determination of total arsenic in fish and seafoods by atomic absorption spectroscopy with electrothermal atomization have been optimized. When using a standard sample preparation procedure (GOST R 53100), a complete decomposition of the organic arsenic compound, arsenobetaine, appeared impossible which leads to underestimated results. A novel sample preparation procedure for the determination of total arsenic, including the addition of concentrated sulfuric acid for complete decomposition of the organic forms of arsenic to inorganic ones is proposed. During the atomization of the sample, an additional stage of drying was introduced with smooth heating from 200 to 250°C, which contributed to a complete removal of sulfuric acid residues from the injected sample volume. The correctness of the proposed methodology was verified using the ICP-MS method and in the analysis of reference samples of fish and seafoods.

Antibiogram, Genomic and Phylogeny of Stool and Seafood Isolates from Some Cholera-Prone Coastal Communities in Rivers State, Nigeria

Cholera is a significant public health threat across the globe, especially in coastal regions with poor water supply. This study was carried out to determine the antibiogram, genomic, and phylogeny of stool and seafood isolates from some cholera-prone coastal communities in Rivers State, Nigeria. A total of 400 stool samples and 42 different seafood were aseptically collected and examined using standard microbiology and molecular techniques. An antibiogram of isolates from seafood and stool samples was assayed. Genes for virulence, resistance, and relatedness of bacteria identified were also determined. The isolates from the stool and seafood were examined for susceptibility to some selected antibiotics. The findings showed the prevalence rate of cholera in the communities as follows: 16% in Kaa, 30% in Andoni, 4% in Ogu/Bolo, and 10% in Abua/Odual. The isolates from stool were susceptible to Ciprofloxacin and Gentamycin with a susceptibility rate of 94.12% each while 100% resistance was recorded against Amoxicillin-clavulanic acid, 94.12% against Amikacin and 88.24% against Colistin. For the sea foods, the isolates were susceptible to gentamycin and ciprofloxacin with a susceptibility rate of 91.43% and 82.86% respectively. Resistance was also recorded against Colistin (88.57%) and Azithromycin (82.86%). Testing the isolates for the presence of 16SrRNA genes showed that all were positive with 1500 bp 16SrRNA gene band size. TEM, OXA, SHV, and CTX-M resistant genes were detected whereas the virulence genes were TDH and AcrB. The phylogenetic analysis revealed isolates from seafood to be Aeromonas dhakensis, Vibrio parahaemolyticus, Vibrio azureus, and Providencia rettgeri, while in stool samples they were Enterobacter sichuanensis, Enterobacter hormaechei, Providencia sneebia, and Proteus vulgaris. Providencia stuartii, Proteus mirabilis, Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae were common isolates from both seafood and stool samples. This study has shown that not all reported cases of cholera are caused by Vibrio cholerae. Therefore, attention should be paid to other water-borne bacteria in every outbreak, especially in coastal communities.

An “AIE + ESIPT” mechanism-based benzothiazole-derived fluorescent probe for the detection of Hg2+and its applications

A simple “AIE + ESIPT” mechanism-based fluorescent probe for Hg2+detection has been developed. The probe is applicable to detect Hg2+in living cells, natural water, and seafood samples.

The emergence of Methicillin-resistant Staphylococcus aureus in seafood samples and possible control measures

The emergence of Methicillin-resistant Staphylococcus aureus in seafood samples and possible control measures

Antimicrobial Resistant Bacteria Monitoring in Raw Seafood Retailed: a Pilot Study Focused on Vibrio and Aeromonas.

