Sample preparation for chromatographic applications in forensic science

This chapter covers the many basic steps that may be involved in the preparation of gas, liquid, solid, or mixed samples in forensic applications. Although the ultimate aim of good sample preparation is to use the minimum number of preparation steps, the reasons for each step are outlined. The preparation of samples for forensic investigations includes many varied samples in many matrices. The different steps that can be combined - physical separation, separation of phases, filtration, precipitation, centrifugation, vortexing/mixing, selective adsorption/release, derivatization, pre-concentration, dilution, and separation by partition between two liquids - are considered. In addition to the classic sample preparation for gas and liquid chromatography, sample preparation for ion chromatography, liquid chromatography coupled to inductively coupled plasma mass spectrometry, and stable isotope ratio mass spectrometry are considered because they are being used more in chromatographic investigations in forensic science. The chapter concludes with advice to scientists involved in designing new sample preparation methods and outlines useful avenues to determine if a suitable method already exists or an existing method could be modified to meet the criteria so that we do not reinvent the wheel.