Contamination of shellfish from Shanghai seafood markets with paralytic shellfish poisoning and diarrhetic shellfish poisoning toxins determined by mouse bioassay and HPLC

This paper reports the results of investigations of shellfish toxin contamination of products obtained from Shanghai seafood markets. From May to October 2003, 66 samples were collected from several major seafood markets. Paralytic shellfish poisoning (PSP) and diarrhetic shellfish poisoning (DSP) toxins in shellfish samples were monitored primarily by a mouse bioassay, then analysed by HPLC for the chemical contents of the toxins. According to the mouse bioassay, eight samples were detected to be contaminated by PSP toxins and seven samples were contaminated by DSP toxins. Subsequent HPLC analysis indicated that the concentrations of the PSP toxins ranged from 0.2 to 1.9 microg/100 g tissues and the main components were gonyautoxins 2/3 (GTX2/3). As for DSP, okadaic acid was detected in three samples, and its concentration ranged from 3.2 to 17.5 microg/100 g tissues. Beside okadaic acid, its analogues, dinophysistoxins (DTX1), were found in one sample. According to the results, gastropod (Neverita didyma) and scallop (Argopecten irradians) were more likely contaminated with PSP and DSP toxins, and most of the contaminated samples were collected from Tongchuan and Fuxi markets. In addition, the contaminated samples were always found in May, June and July. Therefore, consumers should be cautious about eating the potential toxic shellfish during this specific period.

Hydrophilic interaction liquid chromatography–mass spectrometry for the analysis of paralytic shellfish poisoning (PSP) toxins

Hydrophilic interaction liquid chromatography (HILIC) was examined for the separation of paralytic shellfish poisoning (PSP) toxins using the stationary phase TSK-gel Amide-80. The parameters tested included type of organic modifier and percentage in the mobile phase, buffer concentration, pH, flow rate and column temperature. Using mass spectrometric (MS) detection, the HILIC column allowed the determination of all the major PSP toxins in one 30 min analysis with a high degree of selectivity and sensitivity. The high percentage of organic modifier in the mobile phase and the omission of ion pairing reagents, both favored in HILIC, provided limits of detection (LOD) in the range 50-100 nM in selected ion monitoring (SIM) mode on a single quadrupole LC-MS system. LOD in selected reaction monitoring (SRM) mode on a sensitive triple quadrupole system were as low as 5-30 nM. Excellent linearity of response was observed.

A rapid detection method for paralytic shellfish poisoning toxins by cell bioassay

We report here a rapid detection method for paralytic shellfish poisoning (PSP) toxins using a cultured neuroblastoma cell line, modified from the bioassay system previously established by Manger et al. [Manger, R.L., Leja, L.S., Lee, S.Y., Hungerford, J.M., Kirkpatrick, M.A., Yasumoto, T., Wekell, M.M., 2003. Detection of paralytic shellfish poison by rapid cell bioassay: antagonism of voltage-gated sodium channel active toxins in vitro. J. AOAC Int. 86 (3), 540-543]. In the present study, we made two major modifications to the previous method. The first is the use of maitotoxin, a marine toxin of ciguatera fish poisoning, which enables the incubation period to be reduced to 6 h when applied to the microplate 15 min prior to the end of the incubation. The second is the use of WST-8, a dehydrogenase detecting water-soluble tetrazolium salt for determining the target cell viability, which permits the omission of a washing step and simplifies the counting process. In addition, we attempted to reduce the required materials as much as possible. Thus, our modified method should be useful for screening the PSP-toxins from shellfish.

First report of saxitoxin in Finnish lakes and possible associated effects on human health

This study is the first report of saxitoxin in cyanobacterial blooms in Finland. Bloom samples (n = 50) were collected from Finnish freshwater sites during summer months of 2002 and 2003. These samples were screened for the presence of paralytic shellfish toxins (PSTs) using the Jellett rapid PSP screening test. Samples testing positive for PSTs (n = 7) were further analyzed with saxiphilin- and voltage-gated sodium channel [(3)H]-STX-binding radioreceptor assays and liquid chromatography using fluorescence and mass spectrometric analysis. The results indicated that saxitoxin (STX) was the only PST analogue in the samples and that it was present in high concentrations, as much as 1 mg L(-1). Microscopic analysis revealed that 95%-100% of the phytoplankton in the positive samples consisted of Anabaena lemmermannii. The trophic status of lakes in which STX-containing blooms were found varied from oligotrophic to hypertrophic. All the lakes had high nitrogen-to-phosphorus ratios. In some instances, samples had been collected from sites where swimmers had reported adverse health effects, and in three such cases, reported adverse health effects were associated with sites from which samples testing positive for STX had been received. Symptoms of fever, eye irritation, abdominal pains, and skin rash were reported in children aged 2-10 years after exposure to the water. These were not the adverse human symptoms typical of STX poisoning; rather, they represented acute effects often reported following recreational exposure to cyanobacterial blooms.

