Application of micellar electrokinetic capillary chromatography to the discrimination of red lipstick samples

The main aim of this study was to apply capillary electrophoresis (CE) to the discrimination of red lipsticks – the first step towards developing the methodology for forensic purposes. The separation method was optimized using a mixture of eight dyes and micellar electrokinetic capillary chromatography (MEKC). The influence of the buffer pH and the concentration of SDS on the separation of dye mixtures was investigated. The best separation (highly efficient with the large resolution capacity in relatively short time) was accomplished using a buffer at pH 9 enriched with 80 mM SDS. The developed separation method was evaluated, determining the stability of sample (5 h) and buffer (10 h), the limit of detection of dyes (LOD In order to develop a versatile extraction method for compounds from red lipsticks, various types of solvents, temperatures and durations of ultrasound assisted extraction (UAE) were tested. The use of a specially designed and constructed device for repetitive sampling without contamination was suggested. The extraction method was characterized in terms of precision, obtaining very good results for the qualitative (RSD of migration time The proposed UAE/MEKC-DAD method was successfully applied to distinguish red lipstick samples with a very similar hue, achieving a high value of discrimination power (DP = 0.998). It was found that it has great potential in forensic investigations.