The differences of toxin accumulation and elimination among oyster, mussel and scalllop were investigated in relation to the density of Alexandrium tamarense. The toxicity of oyster, mussel and scallop increased in association with the cell numbers. However, the ratios of the toxicity level to the cell number were different among the bivalve species. The highest accumulations were found in scallop and mussel (about 3 times higher than in oyster). The elimination rate of toxicity in the oyster was fast. But, after the disappearance of A. tamarense, the toxicity of scallop was retained for a long period. During the period of increasing plankton growth, the proportions of toxins in the body of bivalves reflected those in the plankton. But when the plankton density started decreasing, the toxin ratios in the bivalves changed on a daily basis, presumably owing to metabolism of the toxins in the bivalves.

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An electrogenerated chemiluminescence high performance liquid chromatography (ECL-HPLC) for ofloxacin (OFLX) using tris (2, 2′-bipyridine) ruthenium (II) was developed and applied for residue analysis in chicken tissues. OFLX was extracted from tissues by homogenizing with 0.1mol/L phosphate buffer (pH 12)-acetonitrile (1:3, v/v) and centrifuging the mixture. The supernatant was shaken with n-hexane saturated with acetonitrile. After having been centrifuged, the lower layer was evaporated to dryness under reduced pressure and the residue was dissolved in acetonitrile-0.05mol/L NaH₂PO₄ (pH 2.4) (20:80, v/v) and analyzed by ECL-HPLC. The mean recoveries of OFLX from chicken tissues were 66-102%. The detection limit of this method was 10ng/g (0.01ppm) of OFLX. The correlation between ECL-HPLC and FL-HPLC was excellent.

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The present study was carried out to examine the content of cyanide in basidiomycetes on the market and those in their natural habitat, and to investigate the chemical form of cyanide in basidiomycetes and the effect of cooking.
The chemical form of cyanide in basidiomycetes was suggested to be free, because there was no significant difference in the quantities of cyanide found upon distillation of basidiomycetes immediately and after incubation with two kinds of β-glucosidase for 16 hours. The content of cyanide was examined in a total of 85 samples of 54 kinds of basidiomycetes on the market and those in their natural habitat, and cyanide was detected in 44 samples of 18 kinds. The content of cyanide in basidiomycetes on the market was the highest in Tricholoma giganteum at the level of 86-283μg/g (n=11), and was high in Grifola frondosa at 1.8-46μg/g (n=6), and in Pleurotus eryngii at 1.1-26μg/g (n=7). The contents in sample in the natural habitat were less than 1.0μg/g. The remaining percentage of the cyanide in T. giganteum after grilling for 6 minutes was 65%, while that after boiling for 3 minutes was 46% (27% in basidiomycetes and 19% in broth).
The level of residual cyanide in T. giganteum after cooking might be sufficient to cause poisoning with symptoms such as vomiting.

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In order to evaluate the endocrine-disrupting effects of the styrene oligomers in polystyrene, used in cups for instant noodles, we examined the effects of styrene monomer (SM), styrene dimers (SD: NSD-01, 08, 09) and styrene trimers (ST: NST-01, 02, 03) on the estrogen receptor (ER) binding assay, the androgen receptor (AR) binding assay, the proliferation of MCF-7 human breast cancer cells, the steroidogenesis in Leydig cells of rats and the uterotrophic assay of immature rats. SM, SD and ST did not significantly bind to ER or AR of rats, did not induce the proliferation of MCF-7 cells, did not inhibit testosterone production in Leydig cells of rats, and did not induce estrogen-like alteration in the uterus and vagina of immature female rats. Therefore, it appears that these SM, SD and ST have no endocrine-disrupting effects through ER, AR and steroidogenesis mechanisms.

