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°C, 20
min) were severe. In this study, an improved pre-column derivatization with 4-(N,N-dimethylaminosulfonyl)-7-(N-chloro-formylmethyl-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 (r2)
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).