First report in a river in France of the benthic cyanobacterium Phormidium favosum producing anatoxin-a associated with dog neurotoxicosis

The first identification of anatoxin-a in a French lotic system is reported. Rapid deaths of dogs occurred in 2003 after the animals drank water from the shoreline of the La Loue River in eastern France. Sediments, stones and macrophytes surfaces at the margin of the river were covered by a thick biofilm containing large quantities of several benthic species of filamentous, non-heterocystous cyanobacteria. Known cyanotoxins, such as microcystins, saxitoxins and anatoxins were screened from biofilm samples by biochemical and analytical assays. A compound with similar UV spectra to the anatoxin-a standard was detected by high-performance liquid chromatography (HPLC) coupled with photo-diode array detector. This toxin was further identified by HPLC coupled with a UV detector and by electrospray ionisation-Quadrupole-Time-Of-Flight mass spectrometer, and confirmed by tandem mass spectrometry. These two techniques were necessary to discriminate anatoxin-a in phenylalanine-containing matrices such as liver samples of poisoned dogs. The toxin and the aromatic amino acid, phenylalanine, present the same pseudomolecular ion at m/z 166, but have differing fragmentation patterns, retention times and UV spectra. Finally, several cyanobacterial strains were isolated from the green biofilm and tested for anatoxin-a production. Phormidium favosum was identified as a new anatoxin-a producing species.

Selective detection of saxitoxin over tetrodotoxin using acridinylmethyl crown ether chemosensor

At pH 7.1, saxitoxin decomposes to produce a trace impurity that can interfere with fluorescence sensing when using irradiation wavelengths near 325 nm. The fluorophore acridine is found to be a suitable component of arylmethyl crown ether chemosensors for the fluorescent detection of saxitoxin. These sensors are selective for the detection of saxitoxin over tetrodotoxin.

Sodium channel mutation leading to saxitoxin resistance in clams increases risk of PSP

Bivalve molluscs, the primary vectors of paralytic shellfish poisoning (PSP) in humans, show marked inter-species variation in their capacity to accumulate PSP toxins (PSTs) which has a neural basis. PSTs cause human fatalities by blocking sodium conductance in nerve fibres. Here we identify a molecular basis for inter-population variation in PSP resistance within a species, consistent with genetic adaptation to PSTs. Softshell clams (Mya arenaria) from areas exposed to 'red tides' are more resistant to PSTs, as demonstrated by whole-nerve assays, and accumulate toxins at greater rates than sensitive clams from unexposed areas. PSTs lead to selective mortality of sensitive clams. Resistance is caused by natural mutation of a single amino acid residue, which causes a 1,000-fold decrease in affinity at the saxitoxin-binding site in the sodium channel pore of resistant, but not sensitive, clams. Thus PSTs might act as potent natural selection agents, leading to greater toxin resistance in clam populations and increased risk of PSP in humans. Furthermore, global expansion of PSP to previously unaffected coastal areas might result in long-term changes to communities and ecosystems.

Accumulation and depuration rates of paralytic shellfish poisoning toxins in the shore crab Telmessus acutidens by feeding toxic mussels under laboratory controlled conditions

Accumulation and depuration rates of paralytic shellfish poisoning toxins (PSP) in the crab Telmessus acutidens were investigated by feeding toxic and non-toxic mussels under laboratory controlled conditions. The crab accumulated toxins in the hepatopancreas in proportion to the amount of toxic mussels they ingested, and the toxicity in the crab hepatopancreas became 3.2 fold of that in the prey mussels after 20 days of feeding. During depuration, a fast reduction of the total toxicity was observed in the crab, and the retention rate of the toxicity after 5 days depuration with feeding of non-toxic mussels was 45.8+/-18.7%. The reduction of the toxicity was moderated in the later period of depuration, and the retention rates of the total toxicity after 10 and 20 days were 54.1+/-29.8% and 14.5+/-9.0%, respectively. The toxin profiles in the crab and mussel were investigated by high performance liquid chromatography, and reductive conversions of the toxins were observed when the toxins were transferred from the mussel to the crab. Consequently, high concentrations of GTX2 and GTX3, and STX that were not detected in the prey mussels, were found in the crab.

