Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2011
This work aimed at characterization of a black layer covering a Bronze Age (period VI) pot surfac... more This work aimed at characterization of a black layer covering a Bronze Age (period VI) pot surface. To solve research problems plane polarized light microscopy (PLM), scanning microscopy with X-ray microanalyser (SEM/EDS), Raman and FTIR microspectroscopies were applied. Observation of the black layer under the PLM suggests that we deal with an opaque, isotropic layer, purposely put on leather-hard, burnished surface of a pot. No traces of organic substances that might have modified a pot surface before painting were detected. The black layer coats the pot with a continuous 0.2-0.4 m thick layer. The black layer must have been applied while warm or hot. It is recognized that the black layer is a true painting layer. Spectroscopic analyses (Raman and FTIR) point that birch tar or a birch-pine tar had been applied. Carbon black should be definitely excluded. The analyzed organic substance is structurally ordered in various degrees, due to varying temperature influence. Some Raman spectra reveal, in second-order region of the spectrum (>2000 cm −1 ), the graphite presence. Scarce points reveal the presence of inorganic admixtures: clay minerals, feldspars and quartz. The next question is: Is it an organic paint or a carbon-based, "mixed" paint? Inorganic admixtures are only casual. Relatively high concentration of alumina is expected to have appeared due to aluminum mobility in acidic environment and this was provided by organic tar/pitch substances. Phosphorus (usually with calcium) mostly concentrates together with clay minerals. Thus, hypothesis on bone powder or ash addition to tar/pitch should be excluded. Some elements may originate not only from inorganic substances but also from wood ashes.
The examination and identification of automobile paints is an important problem in road accidents... more The examination and identification of automobile paints is an important problem in road accidents investigations. Since the real sample available is very small, only sensitive microtechniques can be applied. The methods of optical microscopy and micro-Fourier transform infrared spectroscopy (MK-FTIR) supported by scanning electron microscopy together with X-ray microanalysis (SEM-EDX) allow one to carry out the examination of each paint layer without any separation procedure. In this paper an attempt is made to discriminate between different automobile paints of the same colour by the use of these methods for criminalistic investigations. ᭧
Identification of spray paint coats on various surfaces (usually plaster) is often a subject matt... more Identification of spray paint coats on various surfaces (usually plaster) is often a subject matter of forensic examination. The layer of paint, which creates an inscription, smudge or a drawing, is thin and difficult to be separated from the base. Model examinations have been carried out aiming at the evaluation of the usefulness of the reflection technique of microinfrared spectrometry in the identification of paints. About 20 spray paints, available on the Polish market,-white and black-were placed on the surface in the form of metal, glass, foil, fabric and a wall made of brick, plaster board and mineral plaster. It was found out that, obtaining a reflectance spectrum suitable for identification of the type of paint depends on the thickness of the paint coat and on the type of the base. It was observed that, the smoother and less absorptive the base is the less is its influence deforming the reflection spectrum of paint. q
Infrared microspectrometry and Raman spectroscopy have been applied for examination of multilayer... more Infrared microspectrometry and Raman spectroscopy have been applied for examination of multilayer fragments of paints, for criminalisctic purposes. The study showed that under the conditions used, Raman spectra in the visible range (633 nm) provided data on the pigments but gave little or no information about polymers. Infrared was found to be good for characterising the polymer but failed to provide useful data on some pigments. The results suggest that in many cases the identification of at least the main pigments should be feasible by Raman. The presence of identified pigments was confirmed by means of m-XRF technique. q
The aim of research was to compare two adsorbents, Tenax TA s and Carbotrap 300 s , to evaluate t... more The aim of research was to compare two adsorbents, Tenax TA s and Carbotrap 300 s , to evaluate their usefulness as passive adsorbents of flammable liquids compounds. It was also to determine whether Carbotrap 300 s could be used in a passive adsorption mode, contrary to manufacturer recommendations. To compare the adsorption properties and the thermal desorption efficiency for Tenax TA s and Carbotrap, the components of test mixture were adsorbed and then chromatographically analyzed. The analysis was conducted by means of an automated thermal desorber coupled with a gas chromatograph and a mass spectrometer. This research established that although these adsorbents significantly differ from each other in adsorption properties, each of them can be successfully used for passive adsorption of ignitable liquids compounds. Tenax TA s turned out to be more effective for the adsorption of nonpolar, high-boiling compounds, whereas Carbotrap is more effective for polar and volatile compounds. The examined adsorbents differ in their susceptibility to thermal desorption. For Carbotrap 300 s , after the analysis an additional treatment is required to remove the remnants of adsorbed compounds. With Tenax TA s , this additional step is not necessary because the thermal desorption is sufficiently effective that this product is immediately ready for re-use.
