A rapid and simultaneous method for the determination of naphthol isomers in urine by molecular complex-based dispersive liquid–liquid microextraction combined with high-performance liquid chromatography

Abstract

A rapid and simultaneous method for the determination of naphthol isomers in human urine has been developed and validated by using molecular complex-based dispersive liquid–liquid microextraction followed by high-performance liquid chromatography. This method worked by the formation of hydrogen bond interaction between the extractant (1-octanol, Lewis base) and the analytes (naphthols, Lewis acid). Experimental parameters, including the type and volume of the extractant and disperser, pH, addition of salt, extraction time, were examined and optimized. Additionally, the proposed method was applied to human urine samples collected from six volunteer donors of the chemical laboratory. Under the optimum conditions, average recovery rates for the real samples varied from 78.5 to 98.2%, with the relative standard deviations less than 7.6%. The method offered excellent linearity over a range of 5–5000 ng/mL with correlation coefficient (r < 0.999). The detection limit (S/N = 3) was 0.61–0.69 ng/mL. The developed method was successfully applied to the determination of naphthol isomers in human urine. Compared with the previous DLLME methods, the feature of the new procedure lies in simpler sample preparation, higher sensitivity and lower cost of the extraction device. Also, theoretical calculations were conducted to understand the molecular interaction mechanism between 1-octanol and naphthols.