Quantitative 1H NMR with External Standards: Use in Preparation of Calibration Solutions for Algal Toxins and Other Natural Products

We examine the use of external standards for quantitative measurement by 1H NMR of solution concentrations of natural products and other low molecular weight, hydrogen-containing compounds and show that precision and accuracy ca. 1% is obtainable with a commercial 11.7 T spectrometer when standards and analytes are contained in separate but identical sealed precision glass NMR tubes. Numerous factors contributing to the intensity of the NMR signals are evaluated. Precise measurements of 360 degrees pulse lengths for each sample provide direct corrections for variations in probe Q-factor that enable samples in different solvents to be compared, provided single-coil excitation and detection is used throughout. Samples need not be prepared in deuterated solvents if the 1H spectra of the solvents are simple enough for peak suppression by presaturation. The approach is particularly suitable for hazardous materials kept in sealed tubes and for the preparation of certified calibration solution reference materials for use with LC-MS and other techniques where deuterated solvents should be avoided.

[Analysis of paralytic shellfish poison of bivalves in seafood market in Guangzhou]

OBJECTIVE

The investigations of the paralytic shellfish poisoning (PSP) from Huangsha seafood market of Guangzhou was performed to assess the risk of PSP in bivalves.

METHODS

The concentration and profiles of PSP toxins in bivalves were determined by mouse bioassay of AOAC and high-performance liquid chromatography (HPLC). The risk assessment of PSP in bivalves was conducted with FAO and Chinese Administration Organization of Fish Culture and Seaport.

RESULTS

The content of PSP detected was lower than the safe standard (4 MU/g meat) in all of the 84 samples, one of which had the highest toxicity with 1.84 MU/g muscle. These results suggested that the bivalves in seafood market was safe to feed. It was 9 samples' gland in 2 species that be detected to have PSP in the bivalves being researched, the muscles had few PSP. The concentration of PSP in one sample's gland exceeded the threshold of FAO (4 MU/g) with 14.52 MU/g meat, and the profiles of PSP in the gland were B1, GTX2/3, GTX1/4 and C according to HPLC.

CONCLUSION

These results suggested that both of the concentration and detection rate of PSP of bivalves in seafood market in Guangzhou were low as a whole, but the content and discovery rate of PSP were far higher in glands than in the muscles, and the PSP content in one gland exceeded the threshold of Standard. The levels of PSP contamination in shellfish was characteristic of season. The toxins level in shellfish were the maximum in spring, but the frequency of toxins detected in shellfish was higher in summer and autumn, so the detection and risk assessment of PSP in bivalves from seafood market was essential in the future.

Use of sodium transfer tissue biosensor (STTB) for monitoring of marine toxic organism

A highly sensitive sodium (Na+) transfer tissue biosensor (STTB) was designed using a frog bladder membrane to measure paralytic shellfish poisons (PSP). The STTB consists, of a Na+ electrode covered by the membrane, which was then integrated into a flow-through system for continuous measurements. In the absence of Na+ channel blocker, active transfer of Na+ occurred from inside to outside across the frog membrane. When the STTB was used to measure the Na+ -dependent dissociation of PSP, it was able to detect PSB at a level contained in a single cell. However, 5 fg or higher (100 cells or more) is needed for accurate and reproducible measurements. The toxicity obtained by the STTB was significantly correlated (r = 0.9449) to that determined by the HPLC. Therefore, the simple method of the STTB can be used not only to detect a low level PSP in toxic plankton populations, but also to monitor poisons in shellfish.