Tiny glass fragments of two typical objects being of interest in forensic investigations: car win... more Tiny glass fragments of two typical objects being of interest in forensic investigations: car windscreen and windowpane were examined from the point of view of their importance as crime evidence. Both examined objects were made from float glass and were toughened. The present paper concerns examination of refractive index distribution across the objects under investigation before and after the glass fragments were annealed according to previously chosen procedure. The annealing procedure was carried out in order to increase discrimination power of refractive index (RI). The following conclusions can be drawn from the results obtained. For both examined objects the mean RI was significantly higher after annealing and, at the same time, standard deviations in RI were smaller. The distributions of RI for both examined objects appeared not to be normal; the deviations from normality were observed at both sides of RI distributions. It was found that the difference in the values DRI (difference between mean values of RI after annealing and before annealing) for both examined object was not significant and thus it would be not a good parameter to differentiate between two heat strengthen objects. The attempt to classify 181 glass samples on the basis of theirs RI and DRI was performed. Increased discrimination of glass samples was observed. #
This study was undertaken to apply a new method of controlling type I error when performing pairw... more This study was undertaken to apply a new method of controlling type I error when performing pairwise comparisons. The Benjamini and Hochberg false discovery rate (FDR) controlling procedures have proved to be very powerful tools in solving many practical problems but have not yet been applied to pairwise comparisons of refractive index of glass samples. Students t-test and Welch test (unequal variance Student's t-test) were applied to all possible pairwise comparisons. The comparisons were made on the basis of refractive index values of 72 glass fragments from different car windows and 69 different fragments from one windscreen. The type I error was controlled by the use of Benjamini and Hochberg false discovery rate (FDR) controlling procedure. To illustrate the importance of controlling type I error when using pairwise comparisons, results of pairwise comparisons with the FDR controlling procedure were compared to those comparisons made without any controlling procedure. Significantly fewer false negative results (false rejection of H0) were found during the use of FDR procedure in the comparison of refractive indices from the same windscreen than when comparing without controlling type I error. The results of application of FDR method were also compared to the results of other post-hoc tests, such as Tukey HSD test and Bonfferoni test. The FDR method has higher power than Bonferroni method and Tukey HSD method and control errors better than comparing without controlling type I error. The method of choice, for pairwise comparison of glass fragments on the basis of refractive index is Welch test with FDR adjustment. The method gave type I errors at level about 5.3% and type II error at about 3.7%.
Two kinds of motor oil were examined with respect to changes in their elemental composition durin... more Two kinds of motor oil were examined with respect to changes in their elemental composition during car driving. The concentrations of Ba, Ca, Mg, Zn, Cu, Fe, Pb and Cd in oil samples were determined by flame atomic absorption spectrometry. Significant differences in the metal concentrations of oil samples used during normal car service were observed. Quantitative elemental composition of oils can be recommended as a good feature for differentiation between various oil samples for criminalistic purposes.
