Bisphenol A (BPA) values were compared in plasma of hemodialysis patients and in recycling solvents using LC/MS, LC/electrochemical detector (ECD), and enzyme linked immunosorbent assay (ELISA). BPA values in the plasma and the solvent were 0-8.4 ng/ml and 0-0.8 ng/ml for LC/ECD, 0-4.9 ng/ml and 0-0.8 ng/ml for LC/MS, and 0-15.5 ng/ml and 0-3.1 ng/ml for ELISA, respectively. There was no significant difference among BPA values both in the plasma and the solvents using three methods. Single correlation coefficients between LC/ECD and LC/MS, LC/ECD and ELISA, and LC/MS and ELISA were, respectively, 0.373 (p < 0.002), 0.347 (p < 0.002), and 0.945 (p < 0.001) in the plasma (n = 68-109) and 0.916 (p < 0.001), 0.431 (p > 0.05), and 0.332 (p > 0.05) in the solvents (n = 19). An unknown substance present in the plasma of patients but not healthy volunteers influenced the LC/ECD values of plasma repeated freezing and thawing. The results indicate that LC/MS and ELISA are appropriate for BPA analysis in plasma and both LC/MS and LC/ECD in the recycling solvents and handling with plasma before analysis is important to the analysis of BPA in patients' plasma using LC/ECD.

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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 o$cial method were applied to the specific detection of plant DNA. A primer pair of Plant01-5῎ and Plant01-3῎ (amplicon size; 161 bp) was the most suitable for the specific detection of plant DNA. M-PCR was performed to detect the specific DNAs of allergenic substances using four primer pairs, a pair of Plant01-5῎ and Plant01-3῎, and three pairs for allergenic components described in the Japanese o$cial method. The four specific PCR bands were simultaneously amplified from genomic DNAs of allergenic substances. The proposed method is simple, rapid and inexpensive.

A nested PCR method was developed for the detection of DNAs extracted from allergenic substances (here, wheat) in food. Because of DNA fragmentation, detection of wheat-specific DNA extracted from food, such as retort pouch food, is very di$cult. Therefore, to improve the sensitivity of detection, a nested PCR primer pair (Wtr01NE2-5῎ and Wtr10NE5-3῎: amplicon size 97 bp) was newly designed within the region of the PCR products amplified by the o$cial Japanese primer pair (Wtr01-5῎ and Wtr10-3῎; amplicon size 141 bp) for wheat. Genomic DNAs of seven kinds of commercial processed foods containing wheat, wheat flour and three kinds of wheat flours pressure-heated at 100, 121 and 131̮ were extracted with a commercial ionexchange type kit by modifying the Japanese o$cial method. The nested PCR method involved two PCR procedures. First, PCR was performed by varying both the PCR reagents and cycling conditions of the Japanese o$cial method. Second, PCR was performed using the first PCR products diluted 200-fold with TE bu#er. The Japanese o$cial method enabled detection of only four of the seven kinds of foods and three of the four kinds of flours (one sample was just a trace), while the nested PCR method detected all seven foods and all four flours. Investigation of the detectability of the four kinds of wheat flours depending on the size of the amplified fragment using five primer pairs showed that its size must be kept to less than approximately 100 bp. The nested PCR method significantly improved the sensitivity of detection of wheat-specific DNA.

A simultaneous method using iontrap gas chromatography/mass spectrometry (GC/MS) was developed for the determination of pesticide residues in four processed foods (frozen Chinese dumpling, eel kabayaki, corned beef and retort curry). Pesticide residues were extracted from samples with ethyl acetateῌcyclohexane (1 : 1) in the presence of anhydrous sodium sulfate. The extract was concentrated and the residue was dissolved in n-hexane. The lipids in the extract were removed by acetonitrileῌn-hexane partitioning, following which the acetonitrile layer was cleaned up using a C 18 mini-cartridge column and a graphite carbon/PSA silica (GCB/PSA) mini-cartridge column. The limits of quantification of compounds in 4 processed foods were below 0.01 mg/g. The recoveries of 292 compounds spiked at 0.1 mg/g in 4 kinds of processed foods, and 210 to 262 pesticides showed acceptable recoveries of 70ῌ120̮ with low repeatability (15̮) and intermediate precision (20̮) only at the 0.1 mg/g spiked level. This method is expected to be useful for multi-residue analysis of pesticide residues in processed foods manufactured using livestock and seafoods as the main raw materials.