α-Lipoic acid has recently been permitted for use in foodstuffs and is contained in tablets and capsules. Although α-lipoic acid is synthesized from adipic acid, the safety of polymers produced during the purification and drying processes has been an issue of concern. Hence, we examined the safety profiles of thermally denatured polymer (LAP-A) and ethanol-denatured polymer (LAP-B) produced in the manufacturing process of α-lipoic acid. Furthermore, we conducted structural analysis of these polymers by ¹H-NMR and FAB-MS spectroscopy. In a consecutive ingestion test, male and female mice ingested diet containing 0.1 and 0.2% LAP-A and -B for 4 weeks. Blood uric acid, potassium and lactate dehydrogenase (LDH) tended to increase without dose-dependency. Relative liver weights were also increased. However, male dogs that were orally administered LAP-B (500 mg/kg) once did not show any abnormalities in blood parameters or general condition. These findings indicate that α-lipoic acid polymers are not acutely toxic; however, chronic ingestion of these polymers may affect liver and kidney functions.

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A multiplex PCR (M-PCR) method was developed for the detection of DNAs of plant and three allergenic substances (wheat, buckwheat, and peanut) in foods. Genomic DNAs were extracted from allergenic substances with a commercial ion-exchange type kit. Four primer pairs suitable for the specific detection of plant DNA were designed to establish a M-PCR method detecting simultaneously the specific DNAs of plant and allergenic substances. Our four designed primer pairs and the primer pair described in the Japanese official method were applied to the specific detection of plant DNA. A primer pair of Plant01-5' and Plant01-3' (amplicon size; 161 bp) was the most suitable for the specific detection of plant DNA. M-PCR was performed to detect the specific DNAs of allergenic substances using four primer pairs, a pair of Plant01-5' and Plant01-3', and three pairs for allergenic components described in the Japanese official method. The four specific PCR bands were simultaneously amplified from genomic DNAs of allergenic substances. The proposed method is simple, rapid and inexpensive.

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A method for simultaneous determination of Dichlorvos (DDVP), Trichlorfon (DEP) and Naled (BRP) in fruits and vegetables by liquid chromatography with tandem mass spectrometry (LC/MS/MS) was developed. Pesticides were extracted with ethyl acetate together with phosphoric acid and anhydrous sodium sulfate, followed by an ENVI-Carb cartridge cleanup. Phosphoric acid prevented BRP from being converted to DDVP during extraction of pesticides from the sample. When the sample was dissolved in acetonitrile in a silanized glass vial, BRP and DEP remained intact. Mass spectral acquisition was performed with a TurboIonSpray (ESI) interface in the positive mode by applying multiple reaction monitoring. In LC separation, an ODS column was used with acetic acid-ammonium acetate-methanol as a mobile phase. Recoveries from 8 fruits and vegetables at the fortification level of 0.1 μg/g were 75.0-91.8% for BRP, 70.2-88.9% for DDVP, and 77.3-92.1% for DEP. The detection limits of BRP, DDVP and DEP were 1, 2 and 2 ng/g, respectively.

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Simple and reliable methods using LC/MS have been developed for the determination of the β-agonist ractopamine in swine and cattle tissues. Ractopamine was extracted with ethyl acetate from muscle and liver, and the ethyl acetate layer was evaporated to dryness. The residue was purified by partition with acetonitrile/n-hexane. In the case of fat, ractopamine was extracted and purified by partition with acetonitrile/n-hexane. The resulting acetonitrile solutions were evaporated to dryness. The residue was dissolved in methanol, and subjected to LC/MS. The LC separation was performed on a Wakosil-II 3C18HG column (150×3 mm i.d.) in isocratic mode with 0.05% trifluoroacetic acid-acetonitrile (80 : 20) as a mobile phase at a flow rate of 0.4 mL/min. The MS detection was performed in the selected ion recording (SIR) mode, with detection of the M+H⁺ ion of ractopamine (m/z 302) produced by electrospray ionization (ESI). The mean recoveries of the drug from swine muscle (0.01 μg/g fortified), fat (0.01 μg/g fortified) and liver (0.04 μg/g fortified) were 99.7%, 99.5% and 100.8%, and those from cattle samples were 108.3%, 97.0% and 109.4%, respectively. The relative standard deviations (RSDs) ranged from 0.1% to 9.5%. The limit of quantification (LOQ) of the drug was 1 ng/g.

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A simplified method for the determination of forchlorfenuron in agricultural products by HPLC with UV detection was investigated. A chopped sample homogenate from agricultural products was extracted with acetone. The extract was filtrated and concentrated. The residues was loaded onto a Chem Elut column and extracted with ethyl acetate. The crude extract was purified on Oasis HLB and Bond Elut PSA mini-columns using a mixture of methanol and ethyl acetate. Forchlorfenuron was analyzed by HPLC with UV detection (263 nm). HPLC separation was performed on an ODS column with methanol-water as the mobile phase. Recoveries of forchlorfenuron from several agricultural products fortified at the level of 0.1 μg/g were in the range of 87.6-99.5%. The limit of detection (S/N=3) was 0.005 μg/g in the sample.

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A simple and rapid multi-residue method was developed for the determination of 28 kinds of veterinary drugs and feed additives (drugs) in muscle of cattle, pig and chicken. The drugs were extracted with acetonitrile-water (95 : 5) in a homogenizer and ultrasonic generator. The extracted solution was poured into an alumina column and the drugs were eluted with acetonitrile-water (90 : 10). The eluate was washed with n-hexane saturated with acetonitrile and then evaporated. The drugs were separated on a Inertsil ODS-3V column (4.6 mm i.d.×250 mm) with a gradient system of 0.1% phosphoric acid-acetonitrile as the mobile phase, with monitoring at 280 and 340 nm. The recoveries of the 26 kinds of drugs were over 60% from the meats fortified at 0.1 μg/g, and the quantification limits of most drugs were 0.01 μg/g. This proposed method was found to be effective and suitable for the screening of the above drugs in meats.

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Puffer fish is prized as a Japanese traditional food and its fin is also used in the cuisine. However, whether the fin is edible or not is determined for convenience from the toxicity of skin, since little information is available about the toxicity of puffer fish fins. In the present study, we examined the toxicity of fins and skin of three toxic species, Takifugu vermicularis, T. snyderi, and T. porphyreus. The toxicity of T. vermicularis fins (<5-52.4 MU/g) was significantly lower than that of skin (<5-1200 MU/g). HPLC analysis showed that tetrodotoxin was a major toxic principle irrespective of the toxicity value in each tissue of T. vermicularis. In the case of T. snyderi and T. porphyreus, the toxicity of fins was at almost the same level as that of the skin. The toxicity (<10-12 MU/g) of caudal fins of T. porphyreus was apparently increased to 16.5-22.0 MU/g by drying. However, the toxin amounts in the dried fins were slightly decreased as compared with those of the non-dried fins. These results demonstrate that puffer fish with toxic skin also have toxic fins.

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