On-line pretreatment and determination of parabens in cosmetic products by combination of flow injection analysis, solid-phase extraction and micellar electrokinetic chromatography.
A convenient and automated method for on-line pretreatment and determination of three parabens (i.e. methyl, ethyl and propyl p-hydroxybenzoate) in cosmetic products is proposed by using flow injection analysis (FIA), solid-phase extraction (SPE) and micellar electrokinetic chromatography (MEKC). An improved split-flow interface is used to couple SPE on C(8)-bonded silica with MEKC separation, which can avoid running buffer contamination and reduce buffer consumption, especially, containing expensive reagents. The analytes are loaded onto a C(8) column at 0.6 mL/min for 60s and eluted with a mixed eluent of 40% (v/v) 10 mmol/L sodium tetraborate buffer (pH 9.3) and 60% (v/v) ethanol at 0.75 mL/min. The MEKC separation is accomplished with a running buffer of 20 mmol/L sodium tetraborate (pH 9.3) containing 100 mmol/L sodium dodecyl sulfate (SDS) at 15 kV. For butyl p-hydroxybenzoate did not be detected in the cosmetic products, it was used as an internal standard (IS) added into the real samples. This FIA-SPE-MEKC method using IS allows the sample separation within 12 min and the sample throughput of five samples per hour with the relative standard deviation (R.S.D.) less than 2.3% (n=5). The limits of detection (LOD) are in the range from 0.07 to 0.1 microg/mL (S/N=3 and n=11). The proposed method has been used to determine three parabens in real cosmetic products satisfactorily.
Han
Fang
F
Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China.
He
You-Zhao
YZ
Yu
Chang-Zhu
CZ
D002623:Chemistry Techniques, Analytical / Q000379:methods* / Q000592:standards; D020374:Chromatography, Micellar Electrokinetic Capillary; D003358:Cosmetics / Q000737:chemistry*; D017022:Flow Injection Analysis; D010226:Parabens / Q000032:analysis*; D011310:Preservatives, Pharmaceutical / Q000032:analysis; D052616:Solid Phase Extraction
D003358:Cosmetics; D010226:Parabens; D011310:Preservatives, Pharmaceutical; C006068:propylparaben