Sixteen kinds of mineral, synthetic and semisynthetic motor oils were examined by the FTIR, XRF a... more Sixteen kinds of mineral, synthetic and semisynthetic motor oils were examined by the FTIR, XRF and AAS methods. It was found that infrared spectroscopy supported by the quantitative elemental analysis provides information on the additives and can be recommended in most cases for differentiation between various oil samples for criminalistic purposes. ᭧
Two brands of motor oils, Elf and Castrol, were examined for criminalistic purposes. The aim was ... more Two brands of motor oils, Elf and Castrol, were examined for criminalistic purposes. The aim was to distinguish between oil samples of varying degree of use. The chemical composition of the oils expressed by their infrared spectra was the basis of investigations. The mathematical approach applied to processing and interpretation of the physicochemical data was a chemometric procedure consisting of a few stages and including such methods as factor and cluster analysis. It was shown that the procedure presented can be recommended as very helpful for qualitative estimation of the effects examined. q
A method of subtraction and normalization of IR spectra (MSN-IR) was developed and successfully a... more A method of subtraction and normalization of IR spectra (MSN-IR) was developed and successfully applied to extract mathematically the pure paint spectrum from the spectrum of paint coat on different bases, both acquired by the Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) technique. The method consists of several stages encompassing several normalization and subtraction processes. The similarity of the spectrum obtained with the reference spectrum was estimated by means of the normalized Manhattan distance. The utility and performance of the method proposed were tested by examination of five different paints sprayed on plastic (polyester) foil and on fabric materials (cotton). It was found that the numerical algorithm applied is able -in contrast to other mathematical approaches conventionally used for the same aim -to reconstruct a pure paint IR spectrum effectively without a loss of chemical information provided. The approach allows the physical separation of a paint from a base to be avoided, hence a time and work-load of analysis to be considerably reduced. The results obtained prove that the method can be considered as a useful tool which can be applied to forensic purposes.
Two brands of motor oils (Elf and Castrol) that had been used for various periods of time were ex... more Two brands of motor oils (Elf and Castrol) that had been used for various periods of time were examined. The aim was to differentiate these samples (of varying degree of use) on the basis of their infrared spectra, for criminalistic purposes. The correlation method was used. It was found that the FTIR method is capable of providing sufficiently detailed information if some specific fragments of spectra are examined. Hence, it can be concluded that the investigation procedure proposed is adequate.
The ap pli ca tion of py rol y sis-gas chro ma tog ra phy (Py-GC) to car paint anal y sis for fo ... more The ap pli ca tion of py rol y sis-gas chro ma tog ra phy (Py-GC) to car paint anal y sis for fo ren sic pur poses has been re viewed in this pa per. The prin ci ples of the method and their ap pli ca tion to paint anal y sis are de scribed. On the ba sis of the lit er a ture, the structure of the ap plied ap pa ra tuses is also pre sented. More over, var i ous tech niques and pro ce dures that can be car ried out us ing Py-GC anal y sis are de scribed as well. Re sults ob tained by ap pli ca tion of this method in var i ous fo ren sic lab o ra to ries over the last few de cades at test to the fact that the equip ment and meth od ol ogy are con stantly be ing de vel oped -it is be com ing an an a lyt i cal tool with very great iden ti fi ca tion and dis crim i na tion po ten tial.
Third International Symposium on Information Assurance and Security, 2007
Daniel Ramos and Joaquin Gonzalez-Rodriguez, ATVS - Biometric Recognition Group, Universidad Auto... more Daniel Ramos and Joaquin Gonzalez-Rodriguez, ATVS - Biometric Recognition Group, Universidad Autonoma de Madrid, Spain; daniel.ramos@uam.es ... Institute of Forensic Research, Westerplatte 9, 31-033 Krakow, Poland; gzadora@ies.krakow.pl ... Colin Aitken, School of ...
