High Performance Liquid Chromatography as a valuable tool for geoforensic soil analysis

Abstract

A key issue for geoforensic analysis is the ability to discriminate between geographical locations of close proximity, often with similar underlying geology. This paper addresses the lack of empirical research into the non-mineral components of sediment samples and presents the development of a method of sediment sample characterisation by High Performance Liquid Chromatography (HPLC) utilising the organic components of the sample. A sample preparation method and set of instrument parameters were developed such that the cost of the analysis could be reduced, efficiency increased and the sample amount required for analysis reduced fourfold. The re-developed method allows samples collected from different locations within the same forensically relevant site to be accurately discriminated in this study by both visual examination of the chromatography and the use of multivariate statistics. The results of the HPLC analysis were compared with those obtained by quartz grain surface texture analysis, and HPLC was found to offer better discrimination between the samples in this instance. The results of this study suggest that HPLC has the potential to offer an accurate and practical method of comparing soil samples based on characteristics that are independent of, and therefore complementary to, traditional mineralogical-based geoforensic analyses.

Forensic Profiling of Non-Volatile Organic Compounds in Soil using Ultra-Performance Liquid Chromatography: A Pilot Study

“…To the best of our knowledge, previous studies have not reported the retention time repeatability [24,27,28,[30][31][32]. Therefore, an accepted reference value of RSD in forensic soil analysis is unavailable in the literature.…”

“…Three soil samples (red, brown and yellowishbrown soils) were collected from the fern garden of UKM, Malaysia. The soils were sampled following the gridpattern procedure described by Pye [6], which was successfully applied by McCulloch et al [30][31][32]. The procedure enables the researcher to assess the intralocation variability of the soil.…”

“…The soil extraction method was based on the pre vious work of McCulloch et al [30][31][32] with some modification. The samples were first dried in the laboratory at room temperature overnight.…”

“…The mobile phase consisting of (A) water containing 10% ACN and (B) HPLCgrade ACN (Fisher Chemical) was used in three different elution programmes as shown in Table 1. The gradient2 (G2) programme was used by McCulloch et al [30][31][32], whereas the isocratic (ISO) programme was pro posed by Bommarito et al [24]. The gradient1 (G1) programme is an adaptation from the G2 programme and is first reported in this work.…”

“…To address this problem, various sophis ticated instrumental techniques have been explored in the context of forensic soil science, mainly for studying the chemical composition of soil [24][25][26][27][28][29]. Recently, McCulloch et al [30][31][32] published several articles regarding the feasibility of highperformance liquid chromatography (HPLC) in discriminating soils for forensic purposes. The authors concluded that HPLC has the potential to provide an accurate and practical method of differentiating soils origi nating from various proximity areas.…”