title: Differentiation of Body Fluid Stains on Fabrics Using External Reflection Fourier Transform Infrared Spectroscopy (FT-IR) and Chemometrics.
abstract: Body fluids are evidence of great forensic interest due to the DNA extracted from them, which allows genetic identification of people. This study focuses on the discrimination among semen, vaginal fluid, and urine stains (main fluids in sexual crimes) placed on different colored cotton fabrics by external reflection Fourier transform infrared spectroscopy (FT-IR) combined with chemometrics. Semen-vaginal fluid mixtures and potential false positive substances commonly found in daily life such as soaps, milk, juices, and lotions were also studied. Results demonstrated that the IR spectral signature obtained for each body fluid allowed its identification and the correct classification of unknown stains by means of principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA). Interestingly, results proved that these IR spectra did not show any bands due to the color of the fabric and no substance of those present in daily life which were analyzed, provided a false positive.
authors.affiliation: Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering and University Institute of Research in Police Sciences (IUICP), University of Alcalá, Alcalá de Henares (Madrid), Spain.
authors.forename: Félix
authors.initials: F
authors.lastname: Zapata
authors.affiliation: Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering and University Institute of Research in Police Sciences (IUICP), University of Alcalá, Alcalá de Henares (Madrid), Spain.
authors.forename: Ma Ángeles Fernández
authors.initials: MÁ
authors.lastname: de la Ossa
authors.affiliation: Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering and University Institute of Research in Police Sciences (IUICP), University of Alcalá, Alcalá de Henares (Madrid), Spain carmen.gruiz@uah.es.
authors.forename: Carmen
authors.initials: C
authors.lastname: García-Ruiz
mesh_terms: D001826:Body Fluids / Q000737:chemistry*; D032561:Cotton Fiber; D005260:Female; D005554:Forensic Medicine / Q000379:methods; D006801:Humans; D008297:Male; D025341:Principal Component Analysis; D012661:Semen / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D013784:Textiles / Q000032:analysis; D016482:Urinalysis / Q000379:methods; D014621:Vagina / Q000737:chemistry
keywords: External reflection Fourier transform infrared spectroscopy (FT-IR); Principal component analysis (PCA); Semen; Soft independent modeling of class analogy (SIMCA); Urine; Vaginal fluid