The aim of the presented study was to elaborate a procedure for detect- ing and identifying organ... more The aim of the presented study was to elaborate a procedure for detect- ing and identifying organic accelerants in samples taken from the site of a fire. In the analysis of fire debris, a key-stage is the preparation of samples, encompassing sepa- rating of analytes from the matrix and concentrating them. In the elaborated proce- dure, head-space analysis with passive
Micro-Raman spectroscopy was applied to forensic identification of pigments in paint chips and pr... more Micro-Raman spectroscopy was applied to forensic identification of pigments in paint chips and provided differentiation between paint samples. Sixty-six blue automotive paint samples, 26 solid and 40 metallic were examined. It was found that the majority of the collected Raman spectra provided information about the pigments present. However, in some cases, fluorescence precluded pigment identification. Using laser excitation at longer wavelengths or pretreatment to effect photobleaching often resulted in reduced fluorescence, particularly for solid color samples, and allowed pigment identification. The examined samples were compared pairwise taking into account number, location, and intensity of absorption bands in their infrared spectra. The estimated discrimination power ranged from 97% for solid paint samples to 99% for metallic paint samples.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2011
This work aimed at characterization of a black layer covering a Bronze Age (period VI) pot surfac... more This work aimed at characterization of a black layer covering a Bronze Age (period VI) pot surface. To solve research problems plane polarized light microscopy (PLM), scanning microscopy with X-ray microanalyser (SEM/EDS), Raman and FTIR microspectroscopies were applied. Observation of the black layer under the PLM suggests that we deal with an opaque, isotropic layer, purposely put on leather-hard, burnished surface of a pot. No traces of organic substances that might have modified a pot surface before painting were detected. The black layer coats the pot with a continuous 0.2-0.4 m thick layer. The black layer must have been applied while warm or hot. It is recognized that the black layer is a true painting layer. Spectroscopic analyses (Raman and FTIR) point that birch tar or a birch-pine tar had been applied. Carbon black should be definitely excluded. The analyzed organic substance is structurally ordered in various degrees, due to varying temperature influence. Some Raman spectra reveal, in second-order region of the spectrum (>2000 cm −1 ), the graphite presence. Scarce points reveal the presence of inorganic admixtures: clay minerals, feldspars and quartz. The next question is: Is it an organic paint or a carbon-based, "mixed" paint? Inorganic admixtures are only casual. Relatively high concentration of alumina is expected to have appeared due to aluminum mobility in acidic environment and this was provided by organic tar/pitch substances. Phosphorus (usually with calcium) mostly concentrates together with clay minerals. Thus, hypothesis on bone powder or ash addition to tar/pitch should be excluded. Some elements may originate not only from inorganic substances but also from wood ashes.
The examination and identification of automobile paints is an important problem in road accidents... more The examination and identification of automobile paints is an important problem in road accidents investigations. Since the real sample available is very small, only sensitive microtechniques can be applied. The methods of optical microscopy and micro-Fourier transform infrared spectroscopy (MK-FTIR) supported by scanning electron microscopy together with X-ray microanalysis (SEM-EDX) allow one to carry out the examination of each paint layer without any separation procedure. In this paper an attempt is made to discriminate between different automobile paints of the same colour by the use of these methods for criminalistic investigations. ᭧
Identification of spray paint coats on various surfaces (usually plaster) is often a subject matt... more Identification of spray paint coats on various surfaces (usually plaster) is often a subject matter of forensic examination. The layer of paint, which creates an inscription, smudge or a drawing, is thin and difficult to be separated from the base. Model examinations have been carried out aiming at the evaluation of the usefulness of the reflection technique of microinfrared spectrometry in the identification of paints. About 20 spray paints, available on the Polish market,-white and black-were placed on the surface in the form of metal, glass, foil, fabric and a wall made of brick, plaster board and mineral plaster. It was found out that, obtaining a reflectance spectrum suitable for identification of the type of paint depends on the thickness of the paint coat and on the type of the base. It was observed that, the smoother and less absorptive the base is the less is its influence deforming the reflection spectrum of paint. q
Infrared microspectrometry and Raman spectroscopy have been applied for examination of multilayer... more Infrared microspectrometry and Raman spectroscopy have been applied for examination of multilayer fragments of paints, for criminalisctic purposes. The study showed that under the conditions used, Raman spectra in the visible range (633 nm) provided data on the pigments but gave little or no information about polymers. Infrared was found to be good for characterising the polymer but failed to provide useful data on some pigments. The results suggest that in many cases the identification of at least the main pigments should be feasible by Raman. The presence of identified pigments was confirmed by means of m-XRF technique. q
The aim of research was to compare two adsorbents, Tenax TA s and Carbotrap 300 s , to evaluate t... more The aim of research was to compare two adsorbents, Tenax TA s and Carbotrap 300 s , to evaluate their usefulness as passive adsorbents of flammable liquids compounds. It was also to determine whether Carbotrap 300 s could be used in a passive adsorption mode, contrary to manufacturer recommendations. To compare the adsorption properties and the thermal desorption efficiency for Tenax TA s and Carbotrap, the components of test mixture were adsorbed and then chromatographically analyzed. The analysis was conducted by means of an automated thermal desorber coupled with a gas chromatograph and a mass spectrometer. This research established that although these adsorbents significantly differ from each other in adsorption properties, each of them can be successfully used for passive adsorption of ignitable liquids compounds. Tenax TA s turned out to be more effective for the adsorption of nonpolar, high-boiling compounds, whereas Carbotrap is more effective for polar and volatile compounds. The examined adsorbents differ in their susceptibility to thermal desorption. For Carbotrap 300 s , after the analysis an additional treatment is required to remove the remnants of adsorbed compounds. With Tenax TA s , this additional step is not necessary because the thermal desorption is sufficiently effective that this product is immediately ready for re-use.
