Kiwook Kim

Distribution of organochlorines and PCB congeners in Korean human tissues

In order to investigate the residual amounts of organochlorines and polychlorinated biphenyls (PCBs) in Korean human tissues (blood, adipose tissue, liver, kidney cortex, and lung), the samples were collected from the autopsied cadavers of 40 men and 40 women (from teens to seventies of age) α-BHC, β-BHC, γ-BHC, σ-BHC,p,p′-DDT,p,p′-DDD,p,p′-DDE, endrin, dieldein, aldrin, and 7 marker PCBs (28, 52, 101, 118, 138, 153, and 180) were determined in human tissues. The levels of organochlorines and PCB congeners indicated that they have been widely distributed in Korean human body. Positive correlations in terms of age were observed for the following cases:p,p′-DDE,p,p′-DDT, θ-DDT, PCB 118, PCB 138, PCB 153, and θ-PCB in the adipose tissue, andp,p′-DDE in the lung. Concentration of these compounds showed a significant age-related increase. Accumulation of these compounds in aged people revealed that these compounds were more slowly eliminated in our environment and risk assessment was necessary for further proper action. Significant differences in the levels of PCBs between genders were found for PCB 118 in the adipose tissue and PCB 138 in the liver. Positive correlation coefficients between tissues were detected withp,p′-DDE and β-BHC.

Forensic Comparison of Soil Samples

As a preliminary experiment to test the discriminating ability of forensic soil analysis techniques and obtain area-specific information, soil samples were collected from eight areas near the eastern branch of the National Forensic Service (NFS) located in Gangwondo, an eastern province of South Korea. The soil samples were collected from five spots within each sample area using a small-scale (1 m2) soil sampling technique; for each of these five spots, two samples were collected from two places in each spot, (i) one from the surface and (ii) another from 30 cm below the surface. For each sample, the color of the sample with particle size in the range 53–500 μm and the major constituents were determined using a spectrophotometer and X-ray fluorescence spectrometer (XRF), respectively. The carbon content and carbon isotope ratio of the part of the sample of particle size below 53 μm were measured using an element analyzer-isotope ratio mass spectrometer (EA-IRMS). The canonical discriminant and XRF analyses showed an excellent color discriminating ability of 87.5 % and 88.8 %, respectively, with respect to the major constituents. The EA-IRMS results showed that the soils obtained from a 30-cm depth below the surface were generally more enriched in δ13C (0/00) than the surface soils, and that the surface soils contained a higher carbon amount (%). The canonical discriminant analysis confirmed 100 % discriminating ability when all three soil characteristics (i.e., color, composition, and content) were used in the analysis. Out of the two functions obtained from the analysis, Function 1 exhibited greater potential for explaining the SiO2, Fe2O3, and TiO2; thus, Area 6 and 7 could be more easily differentiated than the other areas using this function. Function 2 exhibited greater potential for explaining color factor b* (δ13C and C content), and could more efficiently differentiate Area 2 and 5. However, different results were obtained within the same area based on the soil depth. Therefore, when performing a comparative sampling analysis in forensic science, due care should be taken to prevent the mixing of adjacent soils from various depths. Better results can be achieved by collecting soil samples from different spots within the same area.

The analytical application for cement using X-Ray diffraction and X-Ray fluorescence spectrometer

The chemical element and structural characterization of different types of cements and its brick stones are been investigated under forensic aspects using X-ray florescence (XRF) and X-ray diffraction (XRD) spectrometer. The XRF provides rapid compositional data for controlling almost all stages of raw materials, clinker and cement. The decisive advantage of XRD methods is based on the unique character of the diffraction patterns of crystalline substances, the ability to distinguish between elements and their oxides, and the possibility to identify chemical compounds, polymeric forms, and mixed crystals by non-destructive examination. Therefore, combination of these examinations is useful and able to apply for the forensic analysis in comparison of cements and brick stones. There are more study remained to determine the viability of method for forensic analysis of brick stones and the limits of the discrimination that can be achieved.

Comparison of pigment in automotive solid color paints by FT-IR and XRF spectroscopy for forensic aspect

Identification of paint on victim`s clothing and a vehicle are valuable for forensic examination when investigating hit-and-run accidents. Automotive paints on clothes are used to prove a victim caused by traffic accident and to identify a suspected vehicle. The comparison of transferred paints between victim`s vehicle and suspected vehicle can be an important evidence in reconstructing the accident situation and in discovering the truth. The paints such as white, yellow, red, blue, or black are hard to examine particle shape under a stereomicroscope because of it is not included aluminum, pearl, and mica flakes in the pigments. The aim of this study under forensic aspect is to compare pigment among basecoat layers of solid paints by identifying inorganic elemental compositions and binder resins of pigments using by micro-FT-IR and micro-XRF spectrometer. The pigment samples were analyzed by using two methods of FT-IR: Reflectance and ATR method. Two methods of FT-IR were useful in discriminating binder resins of pigments by comparing characteristic peaks and patterns of spectra. Also, XRF spectrometer could identify the elemental compositions in inorganic pigments of trace paints which are difficult to compare the identification by FT-IR.