Stable Isotope Analysis of Human Hair and Nail Samples: The Effects of Storage on Samples.

When submitting samples for analysis, maintaining sample integrity is essential. Appropriate packaging must be used to prevent damage, contamination or loss of sample. This is particularly important for stable isotope analysis by isotope ratio mass spectrometry as this technique is capable of detecting subtle differences in isotopic composition with great precision. In a novel study, scalp hair and fingernail samples were placed in five different types of packaging, routinely used in forensic laboratories and stored for 6 weeks and 6 months. Samples were subsequently cleaned and submitted for ¹³C/¹²C, ¹⁵N/¹⁴N, ²H/¹H and ¹⁸O/¹⁶O analysis. Results from ¹³C analysis indicate that type of packaging can cause slight changes in ¹³C abundance over time. Differences were noted in the ¹⁵N isotope signatures of both hair and nail samples after 6-week storage, but not after 6 months. This apparent discrepancy could be a result of the packaging not being properly sealed in the 6 weeks study. Fewer differences were noted when analyzing samples for ²H and ¹⁸O abundance. [ABSTRACT FROM AUTHOR]