Eel Samples Research Articles

Proximate composition, fatty acid profile and total amino acid contents in samples of the European eel (Anguilla anguilla) of different weights

European eel of different sizes were caught in the River Ulla (Galicia, NW Spain) during winter. The proximate composition differed significantly between fish of different sizes. Discriminant canonical analysis was used to identify the components that enable specimens of different weights to be distinguished. Fat content was the most variable parameter and was directly related to the weight of the fish. The fatty acids that greater increased their content during the growth of the eel were linolenic acid, arachidonic acid, eicosatrienoic acid, and tricosanoic acid. The lipid profiles and quality indices of the eels indicated their high nutritional quality. The threonine, lysine, serine, arginine, alanine and proline contents were highest in the smaller eels. The European eel is a source of high-quality protein with a well-balanced amino acid profile. Moreover, the ratio of essential to non-essential amino acids was highest in the larger eels.

Assessing Temporal Patterns and Species Composition of Glass Eel (Anguilla spp.) Cohorts in Sumatra and Java Using DNA Barcodes

Anguillid eels are widely acknowledged for their ecological and socio-economic value in many countries. Yet, knowledge regarding their biodiversity, distribution and abundance remains superficial—particularly in tropical countries such as Indonesia, where demand for anguillid eels is steadily increasing along with the threat imposed by river infrastructure developments. We investigated the diversity of anguillid eels on the western Indonesian islands of Sumatra and Java using automated molecular classification and genetic species delimitation methods to explore temporal patterns of glass eel cohorts entering inland waters. A total of 278 glass eels were collected from monthly samplings along the west coast of Sumatra and the south coast of Java between March 2017 and February 2018. An automated, DNA-based glass eel identification was performed using a DNA barcode reference library consisting of 64 newly generated DNA barcodes and 117 DNA barcodes retrieved from BOLD for all nine Anguilla species known to occur in Indonesia. Species delimitation methods converged in delineating eight Molecular Operational Taxonomic Units (MOTUs), with A. nebolusa and A. bengalensis being undistinguishable by DNA barcodes. A total of four MOTUs were detected within the glass eel samples, corresponding to Anguilla bicolor, A. interioris, A. marmorata, and A. nebulosa/A. bengalensis. Monthly captures indicated that glass eel recruitment peaks in June, during the onset of the dry season, and that A. bicolor is the most prevalent species. Comparing indices of mitochondrial genetic diversity between yellow/silver eels, originating from several sites across the species range distribution, and glass eels, collected in West Sumatra and Java, indicated a marked difference. Glass eels displayed a much lower diversity than yellow/silver eels. Implications for the management of glass eel fisheries and species conservation are discussed.

Deep eutectic solvents based assay for extraction and determination of zinc in fish and eel samples using FAAS

A new assay based on effective (high recovery) extraction by means of deep eutectic solvents (DESs) was developed for ppb level determination of zinc in fishes and eel samples. Choline chloride and Phenol in a 1:2 M ratio was selected as optimal DES-based extraction solvent. 8-Hydroxy quinoline was used as a chelating agent for zinc ions. The optimized conditions were found at pH value of 8, ligand concentration of 10 mg/L, THF volumetric ratio in bulk solution of 0.5:10. The total time at optimal sample preparation conditions was 5 min for digested sample. Developed method fits to the purpose of routine analysis of fishes and eels. The LOD and LOQ were found 0.041 μg/kg and 0.136 μg/kg with pre-concentration factor of 25 and RSD 1.7%.

