Rapid Presumptive “Fingerprinting” of Body Fluids and Materials by ATR FT‐IR Spectroscopy*^,†

Abstract

Human body fluids and materials were evaluated using attenuated total reflectance Fourier transform infrared spectroscopy. Purified proteins, cosmetics, and foodstuffs were also assayed with the method. The results of this study show that the sampled fluids and materials vary in the fingerprint region and locations of the amide I peaks because of the secondary structure of the composite proteins although the C = O stretch is always present. The distinct 1016 cm(-1) peak serves as a signature for semen. The lipid-containing materials (e.g., fingerprints, earwax, tears, and skin) can also be easily separated from the aqueous materials because of the strong CH(3) asymmetric stretch of the former. Blood-saliva and blood-urine mixtures were also successfully differentiated using combinations of peaks. Crime scene investigators employing rapid, portable, or handheld infrared spectroscopic instruments may be able to reduce their need for invasive, destructive, and consumptive presumptive test reagents in evaluating trace evidence.

Does dentifrice provide the necessary saturation of ions in oral fluids to favour remineralisation?

“…how the use of the IR spectroscopy method allows the study of samples of mixed saliva. As noted in [36], the use of any medications is revealed in the molecular spectra of mixed saliva as also confirmed in [39,40]. Hence, the application of IRspectroscopy for the analysis of the changes in the molecular composition of the oral fluid is a logical and tested approach demonstrating high-precision results [4,5,41,36].…”

Body Fluids and Spectroscopic Techniques in Forensics: A Perfect Match?

“…The reviewed studies confirm that IR and Raman spectroscopy are highly suitable for the discrimination among body fluids. In addition no false positive substances have been found which may be erroneously identified as body fluids by these techniques [18,19,21,24,26]. Both IR and Raman spectroscopy are very selective, rapid, non-destructive and all the other features previously assessed for spectroscopic techniques.…”

“…Regarding IR spectroscopy, the MIR range is the most appropriate for identification purposes because it is more informative and therefore provides higher selectivity and confidence to confirm a body fluid [1]. Both ATR and external reflectance modes, working in MIR range, have demonstrated their capabilities to identify and differentiate body fluids, while it is true that external reflectance is preferable to ATR for the analysis of stains, as stated above [24][25][26]. Nevertheless, both external reflectance and ATR are being preliminary investigated at the moment for the discrimination of stains of body fluids and it will take time until overwhelming results prove the superiority of these techniques.…”

“…For example, a large part of the studies were carried out by analysing samples of body fluids on glass slides or directly placed onto the instrument [25,[33][34][35][36][37][38][39][40][41], which is an extremely unusual substrate in real cases. In addition, studies in which stains were prepared on different clothes such as cotton, polyester, acrylic or wool, exclusively correspond to blood [18][19][20][21][22][23]27,30,31] except for studies [24,26]. There are still some unsolved questions concerning the identification of stains of body fluids (particularly semen, vaginal fluid, saliva, urine and sweat) on fabrics, such as the influence of the fabric material and colour to the IR or Raman spectrum.…”

“…For instance, Elkins [24] studied the identification of blood, semen, saliva, vaginal fluid and urine stains on white cotton by ATR in the MIR region based on the characteristic spectral bands of each body fluid. In addition, other substances such as coffee, wine, chocolate, cheese, yogurt and lotions, amongst others, were tested as false positives.…”