Improved Method for Determination of Raspberry Ketone in Fragrance Mist by HPLC-Fluorescence Analysis after Pre-Column Derivatization with 4-(<i>N,N</i>-Dimethylaminosulfonyl)-7-(<i>N</i>-chloroformylmethyl-<i>N</i>-methylamino)-2,1,3-benzoxadiazole

Abstract

Raspberry ketone {RK, 4-(4-hydroxyphenyl)butan-2-one} is structurally resembles 4-(4-hydroxyphenyl)-2-butanol, which causes leukoderma on consumers’ skin. Therefore, it is important to measure in cosmetics for quality assessment. Very recently, an HPLC-fluorescence method for determination of RK in a fragrance mist by pre-column derivatization with 4-hydrazino-7-nitro-2,1,3-benzoxadiazole hydrazine was established. However, the derivatization conditions (80 &deg;C , 20 min) were severe. In this study, an improved pre-column derivatization with 4-( N , N -dimethylaminosulfonyl)-7-( N -chloro-formyl methyl- N -methylamino)-2,1,3-benzoxadiazole (DBD-COCl) is presented by HPLC-fluorescence method for determination of RK. The DBD-CO-RK derivative was eluted from a reversed-phase ODS column, and detected with excitation at 440 nm and emission at 543 nm. Derivatization was performed at room temperature for 3 min. The retention time of DBD-CO-RK derivative was 16.8 min. The standard curve was linear in the range of 0.05 to 2.5 μg/mL , with a correlation coefficient ( r 2 ) value of 0.9988. The lower limit of detection was 0.01 μg/mL (absolute amount of 0.3 pmol). The coefficients of variation were less than 10.0%. The content of RK in fragrance mist (1.00 mL) was 1.20 ± 0.08 mg ( range, 1.10 to 1.31 mg, n = 5). Recovery tests were satisfactory (91.8 ± 5.4%; range, 84.2 to 98.2%, n = 5).