Genetic diversity, population structure and demographic history of the tropical eel Anguilla bicolor pacifica in Southeast Asia using mitochondrial DNA control region sequences

The tropical catadromous eel, Anguilla bicolor pacifica, an important fishery resource in Southeast Asia, is under threat due to overexploitation (especially of its glass eel phase) and the limited information on their current genetic status which is necessary for resource management. Mitochondrial DNA (mtDNA) control region sequences, a useful marker for population genetic studies in many aquatic organisms, were used to investigate the genetic diversity, population structure and demographic history of A. bicolor pacifica in the region. A total of 151 specimens were collected from three sites in Southeast Asia, namely: Phu Yen, Vietnam (n = 48); General Santos, Philippines (n = 52); and, Palu, Indonesia (n = 51). A total of 138 haplotypes were identified using the mtDNA control region sequences. In spite of the lack of shared haplotypes, low and non-significant FST values, high haplotype diversity in concurrence with relatively low nucleotide diversity, a haplotype network with no phylogeographic structuring indicate no significant genetic population structuring among the eel samples from Vietnam, Philippines and Indonesia. Population expansion of A. bicolor pacifica was also suggested based on the results of the neutrality tests, mismatch distribution analysis and Bayesian skyline plot. Taken together, a joint management strategy for A. bicolor pacifica must involve countries in Southeast Asia particularly Vietnam, Philippines and Indonesia for its sustainable use.

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The European eel, a catadromous endangered species, displays plasticity in phenotypic traits and in trophic behaviour, features that can eventually affect growth. The aim of this study was to compare variation in carbon (δ13C) and nitrogen (δ15N) stable isotopes in muscle tissue of the adult eel life stages (i.e. yellow and silver eel), as function of growth. Eel samples were obtained from nine sites across the Mediterranean region, that included seven coastal lagoons of different size and ecological structure, and two freshwater habitats corresponding to one river and one lake. A large variability was found in both δ13C and δ15N values, suggesting that eels fed over a broad range of potential food sources. Eels from each location showed specific range values of δ13C, in most sites irrespective of stage, reflecting lagoon- or freshwater-specific carbon sources. A positive correlation was found between individual δ15N values and annual growth rates, suggesting that eels generally seem to feed on prey of higher δ15N values among the trophic resources available in each foraging habitat. This allows individuals to grow faster and to attain earlier the pre-spawning phase (i.e. the silver stage). A better understanding of eel trophic ecology across different life stages and different habitats is one of the prerequisites for the effective management of local stocks.

Population structure of tropical eel (Anguilla bicolor bicolor) in Cikaso River, West Java

A. bicolor bicoloris a tropical eel subspecies that dominate catches in the coastal areas of West Java, and its conservation status is near threatened. Cikaso River, West Java, becomes eel migration path, while unfortunately, information concerning the stock of eel in this river is still inadequate. The objective of this study was to determine the population structure (size distribution, length-weight relationship, and condition factor) ofA. bicolor bicolorin the Cikaso River. The research was carried out in the main streams of the Cikaso River and the coastal marsh of Ciroyom from January to December 2020. Eel samples were collected using lift-net, fishhook, and traps. The number of eels caught is counted, then the total length and weight are measured. We collected nine elvers and 89 yellow eels, but no silver eel was caught during the study. The elver's total length (TL) ranged from 10.2 to 20 cm, and the TL of yellow eel ranged from 20.1 to 42.2 cm. The catch of eel is dominated by the size of 25-30 cm. The growth pattern of eel in the Cikaso River is positive allometric, with the condition factor of eel ranging from 0.450 to 1.917 (1.160±0.3096).

Quality assessment of escaping silver eel (Anguilla anguilla L.) to support management and conservation strategies in Mediterranean coastal lagoons.

