Sodium dodecyl sulfate sensitized switchable solvent liquid‐phase microextraction for the preconcentration of protoberberine alkaloids in Rhizoma coptidis

Abstract

A sodium dodecyl sulfate sensitized switchable solvent liquid-phase microextraction method was developed and applied to the preconcentration of active alkaloids in Rhizoma coptidis followed by high performance liquid chromatography determination. Before extraction, nonionic triethylamine was converted to its cationic form in the presence of carbon dioxide. Then, the ionic solvent carrying target analytes was once more reverted to its nonionic form by adding sodium hydroxide, as well as phase separation and analytes enrichment were realized simultaneously. Several parameters affecting the approach, such as concentration of sodium dodecyl sulfate, extraction solvent volume, sodium hydroxide concentration, sample phase pH, injection solvent type, and extraction time, were investigated and optimized. The possible microextraction mechanism of double micelle supramolecular inclusion was explored. Under the optimum conditions, the enrichment factors of four protoberberine alkaloids were from 101.8 to 152.0. The linear ranges (with r ≥ 0.990) were 0.032-4.23, 0.031-4.33, 0.0026-10.04, and 0.0013-4.13 μg/mL for epiberberine, coptisine, palmatine, and berberine, respectively. The detection limits were in the range of 0.16-0.32 ng/mL. Satisfactory accuracies (recoveries 98.8-104.6%) and precisions (RSDs 1.9-10.9%) were also obtained. The results showed that the approach is rapid, effective, eco-friendly, and easy-to-handle for the enrichment and detection of active alkaloids in Rhizoma coptidis.

A comprehensive review on recent developments and future perspectives of switchable solvents and their applications in sample preparation techniques

“…169 The protoberberine alkaloids in Rhizoma coptidis were extracted using an SDS-sensitized SHS-LLME, and then their concentration was determined using HPLC-DAD. 170 The measurement of nitrazepam in human urine was combined with differential pulse voltammetry and a pH-assisted SHS-LLME method. 171 Prior to HPLC-UV analysis, a surfactant-mediated method utilizing SHSs was suggested for the extraction of three Sudan dyes from solid food samples (such as salmon and spices).…”

Comparison of three‐phase hollow fiber liquid‐phase microextraction based on reverse micelle with conventional two‐phase hollow fiber liquid‐phase microextraction and their applications for analysis of cinnamic acids in traditional Chinese medicines

“…Surfactants are amphiphilic compounds containing hydrophobic tail group and polar head group. Some research papers have suggested that surfactants can enhance extraction efficiency in LPME procedure as the extraction‐sensitizer . When the concentration of surfactant in nonpolar solvent is greater than the critical micelle concentration, reverse micelles can be formed by the spontaneous aggregation of surfactants.…”