Tiny glass fragments of two typical objects being of interest in forensic investigations: car win... more Tiny glass fragments of two typical objects being of interest in forensic investigations: car windscreen and windowpane were examined from the point of view of their importance as crime evidence. Both examined objects were made from float glass and were toughened. The present paper concerns examination of refractive index distribution across the objects under investigation before and after the glass fragments were annealed according to previously chosen procedure. The annealing procedure was carried out in order to increase discrimination power of refractive index (RI). The following conclusions can be drawn from the results obtained. For both examined objects the mean RI was significantly higher after annealing and, at the same time, standard deviations in RI were smaller. The distributions of RI for both examined objects appeared not to be normal; the deviations from normality were observed at both sides of RI distributions. It was found that the difference in the values DRI (difference between mean values of RI after annealing and before annealing) for both examined object was not significant and thus it would be not a good parameter to differentiate between two heat strengthen objects. The attempt to classify 181 glass samples on the basis of theirs RI and DRI was performed. Increased discrimination of glass samples was observed. #
This study was undertaken to apply a new method of controlling type I error when performing pairw... more This study was undertaken to apply a new method of controlling type I error when performing pairwise comparisons. The Benjamini and Hochberg false discovery rate (FDR) controlling procedures have proved to be very powerful tools in solving many practical problems but have not yet been applied to pairwise comparisons of refractive index of glass samples. Students t-test and Welch test (unequal variance Student's t-test) were applied to all possible pairwise comparisons. The comparisons were made on the basis of refractive index values of 72 glass fragments from different car windows and 69 different fragments from one windscreen. The type I error was controlled by the use of Benjamini and Hochberg false discovery rate (FDR) controlling procedure. To illustrate the importance of controlling type I error when using pairwise comparisons, results of pairwise comparisons with the FDR controlling procedure were compared to those comparisons made without any controlling procedure. Significantly fewer false negative results (false rejection of H0) were found during the use of FDR procedure in the comparison of refractive indices from the same windscreen than when comparing without controlling type I error. The results of application of FDR method were also compared to the results of other post-hoc tests, such as Tukey HSD test and Bonfferoni test. The FDR method has higher power than Bonferroni method and Tukey HSD method and control errors better than comparing without controlling type I error. The method of choice, for pairwise comparison of glass fragments on the basis of refractive index is Welch test with FDR adjustment. The method gave type I errors at level about 5.3% and type II error at about 3.7%.
Two kinds of motor oil were examined with respect to changes in their elemental composition durin... more Two kinds of motor oil were examined with respect to changes in their elemental composition during car driving. The concentrations of Ba, Ca, Mg, Zn, Cu, Fe, Pb and Cd in oil samples were determined by flame atomic absorption spectrometry. Significant differences in the metal concentrations of oil samples used during normal car service were observed. Quantitative elemental composition of oils can be recommended as a good feature for differentiation between various oil samples for criminalistic purposes.