Silver eel samples, collected from the lagoons of Fogliano and Caprolace (Italy), were investigated for a broad range of contaminants (29 polychlorinated biphenyls, 9 polybrominated diphenyl ethers, 5 dichlorodiphenyltrichloroethane, 5 chlordanes, hexachlorobenzene, 3 hexachlorocyclohexane, and 5 metals). Concentrations of targeted compounds stand for a general low contamination pattern. Infestation by Anguillicola crassus and virus infections were also examined. No parasite infestation was found, while infected silver eels had a low prevalence for EVEX, and, for the first time in the Mediterranean area, for AngHV-1. Overall, a good quality status of escaping silver eels, for both lagoons, was highlighted by the use of integrative Indexes. A quality assessment of the ecological status of the two lagoons was carried out developing an expert judgment approach, in order to characterize the habitat of eel stocks. A Final Pressure Index was derived, whose values showed an overall limited global anthropogenic impact acting on both lagoons. Results stand for the suitability of an integrated approach to assess lagoon habitats and eel local stocks quality. This could be proposed as a tool to identify sites yielding high quality eel spawners in the Mediterranean region, in order to set up suitable management frameworks, providing elements to appraise and discuss the potential of coastal lagoons in the Mediterranean region towards the recovery of the eel global stock.

Occurrence of Halogenated and Organophosphate Flame Retardants in Sediments and Eels (Anguilla anguilla) From Bizerte Lagoon, Tunisia

Contamination by classic (polybromodiphenyl ethers, PBDEs) and emerging halogenated flame retardants (HFRs) like pentabromobenzene (PBEB), hexabromobenzene (HBB), decabromodiphenyl ethane (DBDPE ) and halogenated norbornenes (HNs), as well as organophosphate flame retardants (OPFRs) were investigated in sediment and eel (Anguilla Anguilla) samples from Bizerte Lagoon, northern Tunisia. This is the first time that OPFR levels have been reported in this area, showing higher concentrations than HFRs: from 9.77 to 164 ng/g dry weight (dw) and from 19.7 to 2154 ng/g lipid weight (lw) for sediment and eel samples, respectively. As regards HFRs, concentrations ranged from 3.30 to 28.5 ng/g dw in sediments and from 4.72 to 151 ng/g lw in eels. The relationship between OPFR and HFR concentrations in sediment and total organic content (TOC) was examined. Results suggested that OPFR levels were significantly correlated with TOC, whereas no correlation was found for HFRs and TOC. The study of potential health risks by eel consumption suggested that there is no significant human health risk associated with the dietary intakes for PBDEs.

American eels produce and release bile acid profiles that vary across life stage.

The American eel (Anguilla rostrata) is an imperilled fish hypothesized to use conspecific cues, in part, to coordinate long-distance migration during their multistage life history. Here, holding water and tissue from multiple American eel life stages was collected and analysed for the presence, profile and concentration of bile acids. Distinct bile acid profiles were identified in glass, elver, yellow eel and silver eel holding waters using ultraperformance liquid chromatography high-resolution mass spectrometry and principal component analysis. Taurochenodeoxycholic acid, taurodeoxycholic acid, cholic acid, deoxycholic acid, taurolithocholic acid and taurocholic acid were detected in whole tissue of American glass eels and elvers, and in liver, intestine and gallbladder samples of late-stage yellow eels. Bile acids were not a major component of silver eel washings or tissue. This study is novel because little was previously known about bile acids produced and emitted into the environment by American eels. Future behavioural studies could evaluate whether any bile acids produced by American eels influence conspecific migratory behaviour.

Chitosan and Oregano Oil Treatments, Individually or in Combination, Used To Increase the Shelf Life of Vacuum-Packaged, Refrigerated European Eel (Anguilla anguilla) Fillets

