Gładysz Marta, Król Małgorzata, Mystek Karolina, Kościelniak Paweł
Laboratory for Forensic Chemistry, Department of Analytical Chemistry, Faculty of Chemistry, Jagiellonian University in Kraków, Gronostajowa 2, 30-387 Kraków, Poland.
Laboratory for Forensic Chemistry, Department of Analytical Chemistry, Faculty of Chemistry, Jagiellonian University in Kraków, Gronostajowa 2, 30-387 Kraków, Poland.
Forensic Sci Int. 2019 Jun;299:49-58. doi: 10.1016/j.forsciint.2019.03.021. Epub 2019 Mar 23.
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 < 1 μg·mL), the repeatability of migration times in one day (RSD < 1.2%), and over three days (RSD < 2.4%), as well as the reproducibility using different capillaries and CE instruments. 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 < 2.0%) and quantitative (RSD of peak height < 10.0%) methods. 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.
本研究的主要目的是应用毛细管电泳（CE）鉴别红色唇膏，这是开发法医鉴定方法的第一步。使用八种染料的混合物和胶束电动毛细管色谱法（MEKC）对分离方法进行了优化。研究了缓冲液pH值和十二烷基硫酸钠（SDS）浓度对染料混合物分离的影响。使用富含80 mM SDS、pH值为9的缓冲液实现了最佳分离（在相对较短的时间内具有高效和高分离能力）。对所开发的分离方法进行了评估，测定了样品（5小时）和缓冲液（10小时）的稳定性、染料的检测限（LOD＜1 μg·mL）、一天内迁移时间的重复性（RSD＜1.2%）和三天内迁移时间的重复性（RSD＜2.4%），以及使用不同毛细管和CE仪器的重现性。为了开发一种从红色唇膏中提取化合物的通用方法，测试了各种类型的溶剂、温度和超声辅助萃取（UAE）的持续时间。建议使用专门设计和构建的无污染重复采样装置。对萃取方法的精密度进行了表征，定性方法（迁移时间的RSD＜2.0%）和定量方法（峰高的RSD＜10.0%）均获得了很好的结果。所提出的UAE/MEKC-DAD方法成功应用于区分色调非常相似的红色唇膏样品，获得了很高的鉴别力值（DP = 0.998）。结果发现，该方法在法医调查中具有巨大潜力。
