Forensic science analysis of soil samples for the presence of flammable liquids occasionally results in the detection of volatile mixtures that lack some of the diagnostic features of common petroleum products. The presence of these mixtures is not consistent with evaporation or with a chemical or physical process, but is reported in microbiological literature that addresses bacterial degradation. Microbiological research has shown that crude oil spilled in the environment is sometimes degraded by bacteria. A study was conducted to demonstrate how automotive gasoline is degraded. Gasoline was spiked into 36 containers of soil (12 were stored at −5°C; 12 were stored at room temperature; and 12 of the soil samples were sterilized prior to the addition of the gasoline and were then stored at room temperature). These samples were monitored, and the results were compared using static heated headspace sampling and capillary gas chromatography. The gasoline in the unsterilized samples stored at room temperature degraded rapidly, while the gasoline in the other two sets of samples was unaffected. This degradation followed trends that can be recognized in casework and can assist in the identification of affected petroleum product residues in soil.

Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) is a recently developed technique that offers several significant advantages over conventional methods of sampling solids. Some of these include: (1) minimal sample preparation (no sample preparation in a few cases); (2) a very wide range of sample concentrations which yield useful spectra; and (3) a very high sensitivity (less than 100 ng in some cases). DRIFTS has been applied to the analysis of a number of materials of forensic science interest. Specific applications for a variety of evidence types have been found; this work is therefore presented as a series. This paper presents the principles of the technique and examples of the sampling methods, including a microsampling method for liquids. Some of the unique advantages that DRIFTS offers for forensic science work, including better characterization of many compounds, are illustrated. In addition, an explanation of these DRIFTS features is discussed.

Many types of polymeric organic foams, which comprise items such as thermal insulation, packaging materials, furniture and garment fillings, carpet padding, and so forth, can be sampled directly using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Some of the advantages of direct DRIFTS sampling include: (1) no sample preparation is required, (2) the method is completely nondestructive, and (3) the method provides more spectral information for characterizing and individualizing particular substances than many alternative techniques do. Several examples illustrating the direct DRIFTS analysis of a variety of foam articles are presented and discussed.

Clorazepate presents several problems in identification. In addition to rapid acid decarboxylation to N-desmethyldiazepam, a noncontrolled substance often confused with clorazepate, extracts of the pharmaceutical forms (Tranxene™ and Azenez™ capsules) contain substances that interfere with isolation of intact and unaltered clorazepate. These substances have been identified and have been found to be quite dependent on both capsule type and, especially, on capsule age. The cause of the conversion of dipotassium clorazepate to the monopotassium salt, following solution, has also been identified. An infrared analysis method, which removes all of the interferences, is presented.

Fuller and Griffiths first demonstrated the feasibility of obtaining an infrared spectrum directly on an intact Empirin® tablet using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). We have found that several modifications of this method are necessary to obtain useful spectra for most other tablets. Applications of these modified procedures to the analysis of several tablets of forensic science interest are presented, and the results are compared to those obtained by conventional means. The direct analysis of some capsule contents and other powders is also presented and discussed.