title: A solid-phase extraction and size-exclusion liquid chromatographic method for polyethylene glycol 25 p-aminobenzoic acid determination in urine: validation for urinary excretion studies of users of sunscreens.
abstract: No previous publications about percutaneous absorption of polyethylene glycol 25 p-aminobenzoic acid (PEG-25 PABA) have been found in the literature and the expected levels to be found in human urine after sunscreens use are unknown. The method proposed here is suitable to determine PEG-25 PABA in the urine of sunscreens users in order to carry out studies on body accumulation/excretion. It is based on solid-phase extraction (SPE) with size-exclusion liquid chromatography determination. Solid-phase extraction allows the analyte to be retained and subsequently eluted for a clean-up, using a silica-based cartridge. The size-exclusion liquid chromatography of the eluted allows the rest of matrix interferences to be avoided. Fluorescence intensity was measured at lambda(em)=350 nm (lambda(exc)=300 nm). The sensitivity of the proposed method is in the order of 450+/-5 mLng(-1) and the detection limit (3S(y/x)/b) in the measured solutions is in the order of 13 ngmL(-1), that is 2.6 ngmL(-1) in urine samples. The method enables PEG-25 PABA to be determined in both, spiked and unspiked human urine samples. Results obtained for spiked human urine samples (11-100 ngmL(-1)) demonstrated the accuracy of the method. The mean relative standard deviation of the results was in the order of 3-10%. Three volunteers applied a sunscreen lotion containing a 8% PEG-25 PABA sunscreen cream and their urinary excretion was controlled from the moment of application until the excreted amounts were no longer detectable.
authors.affiliation: Departamento de Química Analítica, Universitat de València, 50 Doctor Moliner St., 46100-Burjassot, Valencia, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Balaguer
authors.forename: A
authors.initials: A
authors.lastname: Chisvert
authors.forename: A
authors.initials: A
authors.lastname: Salvador
authors.forename: M
authors.initials: M
authors.lastname: Herraez
authors.forename: O
authors.initials: O
authors.lastname: Diez
mesh_terms: D010129:4-Aminobenzoic Acid / Q000652:urine*; D002850:Chromatography, Gel / Q000379:methods*; D006801:Humans; D011092:Polyethylene Glycols / Q000032:analysis*; D015203:Reproducibility of Results; D013050:Spectrometry, Fluorescence; D013473:Sunscreening Agents / Q000032:analysis*
chemical_list: D013473:Sunscreening Agents; D011092:Polyethylene Glycols; D010129:4-Aminobenzoic Acid