Paralytic shellfish toxins in the chocolata clam, Megapitaria squalida (Bivalvia: Veneridae), in Bahía de La Paz, Gulf of California

Occurrence and toxic profiles of paralytic shellfish toxins (PST) in the chocolata clam Megapitaria squalida were investigated. From December 2001 to December 2002, 25 clams were obtained monthly from Bahia de La Paz, Gulf of California. Additionally, net (20 microm) and bottle phytoplankton samples were also collected to identify toxic species. Toxins were analyzed by HPLC with post-column oxidation and fluorescence detection. Toxicity in the clam was low and varied from 0.14 to 5.46 microg/STXeq/100 g. Toxicity was detected in December, March, April, June, and August. Toxin profile was composed mainly by STX, GTX2, GTX3, dcGTX2, dcGTX3, C2, dcSTX and B1. Gymnodinium catenatum was the only PST-producing dinoflagellate identified in the phytoplankton samples throughout the study period. G. catenatum was observed mainly in net samples from December 2001 to December 2002; however, in bottle samples, G. catenatum was only observed in five months. Highest abundance (2600 cells l(-1)) was observed in March and the lowest (160 cells l(-1)) in June. G. catenatum mainly formed two-cell chains and rarely four or eight. The presence of PST in net phytoplankton samples support the fact that G. catenatum is the main source of PST in the clams. This study represents the first report of PST toxins in the chocolata clam from Bahia de La Paz.

Paralytic shellfish poisoning (PSP) in Margarita Island, Venezuela

A severe outbreak of Paralytic Shellfish Poisoning (PSP) occurred in Manzanillo and Guayacán, northwestern coast of Margarita Island, Venezuela, between August and October 1991. A bloom of dinoflagellates including Prorocentrum gracile, Gymnodinium catenatum and Alexandrium tamarense seemed to be responsible for this outbreak. Levels of PSP toxins in mussels (Perna perna) exceeded the international safety limit of saxitoxin, 80 microg STX/100 microg meat. PSP toxin values varied between 2548 and 115 microg STX/100 g meat in Manzanillo, and between 1422 and 86 microg STX/100 g meat in Guayacán. At both locations, the highest levels were detected in August, when 24 patients exhibited typical symptoms of PSP toxicity after consuming cooked mussels (16 required hospitalization). A high pressure liquid chromatographic (HPLC) procedure was recently used on the 1991 samples. The major toxin detected in samples of both locations was decarbamoyl saxitoxin (dcSTX), but low concentrations of saxitoxin were also found in Manzanillo samples. Gonyautoxins GTX1, GTX2 and GTX3 were detected only at Guayacán, while in both locations, decarbamoylgonyatouxin (dcGTX2,3) toxins were detected. These findings represent the first time that causative toxins of PSP in Venezuela have been chemically identified, and confirm the presence of dcSTX and dcGTX in mussels from the Caribbean Sea. The presence of dcSTX and dcGTX in shellfish is indicative that Gymnodinium catenatum was a causative organism for outbreak of PSP.

Feasibility of reduction in use of the mouse bioassay: presence/absence screening for saxitoxin in frozen acidified mussel and oyster extracts from the coast of California with in vitro methods

In the United States, the detection of paralytic shellfish poisoning (PSP) for regulatory purposes relies on the mouse bioassay (MBA). Using a saxitoxin presence/absence test could reduce animal usage significantly. Three in vitro methods, the RIDASCREEN Saxitoxin kit, MIST Alert, and a 5 h neuroblastoma assay, were evaluated in parallel with the MBA using 106 twice-frozen, acidified extracts from California-grown mussel and oyster tissues. For each assay, a cutoff point was established whereby data below or equal to that point were scored as negative and were assigned a score of zero. Data above the cutoff were considered positive and assigned a score of one. Pearson correlation coefficients were generated. The RIDASCREEN, MIST Alert, and neuroblastoma bioassay correlated to the MBA at 0.849, 0.853, and 0.832 when used for presence/absence detection. These data suggest that a reduction in MBA usage could be achieved in the surveillance of California-grown mussels and oysters for PSP-associated toxins. Correlation data between the in vitro assays, cost comparisons, and the potential for false negatives and false positives were examined. Implications of these methodologies in protecting public health are discussed.

