In mouthwash and liquid dentifrice, benzoic acid, sodium benzoate or parabens are frequently used as preservatives. Although preservatives are generally analysed by HPLC, confirmation of detected components becomes difficult. Thus, we examined the assays by GC/MS. After ethyl acetate was extracted from a sample solution under acidic condition, moisture content was removed by super-absorbent polymer and the extracted solution was analysed by GC/MS (SCAN Mode). The quantitative characteristics were favourable and identification by indication in MS spectrum was possible. Moreover, analytical operation became more convenient by using super-absorbent polymer. Quantifying preservatives in commercially available products by this method, benzoic acid was detected from two of mouthwash and both of the amounts were 150mg/100g. Sodium benzoate was detected from three of mouthwash and four of liquid dentifrice and the mean values were 231mg/100g and 455mg/g, respectively. In addition, the parabens were detected from three of mouthwash and three of liquid dentifrice and the range of concentration is from 7mg/100g to 190mg/100g. Furthermore, since similar quantitative value is obtained by HPLC analysis, the applicability of this method has been shown.