In aquaculture, bacterial infections in sea animals are treated using antimicrobials. As seafood is frequently consumed in its raw form, seafood contaminated with water-borne antimicrobial-resistant bacteria presents a potential transmission route to humans and can influence food safety. In this study, we aimed to determine the abundance of water-borne bacteria in retail raw seafood and to characterize their antimicrobial resistance profiles. In total, 85 retail raw seafood samples (32 fish, 26 shellfish, 25 mollusks, and two crustaceans) were purchased from supermarkets in Japan, and water-borne bacteria were isolated. The isolated bacterial species predominantly included Vibrio spp. (54.1%) and Aeromonas spp. (34.1%). Vibrio or Aeromonas spp. were isolated from more than 70% of the seafood samples. Tetracycline-, sulfamethoxazole-, and/or trimethoprim/sulfamethoxazole-resistant Vibrio or Aeromonas spp. isolates were detected in seven (21.9%) fish samples (two wild-caught and five farm-raised) harboring tet, sul, and/or dfr genes. Sulfamethoxazole- and trimethoprim/sulfamethoxazole-resistant isolates were only detected in farm-raised fish. Tetracycline and sulfamethoxazole are commonly used in aquaculture. These results suggest that water-borne bacteria like Vibrio and Aeromonas spp. should be the primary focus of antimicrobial-resistant bacteria monitoring to effectively elucidate their spread of bacteria via seafood.

Detection of Escherichia fergusonii - an emerging pathogen harbouring drug resistant genes from seafood samples of Tamil Nadu, India

Detection of Escherichia fergusonii - an emerging pathogen harbouring drug resistant genes from seafood samples of Tamil Nadu, India

Prevalence of Salmonella in Sea Foods and Its Resistance to Drugs

Salmonella are non-spore forming, predominantly motile enterobacteria with peritrichous flagella (all around the cell body). They are intracellular pathogens causing illness. They usually invade only the gastrointestinal tract and cause Salmonellosis. Humans become infected most frequently through contaminated food or water. Sea foods are mostly associated with Salmonella infections. This study therefore was carried out to isolate Salmonella and determine the antibiotic sensitivity patterns of the Salmonella isolates from sea foods associated with food-borne diseases. These sea foods were obtained from three different selected markets within Port Harcourt Metropolis, Rivers State. A total of three (3) sea food samples were collected at random from each of the market. The samples were put through standard microbiological techniques. The result of total heterotrophic bacterial counts showed that Prawn from Mile 1 market had high count of 2.06x108 cfu/g while Crab from Creek Road market had the least count of 1.15x108 cfu/g. The result of total coliform count showed that Crab from Mile 1 market had the highest count of 2.86x106 cfu/g while Periwinkle from Creek Road market had the least count of 2.30x106 cfu/g. Also, the result of salmonella shigella count showed that Periwinkle from Mile 1 market had the least count of 0.76x105 cfu/g while Crab from Creek Road market had the highest count of 2.80x105 cfu/g. Characteristics of bacterial isolates from the sea foods showed that Proteus sp., Bacillus spp., Pseudomonas sp., Micrococcus sp., Staphylococcus aureus, Escherichia coli, and Salmonella spp. were present and identified from the samples. The result of the antibiotic susceptibility pattern of the Salmonella isolates showed that all the isolates were 100% susceptible to Tarivid, Peflacine, Septrine and Ciprofloxacin while they exhibited 100% intermediate sensitivity or resistance to the other antibiotics such as Ceporex, Nalidixic acid, Ampicillin, Gentamycin, Streptomycin, and Augmentin. The result of the multidrug resistance index of 3 (100%) of the 3 Salmonella isolates had a MAR index ≥ 0.2. The presence of these organisms in sea food could pose threat of food-borne infection as well as resistance to some commonly used antibiotics. Enforcement of existing laws associated with food storage, preparation and hygiene should be done in order to prevent or reduce these food-borne diseases such as salmonellosis.

Occurrence and Molecular Characterization of Potentially Pathogenic Vibrio spp. in Seafood Collected in Sicily.

Seafood can vehiculate foodborne illnesses from water to humans. Climate changes, increasing water contamination and coastlines anthropization, favor the global spread of Vibrio spp. and the occurrence of antibiotic-resistant isolates. The aim of this study was to evaluate the spread of potentially pathogenic Vibrio spp. in fishery products collected in Sicily and to assess their antibiotic resistance. Bacteriological and molecular methods were applied to 603 seafood samples to detect V. parahaemolyticus, V. cholerae, V. vulnificus, and Vibrio alginolyticus in order to assess their pathogenicity and antimicrobial resistance. About 30% of bivalves and 20% of other fishery products were contaminated by Vibrio spp.; V. parahaemolyticus accounted for 43/165 isolates, 3 of which were carrying either tdh or trh; V. cholerae accounted for 12/165 isolates, all of them non-O1 non-O139 and none carrying virulence genes; and V. vulnificus accounted for 5/165 isolates. The highest rates of resistance were observed for ampicillin, but we also detected strains resistant to antibiotics currently included among the most efficient against Vibrio spp. In spite of their current low incidence, their rise might pose further issues in treating infections; hence, these results stress the need for a continuous monitoring of antimicrobial resistance among fishery products and an effective risk assessment.