[Presence of the dinoflagellates Ceratium dens, C. fusus and C. furca (Gonyaulacales: Ceratiaceae) in Golfo de Nicoya, Costa Rica]

Harmful Algae Blooms (HAB) are a frequent phenomenon in the Gulf of Nicoya, Costa Rica, as in other parts of the world. The morphology and physiology of these microalgae are important because HAB species have adaptive characteristics. The production of high concentrations of paralytic toxins by Ceratium dinoflagellates has only been documented at the experimental level. However, this genus has been associated with the mortality of aquatic organisms, including oyster and shrimp larva, and fish, and with decreased water quality. Recently, fishermen reported massive mortality of encaged fish near Tortuga Island (Gulf of Nicoya). Samples were taken from an algal bloom that had produced an orange coloration and had a strong foul-smelling odor. Ultrastructural details were examined with scanning electron microscopy. The dinoflagellates Ceratium dens, C. furca and C. fusus were found in samples taken at the surface. The cell count revealed four million cells of this genus per liter. The morphological variability of these species is high; therefore electron microscopy is an useful tool in the ultrastructural study of these organisms. This is the first time that three Ceratium species are reported concurrently producing harmful blooms in Costa Rica.

PSP-toxicification of the carnivorous gastropod Rapana venosa inhabiting the estuary of Nikoh River, Hiroshima Bay, Hiroshima Prefecture, Japan

During surveillance on the toxicity of invertebrates such as bivalves inhabiting the coasts of Hiroshima Bay in 2001 and 2002, the carnivorous gastropod rapa whelk Rapana venosa collected in the estuary of Nikoh River, was found to contain toxins which showed paralytic actions in mice; the maximum toxicities (as paralytic shellfish poison, PSP) were 4.2 MU/g (May 2001) and 11.4 MU/g (April 2002). Their total toxicities were 224 and 206 MU/viscera of one specimen throughout the monitoring period. Attempts were made to identify the toxic principle in the gastropod. The viscera were extracted with 80% ethanol acidified with acetic acid, followed by defatting with dichloromethane. The aqueous layer obtained was treated with activated charcoal and then applied to a Sep-Pak C18 cartridge. The unbound toxic fraction was analyzed by high-performance liquid chromatography techniques. The gastropod toxin was rather unexpectedly identified as PSP. It was comprised of high toxic component (gonyautoxin-3; GTX3, GTX2, saxitoxin; STX) as the major components, which accounted for approximately 91 mol% of all components along with C1 and C2, which are N-sulfocarbamoyl derivatives. Judging from their toxin patterns, it is suggested that the PSP toxification mechanism of the gastropod that PSP toxins produced by phytoplankton such as Alexandrium tamarense, are transferred to and accumulated in plankton feeders such as the short-necked clam, and then transferred to this carnivorous rapa whelk R. venosa through predation.

Quantitation of paralytic shellfish toxins using mouse brain synaptoneurosomes

A membrane potential assay based on synaptoneurosomes prepared from mouse brain was evaluated further for its utility in estimating saxitoxin and related bioactives. Saxitoxin concentrations quantitated in mussel extracts by the synaptoneurosomal technique correlated well with spiked concentrations in these samples (r2 = 0.995; slope=1.048). Other experiments found that the synaptoneurosomal assay can detect saxitoxin-like bioactives in zooplankton samples and the concentrations measured were consistent with preliminary estimations of saxitoxin equivalents using the [3H] saxitoxin receptor binding technique. Veratrine, a mixture of alkaloids that activate sodium channels, had similar potential as a substitute for veratridine in the synaptoneurosomal assay. The results provide additional evidence that the mouse brain synaptoneurosomal membrane potential assay has excellent capability for quantitation of saxitoxin-like activity in shellfish tissues and may also be applied to zooplankton samples.

Liquid chromatography/quadrupole time-of-flight mass spectrometry for determination of saxitoxin and decarbamoylsaxitoxin in shellfish

Saxitoxin (STX) and decarbamoylsaxitoxin (dcSTX) were determined by liquid chromatography with quadrupole time-of-flight mass spectrometry (Q-TOF MS). A shellfish tissue was extracted with 0.1 mol/l HCl under ultrasonication, and cleanup of extract was accomplished by solid-phase extraction with a C18 cartridge. Chromatographic separation was carried out on a C18 column (150 mm x 2.1 mm, 3.5 microm) with gradient elution of MeOH-H2O (20:80) containing 0.05% heptafluorobutyric acid and MeOH-H2O (15:85) containing 0.05% acetic acid. The protonated molecule [M + H]+ ions at m/z 257 for dcSTX and 300 for STX were selected in precursor ion scanning for Q-TOF MS in the positive electrospray ionizaion mode. Average recoveries and relative standard deviations, by analyzing samples spiked at a level of 0.1, 0.8 or 1.6 microg/g, were 84-92 and 8-14%, respectively. Identification of the presence of the toxins in shellfish tissues was based on the structural information offered by Q-TOF MS.

