Taro Kawamura

市販冷凍野菜中からのプラスチック酸化防止剤トリス(2,4-ジ-t-ブチルフェニル)ホスファイト(Irgafos 168)およびその酸化物の検出

Two peaks, A and B, detected in chromatograms of commercial frozen vegetable extracts during analysis of organophosphorus pesticide residues by GC-FPD, were identified as tris(2,4-ditert-butylphenyl)phosphite (Irgafos 168) and Irgafos 168 oxide, respectively, from their mass spectra. Irgafos 168 is used as an antioxidant in plastics, and there has been no report of its detection in foods. We analyzed Irgafos 168 and its oxide in 38 samples of commercial frozen vegetables, and they were detected from 4 samples (0.02-0.80 microgram/g as total amount of Irgafos 168 and its oxide).

Detection of Tolclofos-methyl and Its Decomposition Product (2, 6-Dichloro p-cresol) in Phenolic-Smelling Tomatoes

We investigated the cause of a phenolic smell in tomatoes. But this time prothiofos and 2, 4-dichlorophenol were not detected in the tomatoes. When we analyzed pesticide residues in soil of the tomato field, we detected tolclofos-methyl in the range of 0.02-2.2μg/g and 2, 6-dichloro-p-cresol, a decomposition product of tolclofos-methyl, in the range of 0.03-0.15μg/g. We also detected tolclofos-methyl and 2, 6-dichloro-p-cresol, each in the range of 0.01-0.02μg/g, in the tomatoes. 2, 6-Dichloro-p-cresol has a phenolic smell. We concluded that 2, 6-dichloro-p-cresol accounted for the phenolic smell, at least in part.

Determination of Residual Chlorine in Foods by Head Space Gas Chromatography

An analytical method was developed for quantitative determination of residual chlorine in foods using head space gas chromatography.The principles of the proposed method are as follows. Phosphate buffer solution of pH 7.0 and potassium cyanide solution were placed in a vessel for head space analysis, a sample was added, and the resultant mixture was left standing in the vessel (covered with a lid) for 30 minutes. Cyanogen chloride formed therein was determined by ECD-GC. The values of residual chlorine in tap water measured by the present method were compared with those obtained by the o-tolidine colorimetric method. The respective values were quite consistent. The determination limit was 0.1μg/g.Analysis of 67 specimens of vegetables and processed fish and shellfish products available in the market revealed 14.0μg/g and 11.6μg/g of residual chlorine in two specimens of soybean sprouts.

Determination of Minute Amounts of Arsenic by means of Detector Tubes

従来行われているヒ素の微量定量法としてのGutzeit法は定性法としては十分であるが,定量法としては,なお若干の難点がある。すなわち,ロ紙の幅,表裏,ガラス管への挿入状態等によって着色層の長さが異なり,かつその先端が明瞭でないこと等のためにその測定値の精度が低いことである。著者らはGutzeit法を改良する目的で着色装置としてロ紙の代りに検知管を用いることにより,これらの欠点を克服しようとした。まずヒ化水素により鋭敏に着色する試薬の探索を行った結果,塩化金を採用し,この一定量をシリカゲル粒に吸着,乾燥し,鋭敏に白色から濃紫青色に変わる検知剤をえ,これを細いガラス管に一定量充填して検知管を作製した。次にGutzeit法の試験装置のうち,臭化第二水銀紙細管の代りに検知管を用い,ヒ化水素を40分間発生させ,生じる検知管の着色層の長さから微量のヒ素の含有量を求めた。その結果はAs2O3として0.5～40γのヒ素を精度よく本法により定量できた。