We investigated the impact of chitosan and oregano essential oil (EO) individually or in combination on the quality of eel fillets in vacuum packaging (VP) and stored under refrigeration (4°C). Treatments studied were (i) control eel fillets stored in VP (E), (ii) eel fillets treated with 0.3% (v/w) oregano EO and stored in VP (E-OR), (iii) eel fillets treated with 2.0% (w/v) chitosan and stored in VP (E-CH), and (iv) eel fillets treated with 2.0% (w/v) chitosan and 0.3% (v/w) oregano EO and stored in VP (E-CH-OR). Treatments E-CH-OR and E-CH significantly reduced counts of mesophilic bacteria, Pseudomonas, Shewanella, and yeasts and molds during storage. Use of chitosan alone or in combination with oregano EO led to a significant reduction in concentrations of trimethylamine nitrogen and total volatile basic nitrogen in fillets, which led to lower concentrations of thiobarbituric acid reactive substances compared with the control samples. The eel samples in the E-CH and E-CH-OR groups were sensorially acceptable during the entire refrigerated storage period of 18 days. Presence of chitosan in the E-CH and E-CH-OR fillets did not negatively affect the taste of the fillets. E-CH fillets received a higher taste score than did E-CH-OR fillets probably because of the distinct and "spicy" lemon taste of chitosan, which was well received by the sensory panel. Based on overall sensory data (based on mean sensory scores of odor and taste), the shelf life was 6 days for the control fillets, 10 days for the E-OR fillets, and >18 days for the E-CH and E-CH-OR fillets stored in VP at 4°C. Overall, chitosan-treated eel fillets had lower microbial loads and a longer shelf life compared with the controls. Chitosan-treated eel fillets were preferred over oregano-treated fillets. Chitosan alone or in combination with oregano could be used as a preservative treatment and shelf-life extender for other seafoods.

Identification and Prevalence of Parasites Isolated from Eels (<i>Anguilla bicolor</i>) Along Migrated Pathway at Serayu River, Central Java

Eels especially Anguilla bicolor has been a major capture species along the migration pathways at Serayu river for both consumption and aquaculture purposes. Yellow eels always exhibited a strong and health when they were caught. However, mass mortalities always found during holding and culture period. Parasites was one of the obstacles of the eels aquaculture. The aims of this study were to observed the health status and parasites investation of eels along the migration pathway. Three capture stations namely Adipala, Sampang and Purwojati were appointed as a sampling sites. Thirty captured eels ranging from 25.48 cm – 28.92 cm were randomly selected at each sites during October to December 2018.Ninety eel samples demonstrated in a good health. Ectoparasites observation discovered that Trichodina was the predominant parasites. Further indentification revealed that they were belongs to T. matsu, T. domerguei and T. jandarica with prevalence rate ranged from 40% to 90%. Whilst Vorticella found at low prevalence and intensity namely; 6.7% and 0.2 respectively. The endoparasites nematodes obtained were Anguillicola and Spirocamallanus with prevalence rate and intensity 3.3%-6.7%, 0.03 – 0.06 and 13.3%, 0.13 respectively. Molecular identification of nematodes demonstrated that they were closely related to Anguillicola crassus and Spirocamallanus philppinensis with similarity 95.40% and 97.93% respectively. There were no genetically differences between two species Anguillicola crassus from Adipala and Sampang. From this study it can be seen that Eels migrated upstream were in a good heatlh. Trichodina, Vorticella, Anguillicola and Spirocamallanus found infestated eels during upstream migration.

MAKANAN ALAMI IKAN SIDAT KACA DI MUARA SUNGAI CIMANDIRI, PELABUHAN RATU, JAWA BARAT

The availability of glass eel stock was relatively abundant in the estuary in Cimandiri rivers Pelabuhan Ratu, West Java. These fish seeds must be managed and used properly, so that it could make a major contribution to the welfare of the society. Food was a key factor to suport the survival and growth of glass eel. Information about the excact food during the glass eel stade was very important. This study aims to investigate the natural food of glass eel in the Cimandiri estuary. Samples of glass eel were taken from Cimandiri Estuary, West Java from October to December 2013. Analysis of the contents of digestive tract were analyzed using the index of preponderance method (combination of occurance frequency and volumetric). The result showed that the natural food of glass eel found in the digestive tract consist of the group of phytoplankton namely class Cyanophyceae (Oschilatoria sp., Coscinosdiscus sp., and Rhizoclonium sp.), class Bacillariophyceae (Navicula sp., and Nitzschia sp., and class Clorophyceae (Chorella sp.). and zooplankton such as Notholca sp., Nauplius sp. The size of natural food of glass eel was in the ranged from of 3,7 – 90,0 µm or range between 1,1% - 24,7% of the width of its mouth opening.

