保存料(デヒドロ酢酸, ソルビン酸, 安息香酸)のガスクロマトグラフィーにおける内部標準物質としてのp-トルイル酸の選択

抄録

The"Standard Methods of Analysis for Hygienic Chemists"authorized by the Pharmaceutical Society of Japan (published in 1973) prescribe the use of acetanilide as an internal standard for the gas chromatographic determination of dehydroacetic acid, sorbic acid, benzoic acid, and esters of p-hydroxybenzoate, using the FID gas chromatograph fitted with columns packed with 5% DEGS+1% H₃PO₄. When only the three preservatives (sorbic acid, dehydroacetic acid, and benzoic acid) have to be examined in one sample (such cases are often encountered), the retention time of acetanilide seems to be too long compared with those of the three preservatives. Moreover, the broad peak of acetanilide might make it impossible to carry out an accurate determination of the three preservatives. Accordingly, replacement of acetanilide with another suitable internal standard was examined and p-toluic acid was finally chosen as the new internal standard. The use of p-toluic acid increases the measurement accuracy of the three preservatives by three times.