A lanthanide-based high-sensitivity fluorescence method for the on-site rapid detection of thermostable direct hemolysin of Vibrio parahaemolyticus

Vibrio parahaemolyticus is a common foodborne pathogen in seafood, which often causes seafood borne bacterial gastroenteritis or food poisoning. Thermostable direct hemolysin (TDH) is considered to be one of the main virulence factors involved in this pathogen. The most clinical V. parahaemolyticus isolates produce TDH. Therefore, high sensitivity and specificity detection of TDH are of great significance for food safety and early diagnosis of diseases caused by V. parahaemolyticus. In this study, we developed a rapid, sensitive immunochromatographic test paper assay for the quantitative detection of TDH in seafood samples using time-resolved fluorescence techniques. First, we completed the preparation of fluorescent detection antibodies by coupling lanthanide fluorescent nanospheres with homemade high-affinity polyclonal antibodies based on the principle of the double-antibody sandwich. The lanthanide fluorescent nanospheres used in this study are characterized by a large stokes shift and a long fluorescence lifetime, which effectively reduces background noise and improves detection sensitivity. In addition, the method can be completed within 15 min for the detection of TDH, has a detection limit below 50 ng/mL and good linearity in the range of 50–5000 ng/mL. Moreover, it has good specificity and no cross-reactivity with Vibrio vulnificus hemolysin (VVH), Clostridium perfringens α toxin (CPA) or C. perfringens ε toxin (ETX). Finally, the sensitivity of this method was unchanged when the three simulated samples of Patinopecten yessoensis, Ruditapes philippinarum, and Scapharca broughtonii tested, indicating that the method is not affected by samples in a complex matrix. In conclusion, this study establishes a practical new method for on-site rapid detection of TDH, which is easy to operate, fast response, easy to carry and can be implemented under the field conditions without expensive equipment and professional person.

Solid Sampling Pyrolysis Adsorption-Desorption Thermal Conductivity Method for Rapid and Simultaneous Detection of N and S in Seafood.

In this work, a rapid method for the simultaneous determination of N and S in seafood was established based on a solid sampling absorption-desorption system coupled with a thermal conductivity detector. This setup mainly includes a solid sampling system, a gas line unit for controlling high-purity oxygen and helium, a combustion and reduction furnace, a purification column system for moisture, halogen, SO2, and CO2, and a thermal conductivity detector. After two stages of purging with 20 s of He sweeping (250 mL/min), N2 residue in the sample-containing chamber can be reduced to <0.01% to improve the device’s analytical sensitivity and precision. Herein, 100 s of heating at 900 °C was chosen as the optimized decomposition condition. After the generated SO2, H2O, and CO2 were absorbed by the adsorption column in turn, the purification process executed the vaporization of the N-containing analyte, and then N2 was detected by the thermal conductivity cell for the quantification of N. Subsequently, the adsorbed SO2 was released after heating the SO2 adsorption column and then transported to the thermal conductivity cell for the detection and quantification of S. After the instrumental optimization, the linear range was 2.0−100 mg and the correlation coefficient (R) was more than 0.999. The limit of detection (LOD) for N was 0.66 μg and the R was less than 4.0%, while the recovery rate ranged from 95.33 to 102.8%. At the same time, the LOD for S was 2.29 μg and the R was less than 6.0%, while the recovery rate ranged from 92.26 to 105.5%. The method was validated using certified reference materials (CRMs) and the measured N and S concentrations agreed with the certified values. The method indicated good accuracy and precision for the simultaneous detection of N and S in seafood samples. The total time of analysis was less than 6 min without the sample preparation process, fulfilling the fast detection of N and S in seafood. The establishment of this method filled the blank space in the area of the simultaneous and rapid determination of N and S in aquatic product solids. Thus, it provided technical support effectively to the requirements of risk assessment and detection in cases where supervision inspection was time-dependent.