Analytical method for the identification and assay of 12 phthalates in cosmetic products: Application of the ISO 12787 international standard “Cosmetics–Analytical methods–Validation criteria for analytical results using chromatographic techniques”

► We propose a GC/MS method allowing the separation and quantification of 12 phthalates. ► The method was applied to different cosmetic products. ► Validation criteria on each assay were determined according to ISO 12787 standard. ►Results highlight a satisfactory performance of the analytical method proposed. Esters of phthalic acid, more commonly named phthalates, may be present in cosmetic products as ingredients or contaminants. Their presence as contaminant can be due to the manufacturing process, to raw materials used or to the migration of phthalates from packaging when plastic (polyvinyl chloride – PVC) is used. 8 phthalates (DBP, DEHP, BBP, DMEP, DnPP, DiPP, DPP, and DiBP), classified H360 or H361, are forbidden in cosmetics according to the European regulation on cosmetics 1223/2009. A GC/MS method was developed for the assay of 12 phthalates in cosmetics, including the 8 phthalates regulated. Analyses are carried out on a GC/MS system with electron impact ionization mode (EI). The separation of phthalates is obtained on a cross-linked 5%-phenyl/95%-dimethylpolysiloxane capillary column 30m×0.25mm (i.d.)×0.25mm film thickness using a temperature gradient. Phthalate quantification is performed by external calibration using an internal standard. Validation elements obtained on standard solutions, highlight a satisfactory system conformity (resolution>1.5), a common quantification limit at 0.25ng injected, an acceptable linearity between 0.5μgmL−1 and 5.0μgmL−1 as well as a precision and an accuracy in agreement with in-house specifications. Cosmetic samples ready for analytical injection are analyzed after a dilution in ethanol whereas more complex cosmetic matrices, like milks and creams, are assayed after a liquid/liquid extraction using ter-butyl methyl ether (TBME). Depending on the type of cosmetics analyzed, the common limits of quantification for the 12 phthalates were set at 0.5 or 2.5μgg−1. All samples were assayed using the analytical approach described in the ISO 12787 international standard “Cosmetics–Analytical methods–Validation criteria for analytical results using chromatographic techniques”. This analytical protocol is particularly adapted when it is not possible to make reconstituted sample matrices.