Extraction of diatoms from (cotton) clothing for forensic comparisons

Diatoms in clothing can be used to determine contact with surface water and contact with a specific water source, which can help link suspects to crime scenes. However, for the study of diatoms it is imperative that they are first extracted from the clothing under investigation. In this study we tested three methods for extracting diatoms from cotton clothing: rinsing with water (RW), rinsing with ethanol (RE) and the dissolution of cotton with nitric and sulphuric acid (DI). The DI method produced the highest average yield and can be used to determine contact with water. The RE method extracted reproducible numbers of diatoms from two different T-shirts and the resulting species compositions were similar to their relevant reference water samples. Therefore, we present rinsing with ethanol as an effective extraction method for the qualitative and quantitative analysis of diatoms in (cotton) clothing.