Occurrence of saxitoxins as a major toxin in the ovary of a marine puffer Arothron firmamentum

Eleven male and 14 female specimens of a marine puffer Arothron firmamentum were collected from Oita and Iwate Prefectures, Japan. The toxicity assay using mouse showed that only ovary and skin of the female specimens were toxic, the toxicity scores being 5-740 as paralytic shellfish poison and <5-30 MU/g as tetrodotoxin (TTX), respectively. The toxin extracts from the both tissues were then treated with cartridge columns, and subjected to high performance liquid chromatography and liquid chromatography-mass spectral analyses. In the analyses, saxitoxin (STX) and decarbamoylSTX (dcSTX) were identified as the major toxins in the ovary, while the skin contained only TTX.

A survey for paralytic shellfish poisoning (PSP) in Vancouver Harbour

Shellfish samples were collected from seven inter-tidal and two sub-tidal sites between 23 May and 8 June 1999 in Vancouver Harbour and were analysed for paralytic shellfish poisoning (PSP) using a mouse bioassay. PSP was detected in mussels collected at four sampling sites in English Bay and Burrard Inlet, at a concentration below 20 microg saxitoxin equivalents (STXeq)/100 g wet weight.

Quantitative determination of paralytic shellfish poisoning toxins in shellfish using prechromatographic oxidation and liquid chromatography with fluorescence detection: interlaboratory study

An interlaboratory study was conducted for the determination of paralytic shellfish poisoning (PSP) toxins in shellfish. The method used liquid chromatography with fluorescence detection after prechromatographic oxidation of the toxins with hydrogen peroxide and periodate. The PSP toxins studied were saxitoxin (STX), neosaxitoxin (NEO), gonyautoxins 2 and 3 (GTX2,3 together), gonyautoxins 1 and 4 (GTX1,4 together), decarbamoyl saxitoxin (dcSTX), B-1 (GTX5), C-1 and C-2 (C1,2 together), and C-3 and C-4 (C3,4 together). B-2 (GTX6) toxin was also included, but for qualitative identification only. Samples of mussels, both blank and naturally contaminated, were mixed and homogenized to provide a variety of PSP toxin mixtures and concentration levels. The same procedure was followed with samples of clams, oysters, and scallops. Twenty-one samples in total were sent to 21 collaborators who agreed to participate in the study. Results were obtained from 18 laboratories representing 14 different countries.

Algal biotoxins of marine origin: new indications from the European Union

Marine biotoxins, more or less complex molecules with various origins that can accumulate in the tissues of fish products through the food chain, are reviewed. The EU, aware of the danger incurred in eating certain fish products, has issued a set of hygiene and health directives for the purpose of preventing disease and safeguarding consumer health. In particular, directive 91/492/EEC, of 15 July 1991, lays down the sanitary norms applicable to the production and commercialization of live bivalve molluscs, echinoderms, tunicates and marine gastropods and regulates the whole system involving these products from their origin to consumption. More recently, through Commission Decision dated 15 March 2002 (EC OJ 175/62 of 16.3.2002) the EU has set new standards for the implementation of directive 91/492/EEC with respect to the maximum levels and analysis methods for some marine biotoxins.

Improved solid-phase extraction procedure in the analysis of paralytic shellfish poisoning toxins by liquid chromatography with fluorescence detection

The analysis of shellfish extracts for the determination of paralytic shellfish poisoning (PSP) toxins by liquid chromatography with fluorescence detection repeatedly showed the presence of a compound suspected to interfere with gonyautoxin 4. The first aim of this study was to confirm by liquid chromatography coupled to tandem mass spectrometry that this compound was not gonyautoxin 4. The second part of this work was to improve a nonvolumetric C(18) solid-phase extraction (SPE) procedure to evaluate the removal of the interference associated with the recovery of PSP toxins. The cleanup procedure was modified into a volumetric SPE procedure and proved to efficiently and totally remove the interference while recovering from 78 to 85% of the PSP toxins available as commercial standards (saxitoxin, neosaxitoxin, gonyautoxins 1-4) and considered as major PSP toxins in human intoxication, with 85% recovery for gonyautoxin 4. The efficiency of this cleanup procedure was checked on shellfish extracts containing this interference and originating from France and Turkey.