Development and evaluation of semi-destructive, ultrasound assisted extraction method followed by gas chromatography coupled to mass spectrometry enabling discrimination of red lipstick samples

Abstract

In this study, the effective and robust semi-destructive ultrasound assisted extraction (UAE) method followed by gas chromatography coupled to mass spectrometry (GC–MS) method used for analysis of red lipsticks samples was developed, optimized and evaluated. 43 red lipsticks of a very similar hue representing of 21 different manufacturers were investigated. The red lipsticks (approximately 0.05 mg) were applied on a disc (of ø 2 mm) placed on specially designed stand printed with a 3D printer. In order to optimize the main factors affecting extraction process, Doehlert experimental design with response surface methodology was applied. The optimal for all analysed lipsticks UAE extraction conditions were: 21 min – time, 35 °C – temperature of the ultrasonic bath, and the 100 μL of extraction mixture of acetonitrile, methanol and acetone (50:30:20, v/v/v). The developed, qualitative UAE/GC–MS method was evaluated and then successfully used for the differentiation of 43 red lipsticks. In this case, the two approaches were utilized: the visual inspection of chromatograms and the likelihood ratio model. The results confirmed that the proposed method has a great potential in lipsticks differentiation and after adaptation to real samples it seems to be a good alternative to the methods routinely used in forensic science investigations.