Isolation of some gram-negative bacterial species from naturally infected silver European eel fish (Anguilla anguilla linnaeus, 1758)

The aim of this study is to inform isolations of Shewanella putrefaciens, Aeromonas sobria and A. veronii from the silver European eel fish (Anguilla anguilla) caught from the Gulf of Antalya, Turkey. Three silver eel fish samples as freshly dead (mean weight 75 g) were obtained by a local fisherman. For bacteriological study, inoculations from the head kidney, spleen and liver were made and inoculated onto Brain Hearth Infusion Agar (BHIA-S) supplemented with 1.5 % NaCl. The inoculated petri dishes were incubated at 24 ± 2°C for 72 hours. The end of the incubation period, bacterial colonies were subcultured. For presumptive identification of the bacterial strains, the strains were identified using a variety of phenotypic characteristics. The further identification of the strains was performed with PCR. Clinically, the silver eel samples showed pale gills, losses of scale, necrotic lesions on dorsal, hemorrhagies on the jaws, lateral and ventral sides of the body and around the anus and hemoragic anal fin. At necropsy, the fish had enlarged and pale spleen and the gastrointestinal tract was empty. After 72 hours, 10 bacterial strains were isolated. 6 strains as Shewanella putrefaciens, 2 strains as Aeromonas sobria and 2 strains as A. veronii were identified according to the phenotypical characteristics and PCR study results. The eel fish stocks in natural conditions are decreasing and this problem may be multifactorial such as disease, migration and overhunting. As a result of this study, A. veronii was first isolated from A. anguilla.

Food risk characterization from exposure to persistent organic pollutants and metals contaminating eels from an Italian lake

ABSTRACTMonitoring environmental contaminants in edible animal species is important for the assessment of environmental quality and for food safety as well. In this study, the occurrence of 2,3,7,8 dioxins, and furans, dioxin-like polychlorinated biphenyls, six non-dioxin-like polychlorinated biphenyl indicators (ndl-PCBs), seven polybrominated diphenylethers (PBDEs), four polycyclic aromatic hydrocarbons (PAHs) and four metals (As, Hg, Ni, Pb) was evaluated in 90 European eels (Anguilla anguilla) from Lake Garda. The results on eel samples showed a frequent contamination of dl-PCBs, found at concentrations higher than the maximum limit (ML) provided by European Union in 41 % of the eels. Two PBDE congeners (BDE 47 and BDE 99) were detected in almost all the samples. The contamination by PAHs was found negligible; only one sample had a high concentration of benzo[a]pyrene. Concerning metals, Pb showed concentrations higher than the maximum level (ML) in 77% of the samples, while Ni content could be a cause of acute toxicity due to dermatitis. Extreme consumers (95th percentile) are subjected to an actual risk attributable to dioxins, furans, and mainly dl-PCBs and PBDEs. The contamination of Lake Garda eels is therefore a matter of concern and a constant monitoring of the pollution levels of its freshwater is mandatory.

Feeding habit, length weight relationships and condition factors of the tropical shortfin eel Anguila bicolor bicolor in Banda Aceh waters, Indonesia

