Study On The Method For Determination Of Total Phthalates In Cosmetics And Its Application

Phthalates(PAEs)is the most widely used plasticizer with the highest yield.Many researches indicated that PAEs could damage the reproductive,endocrine and respiratory systems,and might interfere with the central nervous system development for infants and toddlers.The significant hazards of PAEs have aroused tremendous attention of government and international organizations,several PAEs are classified as priority hazardous substances by relevant organizations.Nevertheless,it is reported frequently that PAEs are still detected from cosmetics.Cosmetics have become a necessity in our daily life.The long term usage of cosmetics containing PAEs would cause irreparable harm to human body.In order to guarantee products safety according to regulations,the development of reliable analytical methods for the assay of PAEs in cosmetics is essential.The aim of this study is to develop a simple and low organic-solvent-consuming method based on phase-transfer catalyst-assisted hydrolysis(PTC-AH)and liquid phase microextraction(LPME)followed by high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS)for the determination of total phthalates in cosmetics and investigate the possibility of coupling LPME method to capillary electrophoresis(CE)system.(1)This study was developed a PTC-assisted hydrolysis in combination with LPME method for the rapidly assay of total phthalates in cosmetics.The most difficult task was to achieve an effective purification effect on coloured semisolid and solid cosmetics.With this objective,experiments were designed and performed according to the following steps.Firstly,PAEs in cosmetics were extracted with non-polar solvent to remove the water-soluble ingredients in the cosmetics matrix.Then the PAEs in extractant were hydrolyzed and formed an common water-soluble product(Phthalic acid,PA).A clear stratification was formed by application of high concentration of KOH in hydrolysate.Meanwhile,the non-polar distractions contained in extractant and middle layers were eliminated completely with these two layers from the three-phases hydrolysate.Finally,the common product of PAEs was enriched by using LPME technique before HPLC-MS/MS analysis.After parameters affecting the hydrolysis efficiency of PAEs were examined,the analytical method was validated under the optimal selected conditions.The linearity obtainedfor each of the calibration curves were satisfactory with correlation coefficients(r)greater than 0.9992.No obvious matrix effect existed in the cosmetics when internal standard method was adopted.The detection limit was 5.1 μmol kg-1(PA),and the quantification limit was 9.2μmol kg-1(PA).The recoveries obtained were in the range of 84.4~102%,with RSDs equal to or lower than 10%.Finally,the validated method was applied to fifty-seven commercial real samples.The total content of phthalates was generally higher in nail polish and perfume samples,the content were up to 10 mmol kg-1 in some of these samples.The total content in skin-care products and powder-based cosmetics were lower than 83.0 μmol kg-1.Phthalates were found in 81.8%(9:11)oily cosmetics,highlighting the total content were up to 5 mmol kg-1 in two brow pencils.(2)This research explored a method of LPME combined with ASEI-Sweeping by using reversed-phase dispersive liquid-liquid microextraction(RP-DLLME).Parameters including the electrolyte content of sample,the plunger length and the injection conditions that affecting the hydrolysis efficiency of PAEs were optimized and the following general conclusions can be drawn.Firstly,the electrophoretic mobility of the analyte(PA)was suppressed by the presence of strong electrolytes in sample,and the electrokinetic injection stability was improved by adding a small amount of weak electrolyte in sample.Secondly,the contribution of the pure water plunger is to provide a high electric field at the inlet,and improve the initial speed of analyte,the presence of phosphoric plunger had little effect on the enhancement of sensitivity.Thirdly,the pressure-assisted electrokinetic injection(PAEKI)method could availably raise the injection efficiency for the sample without electrolytes and reduce the injection amount of the analyte for sample contains sodium borate.