凝胶渗透色谱净化-气相色谱-串联质谱法同时测定不同配方体系化妆品中7种二甲基环硅氧烷

Simultaneous determination of seven dimethylcyclosiloxanes in cosmetics of different formulation systems by gel permeation chromatography purification-gas chromatography-tandem mass spectrometry

鉴于当前化妆品中二甲基环硅氧烷的添加乱象,以及关于二甲基环硅氧烷在化妆品中安全风险评价的研究也未有实质性进展,因此建立适合不同配方体系化妆品中二甲基环硅氧烷的测定方法具有一定的理论和现实意义。基于此,建立了凝胶渗透色谱净化结合气相色谱-串联质谱测定不同配方体系化妆品中7种二甲基环硅氧烷的方法。方法采用乙酸乙酯-环己烷(1∶1,v/v)提取,凝胶渗透色谱净化,通过DB-5ms色谱柱(30.0 m×0.25 mm×0.25μm)分离和气相色谱-串联质谱选择反应监测(SRM)模式进行确证和检测,以正十六烷为内标物内标法定量。分别对内标物、提取溶剂和净化方式的选择进行了优化。在最终确立的条件下,7种二甲基环硅氧烷在0.05~1.0 mg/L范围内线性良好,相关系数为0.994~0.998;方法的检出限(LOD,S/N=3)和定量限(LOQ,S/N=10)分别为0.04~0.08 mg/kg和0.12~0.24 mg/kg;针对不同配方体系的化妆品基质,进行了低、中、高3个添加水平的加标回收试验,目标物的加标回收率为85.3%~108.8%,相对标准偏差(RSD)为3.1%~9.4%。该方法操作简便,灵敏度高,重复性好,能够满足不同配方体系化妆品中7种二甲基环硅氧烷的测定要求。采用所建立的方法对市面上的化妆品进行检测,八甲基环四硅氧烷(D4)和十甲基环五硅氧烷(D5)均有不同程度的检出。该方法的建立将为我国化妆品中二甲基环硅氧烷的质量监督检查提供技术依据,有利于保障化妆品的安全,同时也为后续化妆品中二甲基环硅氧烷的健康安全风险评价提供了技术支撑。

At present,the addition of dimethylcyclosiloxanes(DMCs)in cosmetics is being debated and no substantial progress has been made in their safety risk assessment because of the lack of a suitable analytical method.Therefore,it is of theoretical and practical significance to establish a method suitable for the determination of DMCs in cosmetics with different formulation systems.Accordingly,a method based on gel permeation chromatography(GPC)purification combined with gas chromatography-tandem mass spectrometry(GC-MS/MS)was developed for the determination of seven DMCs in cosmetics.The cosmetic samples were extracted by ethyl acetate-cyclohexane(1∶1,v/v),purified by gel permeation chromatography,separated on a DB-5ms column(30.0 m×0.25 mm×0.25μm),confirmed and detected by gas chromatography-tandem mass spectrometry in the selected reaction monitoring(SRM)mode,and quantified by the internal standard method with n-hexadecane as the internal standard.Experiments were carried out using n-tetradecane,n-hexadecane,and n-octadecane as the internal standards,and based on the retention time in GPC and GC,n-hexadecane was found to be the suitable choice for further analyses.The extraction efficiency for the target compounds was tested in different solvents such as methanol,n-hexane,acetonitrile,ethyl acetate,and ethyl acetate-cyclohexane(1∶1,v/v).Given the high recovery,ethyl acetate-cyclohexane(1∶1,v/v)was selected as the extraction solvent for analyses.Among the three purification methods(analysis without purification,solid-phase extraction(SPE),and GPC purification),GPC was selected as the best method because of the minimal matrix interference to the target compounds.Under the optimized conditions,the seven DMCs showed good linearities in the range of 0.05-1.0 mg/L.The correlation coefficients(r)were 0.994-0.998,which were greater than the required of the specification(r≥0.990).The limits of detection(LODs,S/N=3)were 0.04-0.08 mg/kg,and the limits of quantification(LOQs,S/N=3)were 0.12-0.24 mg/kg.According to the cosmetic matrix in different formulation systems,standard addition recovery tests at three levels of low,medium,and high were carried out.The average recovery rates of the targets were 85.3%-108.8%.The relative standard deviations(RSDs,n=6)were 3.1%-9.4%.The established method was also employed for the analysis of cosmetics in the market,and octamethylcyclotetrasiloxane(D4)and decamethylcyclopentasiloxane(D5)were detected at various levels in the cosmetics.The method established in this study has the advantages of operational simplicity,high sensitivity,and good reproducibility,and it allows for the determination of seven DMCs in cosmetics with different formulation systems.The establishment of this method provides a basis for the quality supervision and inspection of DMCs in cosmetics in China,in addition to providing technical support for follow-up health and safety evaluation.