The objective of the present study was to analysis the bioecology especially on the feeding habit and growth pattern of the tropical shortfin found in Banda Aceh waters. The survey from October 2016 to September 2017 was conducted in Banda Aceh at two locations, namely in the reservoir of Tibang (Banda Aceh) and Lambaro Skep. A total of 45 samples of eel were caught during the study. The minimum size is 31 cm length and 45 g body weight, while the maximum size is 80 cm in length and 1100 g body weight. Histological analysis of the gonad showed that all samples are female and immature fish. The analysis of the stomach content showed that 12 samples are emptied and 33 samples are containing feed, where the fish fed on crabs, shrimps, small fish, and earthworms. In details, the crab was found in 22 fish samples (66.66%), shrimp was found in 18 samples (54.54%), small fish was found in 14 samples (42.42%), and earthworm was recorded in 3 samples (9.09). Analysis of the length-weight relationship showed that the b value was 3.54 indicate a positive growth pattern with Fulton’s condition factor (K) ranges 8.32 to 10.35 (average 9.32± 0.42) and relative weight condition factor (Wr) ranges 60.92 to 137.70 (average 101.60±16.67), indicates that environmental condition and predator density is stable.

Residual detection of naproxen, methyltestosterone and 17α-hydroxyprogesterone caproate in aquatic products by simple liquid-liquid extraction method coupled with liquid chromatography-tandem mass spectrometry.

In the present study, we aimed to develop a reliable screening method based on liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) for the detection and quantification of naproxen, methyltestosterone and 17α-hydroxyprogesterone caproate residues. The target analytes were extracted from samples of eel, flatfish and shrimp using acetonitrile with 1% acetic acid, followed by liquid-liquid purification with n-hexane. Chromatographic separation was achieved on a reversed-phase analytical column using 0.1% formic acid containing 10 mm ammonium formate in distilled water (A) and methanol (B) as mobile phases. All the matrix-matched calibration curves were linear (R2 ≥ 0.99) over the concentration range of the tested analytes. Recovery at three spiking levels (0.005, 0.01 and 0.02 mg/kg) ranged from 68 to 117% with intra- and inter-day precisions <10%. Five market samples for each matrix (eel, flatfish and shrimp) were collected and tested for method application. In summary, the proposed method is feasible to screen and quantify the analytes with high selectivity in aquatic food products meant for human consumption.

Shelf-life of smoked eel fillets treated with chitosan or thyme oil

The present study examined the effect of natural antimicrobials: Chitosan, thyme oil and their combination, on the shelf-life of smoked eel fillets stored under vacuum packaging (VP) at 4°C. Based on sensory odor data smoked eel fillets had a shelf-life of 35 (control), 42 (thyme treated and>49 (thyme, chitosan-thyme treated) days. The thiobarbituric acid value (TBA) value of the control eel sample was significantly higher than the chitosan-thyme-treated eel samples. The use of chitosan singly, or in combination with thyme oil reduced lipid oxidation (TBA) of the smoked eel samples. A trimethylamine nitrogen (TMA-N) value of 10mgN/100g, could be suggested as an indication of smoked eel spoilage initiation. Control and treated eel reached total volatile basic nitrogen (TVB-N) values of 13.1–31.5mgN/100g below the maximum permissible level of TVB-N in fish and fishery products. Eel samples reached the value of 7.0logcfu/g (Total Plate Count, TPC) on days 35 (smoked) and 42 (thyme treated), whereas both chitosan and chitosan-thyme treated eel samples never reached this limit value. Results of our study show thyme or chitosan (singly, or in combination) inhibit the growth of mesophilic bacteria and extend the shelf-life of smoked eel.

Nutritional properties, oxidative stability, and in vitro digestibility of oils extracted from muscles of wild and breeding eels (Anguilla anguilla)

