For the most part, forensic chemistry is very similar to analytical chemistry. Among the typical job functions of an analytical chemist are: performing qualitative and quantitative analysis; sampling, setting error limits, validating and verifying results through calibration and standardization; and interpreting data in proper context.²  Forensic chemistry does all these, certainly, but it differs from other types of chemistry in several ways, one of which is central to the topic of this chapter: where its samples come from and what that means for interpretation of those samples, that is, could they have come from the same source. Both qualitative...