Improvement in the identification and quantification of UV filters and additives in sunscreen cosmetic creams by gas chromatography/mass spectrometry through three-way calibration techniques

Abstract

The simultaneous determination of 2,6-di-tert-butyl-4-methyl-phenol (BHT), benzophenone (BP), benzophenone-3 (BP3) and diisobutyl phthalate (DiBP) in seven sunscreen creams was carried out by gas chromatography/mass spectrometry (GC/MS) using DiBP-d4 as internal standard. The content of BP3, which is a UV filter, must not exceed 6% (w/w) in cosmetic products according to Regulation (EU) 2017/238 and the use of DiBP in cosmetic products shall be prohibited according to Regulation (EC) No 1223/2009.

The conclusions obtained with the univariate standard methodology in the identification of the analytes contained in the creams were wrong. However, a calibration based on PARAFAC or PARAFAC2 decompositions, where the samples of the prediction set were projected on the model obtained previously with the calibration set, enabled the unequivocal identification and quantification of the analytes even in the presence of interferents not considered in the calibration model. The PARAFAC2 decomposition was used to overcome the shifts in the retention time of BP and BP3. These three-way calibration techniques are needed to avoid false negative results. The method had not proportional or constant bias.

The presence of BHT was detected in the seven sunscreen creams analysed at an amount of 6.48 10−2%, 8.53 10−2%, 1.70 10−4%, 1.11 10−4%, 2.51 10−3%, 3.20 10−5% and 6.35 10−3%. The concentrations of DiBP found in four creams were 3.49 10−2%, 3.19 10−2%, 3.26 10−2% and 2.51 10−2%. On the other hand, BP was only detected in two of the cosmetic creams analysed at an amount of 7.84 10−3% and 1.04 10−2%. In addition, BP3 was detected in six of the creams at an amount of 4.73%, 3.49%, 4.94 10−3%, 1.98 10−3%, 6.62 10−1% and 1.73%. Therefore, none of the cosmetic creams contained BP3 in an amount higher than 6%.