Girard reagent purification coupled with hollow-fiber-based stirring liquid microextraction followed by HPLC with diode array detection for determination of naphthoquinones in Qing Long Yi

Abstract

Naphthoquinones all with carbonyl groups may react with the Girard reagent (GR) to form a water-soluble substance called hydrazone and then these denatured naphthoquinones can recover lipid solubility transferred to the layer of organic solvents under acidic conditions, which differ from other compositions. Making use of this property, GR purification coupled with hollow-fiber-based stirring liquid microextraction (HF-SLME) has been developed as a preconcentration technique for the purification of naphthoquinones in QLY. Related parameters affecting both structural conversion and dispersive extraction procedures such as reaction time, amount of the catalyst, the type of the extraction solvent, pH in the extraction course, extraction time and stirring speed were investigated and optimized. The extracts were subsequently analyzed by high performance liquid chromatography coupled with a diode array detector (HPLC-DAD). The LODs ranged from 0.028 to 0.043 μg mL⁻¹. The linear regressions were acquired with r > 0.9995. The recovery studies for the quantified compounds were observed in the range of 79.19–102.02%. The RSDs were less than 3.46%. The experimental results indicated that the novel preconcentration technique was crucial to improve the resolution of analyte peaks and reduce the interference from background components.