title: Using dispersive liquid-liquid microextraction and liquid chromatography for determination of guaifenesin enantiomers in human urine.
abstract: A simple, rapid, and efficient method, dispersive liquid-liquid microextraction (DLLME) coupled with high-performance liquid chromatography-fluorescence detector, has been developed for the determination of guaifenesin (GUA) enantiomers in human urine samples after an oral dose administration of its syrup formulation. Urine samples were collected during the time intervals 0-2, 2-4, and 4-6 h and concentration and ratio of two enantiomers was determined. The ratio of R-(-) to S-(+) enantiomer concentrations in urine showed an increase with time, with R/S ratios of 0.66 at 2 h and 2.23 at 6 h. For microextraction process, a mixture of extraction solvent (dichloromethane, 100 μL) and dispersive solvent (THF, 1 mL) was rapidly injected into 5.0 mL diluted urine sample for the formation of cloudy solution and extraction of enantiomers into the fine droplets of CH(2)Cl(2). After optimization of HPLC enantioselective conditions, some important parameters, such as the kind and volume of extraction and dispersive solvents, extraction time, temperature, pH, and salt effect were optimized for dispersive liquid-liquid microextraction process. Under the optimum extraction condition, the method yields a linear calibration curve in the concentration range from 10 to 2000 ng/mL for target analytes. LOD was 3.00 ng/mL for both of the enantiomers.
authors.affiliation: Department of Chemistry, Faculty of Science, Urmia University, Urmia, Iran.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Hatami
authors.forename: Khalil
authors.initials: K
authors.lastname: Farhadi
authors.forename: Assem
authors.initials: A
authors.lastname: Abdollahpour
mesh_terms: D000328:Adult; D002851:Chromatography, High Pressure Liquid; D006140:Guaifenesin / Q000031:analogs & derivatives / Q000032:analysis* / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D059627:Liquid Phase Microextraction; D008297:Male; D008968:Molecular Conformation; D012016:Reference Values; D012965:Sodium Chloride / Q000737:chemistry; D013237:Stereoisomerism; D013696:Temperature; D016482:Urinalysis; D014556:Urine / Q000737:chemistry*
chemical_list: D012965:Sodium Chloride; D006140:Guaifenesin