Simultaneous Determination of 2,5-Hexanedione, Phenol and o-Cresol in Urine Samples by HPLC with Dispersive Liquid Phase Micro-extraction

A method of HPLC with dispersive liquid phase micro-extraction was proposed for the simultaneous determination of 2,5-hexanedione, phenol and o-cresol in urine samples. The optimized conditions found were as follows: ① derivative reagent: 2,4-dinitrophenylhydrazine; ② time of reaction: 20 min; ③ temperature of reaction: 70 ℃; ④ amount of chloroform (extractant): 0.3 mL; ⑤ time of extraction: 10 min. A C18 chromatographic column was used as stationary phase with mixtures of methanol and water with different mixing ratios as mobile phase in the gradient elution. A UV detector was used. Linear relationship between the peak area and the mass concentration of 2,5-hexanedione, phenol and o-cresol kept in definite ranges. Detection limits (3S/N) ranged from 0.3 to 0.7 μg·L-1. The recovery rates measured by standard addition method were in the range of 89.1%-104%, and RSD (n=7) was in the range of 3.0%-4.6%.