Application of a fabric phase sorptive extraction-high performance liquid chromatography-photodiode array detection method for the trace determination of methyl paraben, propyl paraben and butyl paraben in cosmetic and environmental samples
A new sample preparation and chromatographic separation method for methyl paraben (MP), propyl paraben (PP) and butyl paraben (BP) in cosmetic and environmental samples has been developed, based on fabric phase sorptive extraction (FPSE) and high performance liquid chromatography-photodiode array (HPLC-PDA) detection. In the proposed method, MP, PP and BP molecules were efficiently retained on a sol–gel Carbowax-20M sorbent-coated FPSE membrane when the matrix pH was adjusted to 5. Subsequently, the extracted analytes were desorbed from the FPSE membrane with methanol prior to chromatographic separation and determinations. The samples were transferred to HPLC vials after filtration with a 0.45 μm porous PTFE filter. Experimental conditions were studied to optimize variables such as pH, adsorption time and desorption solvent. Using the optimal conditions, analytical parameters such as linearity ranges, detection limits, and pre-concentration factors for each of the selected parabens were calculated from experimental data. HPLC analyses of MP, PP and BP were carried out in isocratic elution mode using acetic acid (3%) : acetonitrile : methanol in the ratio 70 : 20 : 10. Limit of detection (LOD) values for MP, PP and BP were calculated as 2.85, 2.98 and 2.75 ng mL−1, respectively. Relative standard deviations (RSDs) were below 3.8% for determinations of model solutions including 100 ng mL−1 of each paraben. Finally, the developed method was applied to cosmetic and environmental samples and quantitative results were obtained in recovery experiments.