Sixteen kinds of mineral, synthetic and semisynthetic motor oils were examined by the FTIR, XRF a... more Sixteen kinds of mineral, synthetic and semisynthetic motor oils were examined by the FTIR, XRF and AAS methods. It was found that infrared spectroscopy supported by the quantitative elemental analysis provides information on the additives and can be recommended in most cases for differentiation between various oil samples for criminalistic purposes. ᭧
Two brands of motor oils, Elf and Castrol, were examined for criminalistic purposes. The aim was ... more Two brands of motor oils, Elf and Castrol, were examined for criminalistic purposes. The aim was to distinguish between oil samples of varying degree of use. The chemical composition of the oils expressed by their infrared spectra was the basis of investigations. The mathematical approach applied to processing and interpretation of the physicochemical data was a chemometric procedure consisting of a few stages and including such methods as factor and cluster analysis. It was shown that the procedure presented can be recommended as very helpful for qualitative estimation of the effects examined. q
A method of subtraction and normalization of IR spectra (MSN-IR) was developed and successfully a... more A method of subtraction and normalization of IR spectra (MSN-IR) was developed and successfully applied to extract mathematically the pure paint spectrum from the spectrum of paint coat on different bases, both acquired by the Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) technique. The method consists of several stages encompassing several normalization and subtraction processes. The similarity of the spectrum obtained with the reference spectrum was estimated by means of the normalized Manhattan distance. The utility and performance of the method proposed were tested by examination of five different paints sprayed on plastic (polyester) foil and on fabric materials (cotton). It was found that the numerical algorithm applied is able -in contrast to other mathematical approaches conventionally used for the same aim -to reconstruct a pure paint IR spectrum effectively without a loss of chemical information provided. The approach allows the physical separation of a paint from a base to be avoided, hence a time and work-load of analysis to be considerably reduced. The results obtained prove that the method can be considered as a useful tool which can be applied to forensic purposes.
Two brands of motor oils (Elf and Castrol) that had been used for various periods of time were ex... more Two brands of motor oils (Elf and Castrol) that had been used for various periods of time were examined. The aim was to differentiate these samples (of varying degree of use) on the basis of their infrared spectra, for criminalistic purposes. The correlation method was used. It was found that the FTIR method is capable of providing sufficiently detailed information if some specific fragments of spectra are examined. Hence, it can be concluded that the investigation procedure proposed is adequate.
The ap pli ca tion of py rol y sis-gas chro ma tog ra phy (Py-GC) to car paint anal y sis for fo ... more The ap pli ca tion of py rol y sis-gas chro ma tog ra phy (Py-GC) to car paint anal y sis for fo ren sic pur poses has been re viewed in this pa per. The prin ci ples of the method and their ap pli ca tion to paint anal y sis are de scribed. On the ba sis of the lit er a ture, the structure of the ap plied ap pa ra tuses is also pre sented. More over, var i ous tech niques and pro ce dures that can be car ried out us ing Py-GC anal y sis are de scribed as well. Re sults ob tained by ap pli ca tion of this method in var i ous fo ren sic lab o ra to ries over the last few de cades at test to the fact that the equip ment and meth od ol ogy are con stantly be ing de vel oped -it is be com ing an an a lyt i cal tool with very great iden ti fi ca tion and dis crim i na tion po ten tial.
Third International Symposium on Information Assurance and Security, 2007
Daniel Ramos and Joaquin Gonzalez-Rodriguez, ATVS - Biometric Recognition Group, Universidad Auto... more Daniel Ramos and Joaquin Gonzalez-Rodriguez, ATVS - Biometric Recognition Group, Universidad Autonoma de Madrid, Spain; daniel.ramos@uam.es ... Institute of Forensic Research, Westerplatte 9, 31-033 Krakow, Poland; gzadora@ies.krakow.pl ... Colin Aitken, School of ...
The aim of the presented study was to elaborate a procedure for detect- ing and identifying organ... more The aim of the presented study was to elaborate a procedure for detect- ing and identifying organic accelerants in samples taken from the site of a fire. In the analysis of fire debris, a key-stage is the preparation of samples, encompassing sepa- rating of analytes from the matrix and concentrating them. In the elaborated proce- dure, head-space analysis with passive
Micro-Raman spectroscopy was applied to forensic identification of pigments in paint chips and pr... more Micro-Raman spectroscopy was applied to forensic identification of pigments in paint chips and provided differentiation between paint samples. Sixty-six blue automotive paint samples, 26 solid and 40 metallic were examined. It was found that the majority of the collected Raman spectra provided information about the pigments present. However, in some cases, fluorescence precluded pigment identification. Using laser excitation at longer wavelengths or pretreatment to effect photobleaching often resulted in reduced fluorescence, particularly for solid color samples, and allowed pigment identification. The examined samples were compared pairwise taking into account number, location, and intensity of absorption bands in their infrared spectra. The estimated discrimination power ranged from 97% for solid paint samples to 99% for metallic paint samples.
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