Sensitive determination of 1- and 2-naphthol in human plasma by HPLC-fluorescence detection with 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride as a labeling reagent

Abstract

A sensitive HPLC-fluorescence (FL) method with FL-labeling reagent for simultaneous determination of 1- and 2-naphthol was developed. The FL-labeling reaction of naphthols with 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride (DIB-Cl) was completed in 20 min at 40°C. The separation of DIB derivatives was achieved with an ODS column and isocratic elution. The LODs of 1- and 2-naphthol were 16 fmol and 14 fmol/injection, respectively, which were 5-fold and 14-fold lower than those obtained by HPLC-FL method using the native FL of naphthols. The DIB-naphthol derivatives were stable for at least 24 h even when they were placed at room temperature. The proposed method was applied to the measurement of 1- and 2-naphthol in human plasma with sufficient accuracy (90.8–109%) and precision (< 6.3%).