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Three species of bivalves (mussel, hard clam, and surf clam) were collected in 1990-98 in Ibaraki Prefecture, Japan, and assayed for toxicity and composition of paralytic shellfish poison (PSP). All the species of bivalves were found to be toxic every or every other year; they became toxic in March or early April and nontoxic in May. Their digestive glands showed the highest toxicity scores, ranging from 100 to 300MU/g. Irrespective of the species and parts (“muscle” and “visceral” parts), PSP was composed almost exclusively of protogonyautoxins (PXs) 1, 2 and gonyautoxins (GTXs) 1-4. The PSP composition profile, however, was species-specific and differed between the two parts in each species. The ratio of N1-OH toxins (GTX1, GTX4) to N1-H toxins (GTX2, GTX3) differed significantly among the species. The ratio also differed between the two parts of both clams, though not in the mussel. This suggested that species- and organ-specific metabolism could have taken place in the viscera.
In each species, on the other hand, the ratio of α-epimer (GTX1) to β-epimer (GTX4) at position C11 tended to increase up to the equilibrium point of 3:1.

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Surf clam Pseudocardium sachalinensis was collected from coastal waters of Ibaraki Prefecture and dissected into various parts, which were analyzed for paralytic shellfish poisons (PSPs) by HPLC. In all the parts, PSP was composed almost exclusively of protogonyautoxin (PX) and gonyautoxins (GTXs) 1-4. The relative amounts of those components, however, differed among the parts. Overall, the ratio of GTX (1, 4) (N1-OH carbamate toxins) to GTX (2, 3) (N1-H carbamate toxins) clearly differed between the visceral parts and the muscle parts, suggesting the involvement of enzymatic reaction. When added to the visceral extract, GTX (1, 4) (N1-OH toxins) was for the most part converted into GTX (2, 3) (N1-H toxins). This, along with some other data, suggested that biotransformation of GTX (1, 4) to GTX (2, 3) takes place in surf clam viscera.

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The quantities of the sweetener aspartame (APM) and its decomposed product, diketopiperazine (DKP), in chocolate, soy sauce and miso paste were determined by high performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry with selected-ion monitoring. APM and DKP were extracted from the foodstuffs with water and a solid-phase extraction was carried out. The extracted APM and DKP were separated on an analytical C-4 reversed-phase column with ammonium formate buffer (0.05mol/L, pH 4.0) containing 20% methanol as the mobile phase and o-hydroxybenzamide as the internal standard (IS). In the negative mode, APM, DKP and IS were monitored at m/z 293, m/z 261 and m/z 136, respectively. The limit of determination for APM and DKP in the sample was 5μg/g and the recoveries of APM and DKP were 53-83% and 69-101%, respectively. This method enabled the determination, for the first time, of DKP in chocolate, soy sauce and miso paste.

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Simultaneous determination of 71 pesticides in cereals by HPLC and GC was studied. The pesticides were extracted by SFE with collection using Extrelut^®, defatted with Extrelut^®+C₁₈ and cleaned up by using GPC and a Sep-Pak^® Florisil cartridge. The test solution was subjected to HPLC with UV and FL detection, GC with FPD, FTD or ECD and GC/MS (SIM).
Surveillance of imported cereals (wheat, corn) was carried out by the proposed methods. Malathion, fenitrothion, chlorpyrifos methyl, cyfluthrin were determined by GC and confirmed by GC/MS (SIM). Iprodion, difenoconazole, etofenprox were determined by HPLC and confirmed by photodiodo-array detection or GC/MS (SIM).

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A simple and simultaneous determination of residual phosphorus-containing amino acid herbicides such as bilanafos (BIA), glufosinate (GLU) and glyphosate (GLY) in agricultural products by HPLC with fluorescence detection was developed. The herbicides were extracted from agricultural products with water. The crude extract was cleaned up on Sep-Pak PS-2 Plus and Bakerbond spe (Sulfonic acid) cartridges, then derivatized with the fluorogenic labeling reagent, 9-fluorenylmethyl chloroformate. The herbicides were detected by measuring the fluorescence at λ_ex 255nm and λ_em 310nm. The recoveries of 3 herbicides spiked at 2.0μg/g in agricultural products were within the range of 69.7-126.8%. The detection limits were 0.02-0.04μg/g.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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