Hollow Fiber Supported Liquid Membrane Extraction Combined with HPLC-UV for Simultaneous Preconcentration and Determination of Urinary Hippuric Acid and Mandelic Acid

Abstract

This work describes a new extraction method with hollow-fiber liquid-phase microextraction based on facilitated pH gradient transport for analyzing hippuric acid and mandelic acid in aqueous samples. The factors affecting the metabolites extraction were optimized as follows: the volume of sample solution was 10 mL with pH 2 containing 0.5 mol·L−1 sodium chloride, liquid membrane containing 1-octanol with 20% (w/v) tributyl phosphate as the carrier, the time of extraction was 150 min, and stirring rate was 500 rpm. The organic phase immobilized in the pores of a hollow fiber was back-extracted into 24 µL of a solution containing sodium carbonate with pH 11, which was placed inside the lumen of the fiber. Under optimized conditions, the high enrichment factors of 172 and 195 folds, detection limit of 0.007 and 0.009 µg·mL−1 were obtained. The relative standard deviation (RSD) (%) values for intra- and inter-day precisions were calculated at 2.5%–8.2% and 4.1%–10.7%, respectively. The proposed method was successfully applied to the analysis of these metabolites in real urine samples. The results indicated that hollow-fiber liquid-phase microextraction (HF-LPME) based on facilitated pH gradient transport can be used as a sensitive and effective method for the determination of mandelic acid and hippuric acid in urine specimens.

Ion‐pair‐based hollow‐fiber liquid‐phase microextraction combined with high‐performance liquid chromatography for the simultaneous determination of urinary benzene, toluene, and styrene metabolites

“…Thus, it is possible to actively transport the anions from the donor sample into the acceptor phase by using a cationic carrier in membrane solvent extraction. According to the results of our previous work , 1‐octanol was used as organic phase. Aliquat‐336 was selected as the cationic carrier and dissolved in the membrane organic solvent.…”

“…HF‐LPME is a non‐exhaustive extraction technique in which the analytes are partitioned between three phases, i.e. the aqueous donor matrix, the organic solvent, and the aqueous acceptor phase, until equilibrium is established . At the extraction times longer than 60 min, the enrichment factor reduced.…”

“…Hollow‐fiber‐based liquid‐phase microextraction (HF‐LPME) has been used as a new technique for pretreatment of various compounds in different biological samples. it can meet most of the demands of a good sample preparation technique, including low consumption of organic toxic solvents (microliter volumes), cheapness, quickness, easy operation, no carryover due to the single use of the fiber, high pre‐concentration, and automation . Compared to hydrophobic analytes, hydrophilic and polar ones are not easily extracted from the donor aqueous phase into the organic phase.…”

“…In simple carrier transport, the carriers such as tri‐ n ‐octyl‐phosphine oxide (TOPO) and tributyl phosphate (TBP) as neutral carriers form lipophilic complexes with the analytes in the donor phase and diffuse to the receiving phase, where the compound is changed to a non‐extractable form . In our previous studies, the applicability of the simple carrier mediated transport HF‐LPME for extraction of MA, HA and, ttMA is investigated . In coupled counter‐transport, ionic carriers have been used to provide facilitated transport by ion‐pairing mechanism in which at the interface between the donor phase and liquid membrane, the ionic carrier and analyte form a neutral ion‐pair complex.…”

Development of Simultaneous Analysis of Thirteen Bioactive Compounds in So-Cheong-Ryong-Tang Using UPLC-DAD

“…Second, the volume (50 and 100 mL) of the extraction solvent was investigated. Finally, extraction methods using ultrasonic or reflux were investigated [ 20 – 22 ].…”