Soil can be a useful evidence to link suspect/victim to a particular crime scene or give indication of possible location of the crime scene. In practice, physical properties of soils are less discriminative because soils from different origins could show similar soil colours. Hence, analytical approach for discriminating soils of similar colours but originating from different locations could contribute to the forensic investigation. This study proposes an analytical approach to discriminate five brown soils using ultra-performance liquid chromatography and principal component analysis. The brown soils have been collected from five proximity areas in Bangi, Selangor, Malaysia. The non-volatile organic compounds in the soils were extracted using acetonitrile and analysed via UPLC technique. By injecting each of the samples in triplicate, a total of 15 chromatograms were obtained at 230nm. Each chromatogram was represented by 18 000 retention time points. Due to the high dimensionality, principal component analysis (PCA) has been employed to illustrate the separation of the five soils in a two dimensional scores plot. Results showed that the 15 samples were clustered by their origins and well discriminated from each other in the scores plot of PC1 vs. PC3. Loading plot of PC3 indicated that the peaks eluted in the first five min played vital role in discriminating the five soils. In conclusion, UPLC technique can be a feasible analytical approach for forensic soil analysis.

Discrimination of brown soils using ultra-performance liquid chromatography (UPLC) and principal component analysis

ACS Spring Meeting 2021

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