title: 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-1sodium 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-1were 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.
authors.affiliation: Excellence Centre of Occupational Health, Research Center for Health Sciences, School of Public Health, Hamadan University of Medical Sciences, Hamadan 6517838736, Iran. bahrami@umsha.ac.ir.
authors.forename: Abdulrahman
authors.initials: A
authors.lastname: Bahrami
authors.affiliation: Department of Occupational Health, School of Public Health, Arak University of Medical Sciences, Arak 3819693345, Iran. f.ghamari@umsha.ac.ir.
authors.forename: Farhad
authors.initials: F
authors.lastname: Ghamari
authors.affiliation: Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, Tehran 1411713116, Iran. yyamini@modares.ac.ir.
authors.forename: Yadollah
authors.initials: Y
authors.lastname: Yamini
authors.affiliation: Excellence Centre of Occupational Health, Research Center for Health Sciences, School of Public Health, Hamadan University of Medical Sciences, Hamadan 6517838736, Iran. fghorbani@umsha.ac.ir.
authors.forename: Farshid
authors.initials: F
authors.lastname: Ghorbani Shahna
authors.affiliation: Department of Biostatistics and Epidemiology, School of Public Health and Center of Health Research, Hamedan University of Medical Sciences, Hamedan 6517838736, Iran. moghimb@yahoo.com.
authors.forename: Abbas
authors.initials: A
authors.lastname: Moghimbeigi
keywords: HF-LPME; HPLC-UV; facilitated pH gradient transport; hippuric acid; mandelic acid; toluene and ethylbenzene metabolites