Developing Improved Procedures for Lipstick Chromatography

Background: Lipstick chromatography can be used by law enforcement and crime labs to identify if lipstick samples collected as part of an investigation are or are not from the same type of source.3 This method is studied in Liberty University’s Trace Evidence course as the focus of the final lab assignment.3 Problems with the lab surfaced when it was performed during the fall 2024 semester, with most students having no visible transfer of lipstick pigments on their chromatography paper. The purpose of this study was to identify why the students in the lab did not have successful results, and to determine what adjustments can be made to make the lab more successful in the future. Methods: This research primarily studied how the use of different solvents, polar and nonpolar, would affect the results of the lipstick chromatography tests. Additionally, how the quality of the lipstick, the age of the lipstick and amount it has been used, and what type of “lipstick” (any lip-coloring cosmetic) is used would affect the results of the chromatography test were also studied. Three tests were done, two trials each, with all seven solvents used in each test. Results: The most successful solvent was 70 % ethanol, which took an average of 52 minutes and 24 seconds to travel 6 cm and 1 hour 40 minutes and 3 seconds to travel 9 cm, with the pigment transfer being clearly visible. The high quality lipstick had no visible pigment transfer or a very faintly visible pigment transfer with more of the solvents than the medium-quality sample or the low-quality samples. Solid lipstick was the only lip-coloring cosmetic that worked with all of the solvents. The age of the lipstick and amount it had been used did not affect how well chromatography worked for the samples, with an old lipstick and new lipstick producing the exact same results. Conclusions: The results of this research suggested that in order to make the lab the most successful, 70 % ethanol and a solid, medium- or low-quality lipstick should be used. The age of the lipstick and how much it has been used will not affect the results of the chromatography test.