Masatoshi Yamamoto

Determination of isoflavones in soy bean by high-performance liquid chromatography with amperometric detection

Technique de dosage des 4 principales isoflavones (a activite biologique non negligeable) du soja delipide

High-performance liquid chromatographic determination of six p-hydroxybenzoic acid esters in cosmetics using Sep-Pak florisil cartridges for sample pre-treatment.

A rapid and simple method is described for the simultaneous determination of methyl, ethyl, isopropyl, n-propyl, isobutyl and n-butyl p-hydroxybenzoic acid esters (parabens) in cosmetics by high-performance liquid chromatography (HPLC). The method involves a single extraction of parabens with diethyl ether and clean-up on a Sep-Pak Florisil cartridge. Fat-soluble excipients in the diethyl ether extracts are removed through the cartridges with hexane-chloroform (75:25). Parabens are then eluted from the cartridges with hexane-ethyl acetate (70:30) and determined by HPLC on a reversed-phase column with water-methanol (50:50) as the mobile phase using sec.-butylpraben as an internal standard. The method was applied to samples with complicated matrices such as cream, milk lotion, lotion and cleansing foam, and the recoveries were 99.0-102.3% with coefficients of variation of 0.3-1.2%.

Determination of Phenolic Anti-Oxidants in Edible Oil by High-Performance Liquid Chromatography with Amperometric Detector

Abstract A high-performance liquid chromatography (HPLC) with amperometric detection was investigated for the analysis of 2-and 3-tert-butyl-4-hydroxyanisole (BHA), 3,5-di-tert−butyl-4-hydroxytoluene (BHT), and tert−butyl-hydroquinone (TBHQ) in edible oil. The reversed-phase system developed was combined with an amperometric detector, the working electrode of which was made of glassy carbon, in order to compare the sensitivity and selectivity of ultraviolet and fluorometric detection. For the amperometric detection of HPLC, cyclic voltammetry was used to monitor the electrochemical properties of the phenolic antioxidants. A simple isolation procedure, based on the continuous liquid-liquid partition technique, was examined for the extraction and clean up of the antioxidants from edible oil. The recovery rates of BHA, BHT, and TBHQ added salad oil were between 90.2-107.7% in the range of 1-50 ppm of the antioxidants. By the present method, BHA, BHT, and TBHQ were well separated, identified and quantitated w...

Determination of Diethylene Glycol in Toothpaste

ガスクロマトグラフィー (GC) による練り歯磨き中のジエチレングリコール (DEG) の迅速かつ簡易な分析法を開発した。練り歯磨き中のDEGは, 1, 4-ブタンジオールを内標準物質として含有するメタノール溶液で超音波処理により抽出した。メタノール抽出液を遠心, ろ過した後, InertCap 624キャピラリーカラムを用いたGCにより分析した。練り歯磨きにDEGを0.1-1.0%添加した場合の回収率は99.4-103.6%であった。練り歯磨き中のDEGの定量限界は0.05%であった。この方法は他の市販化粧品にも適用することができた。この分析法を用いて, 旅館やホテルで使用される練り歯磨き10検体について分析し, 2検体からDEGを検出した。本分析法が化粧品製造販売業者および輸入販売業者における品質管理に役立つことを期待する。

Migration of Dibutylhydroxytoluene from Plastic Packaging Material into Dried Fishes and Shellfishes

Dibutylhydroxytoluene (BHT) was detected in dried fishes to which it had not been added as a food additive. In order to examine the migration of BHT from the plastic packaging material to the dried fishes, the relationship between the storage conditions (temperature and duration) and the quantity of migration was investigated. Increased quantity of migration was observed at higher temperatures and longer periods of storage.A random survey of foods on the market revealed 2.0-3.6mg/kg of BHT in dry foods and 0.15-1.7μg/cm2 in the plastic wrapping material. BHT was detected more frequently in wrapping with lower gas permeability, namely polyvinilidene chloride, than in other wrapping material.

Contents of Eicosapentaenoic Acid and Docosahexaenoic Acid in “Health Food”

A simple method for the determination of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in “health food” contained EPA by gas liquid chromatography (GC) was developed.A sample of 100mg was methyl-esterified by the boron trifluoride-methanol (BF3-MeOH) method and the product was extracted with hexane containing triphenyl ethylene as an internal standard. The sample solution was determined by GC on a 10% Silar 10C column. Recoveries of EPA and DHA added to oils were in the range of 98.8-107% and 98.8-122%, respectively. The present method was applied to “health food” contained EPA. The results showed thet the quantities of EPA and DHA (mg) per gram of oils and fats of the supplements were 20.3 and 11.4 on average, respectively.Moreover, the fatty acid composition, acid value (AV), peroxide value (POV) and tocopherols (Toc) in the “health food” were investigated. Though the “health food” is easily taken, from the viewpoint of safety, nutritional balance and price, EPA and DHA should be taken in the diet in the form of sardines, mackerels, and so on.