In this study, physicochemical composition of the wild and breeding eel's muscles were compared. Lipid profiles and scavenging activities were also evaluated. Lipid content of wild eel muscle had the highest oil yield (22.29%) than the breeding one (16.11%). Interestingly, the fatty acids (FA) profiles exhibited a dominance of unsaturated ones exceeding 60% of the total FA content. The omega-3 polyunsaturated FA (PUFA) profiles exhibited a dominance of eicosapentaenoic acid and docosahexaenoic acid in eel samples. The lipid health indexes and the predominance of PUFAs acids in both studied eel muscle samples could meet people's needs. Interestingly, a higher stability of peroxide values was observed during the storage for 30 days at −20 °C, which allows higher oils stability. In vitro digestibility model showed that eel oils were efficiently hydrolyzed by a pancreatic lipase, which suggests the higher assimilation of these oils in the human digestive tract. Practical applications The production of eicosapentaenoic acid and docosahexaenoic acid concentrates from residual sources of marine oils obtained from discarded parts of fish processing have unexplored potential of use in food industry, and oil-based nutraceutical production for obtaining the health benefits can be achieved. The economic activities of fish residues can reduce inappropriate extractive fishing, reducing imports of fish oils while contributing to the ecosystem balance.

Detection of perfluoroalkyl acids and sulphonates in Italian eel samples by HPLC-HRMS Orbitrap

Perfluoroalkyl substances (PFASs) contain one or more carbon-bound hydrogens substituted by fluorine. Since the 1950s, these compounds have been used to manufacture fat- and water-resistant fabrics, paper and food containers, and to produce photographic films, firefighting foams, detergents and insecticides. The widespread use and global distribution of PFASs, have led to their accumulation in the environment. Food, particularly fish and other seafood, is considered the main route of human exposure to PFASs. Consequently, the European Food Safety Authority (EFSA) recommends that more data be collected, to build a database on the contamination levels of the individual PFASs in food, to evaluate a reliable chronic risk to the European consumers. This requires high-sensitivity analytical methods, to increase the number of quantifiable samples and, thereby, improve the credibility of exposure assessments. In this context, the aim of the present research is to develop and validate a sensitive and specific method based on high-performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS) analysis, to monitor the presence of 16 PFASs in Italian eels (Anguilla anguilla) from the Italian Lake Garda. The detection limits (CCα) and detection capability (CCβ) in the order of pg g−1, the recoveries between 80 and 101% and the other validation parameters fulfilled the requirements of Commission Decision 657/2002/EC. The identification and quantification of PFASs, up to 11 in the same sample, showed a similar distribution among 90 eels. Perfluorooctane sulphonic acid (PFOS) and perfluorobutanoic acid (PFBA) were the analytes more frequently found in the eel samples (94 and 82%, respectively).

Quantification of bupivacaine hydrochloride and isoflupredone acetate residues in porcine muscle, beef, milk, egg, shrimp, flatfish, and eel using a simplified extraction method coupled with liquid chromatography-triple quadrupole tandem mass spectrometry.

In this study, a simple analytical approach has been developed and validated for the determination of bupivacaine hydrochloride and isoflupredone acetate residues in porcine muscle, beef, milk, egg, shrimp, flatfish, and eel using liquid chromatography-tandem mass spectrometry (LC-MS/MS). A 0.1% solution of acetic acid in acetonitrile combined with n-hexane was used for deproteinization and defatting of all tested matrices and the target drugs were well separated on a Waters Xbridge™ C18 analytical column using a mobile phase consisting of 0.1% acetic acid (A) and 0.1% solution of acetic acid in methanol (B). The linearity estimated from six-point matrix-matched calibrations was good, with coefficients of determination ≥0.9873. The limits of quantification (LOQs) for bupivacaine hydrochloride and isoflupredone acetate were 1 and 2ngg-1, respectively. Recovery percentages in the ranges of 72.51-112.39% (bupivacaine hydrochloride) and 72.58-114.56% (isoflupredone acetate) were obtained from three different fortification concentrations with relative standard deviations (RSDs) of <15.14%. All samples for the experimental work and method application were collected from the local markets in Seoul, Republic of Korea, and none of them tested positive for the target drugs. In conclusion, a simple method using a 0.1% solution of acetic acid in acetonitrile and n-hexane followed by LC-MS/MS could effectively extract bupivacaine hydrochloride and isoflupredone acetate from porcine muscle, beef, milk, egg, shrimp, flatfish, and eel samples.