Forensic chemical study on human hair. IV. Identification of brand of hair sprays and hair growth promoters by components remaining on human hair, and example of forensic hair examination.

Abstract

Investigation was made on means of identifying components of hair sprays and hair growth promoters remaining on human hair. Twelve brands of hair spray of 8 manufacturers and 11 brands of hair growth promoter of 7 manufacturers were identified by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Components of 4 brands of hair sprays and 2 brands of hair growth promoters remaining on hair were discriminated by GC and GC-MS. The 6 brands were classified into 4 groups on the basis of these components, and 3 of them were distinguishable by characteristic peak(s) detected by the two methods used. The component of one brand of hair growth promoter was detected even 20 d after application. One other component, that had not been detected in earlier studies on men's and women's hair care products and oxidative dyes was identified in 3 of 4 brands of hair spray. Two components (cetyl alcohol and stearyl alcohol) of one brand of hair growth promoter which remained on human hair were the same as those of women's hair care products and oxidative dyes, but this may not be interfere with brand identification since the hair growth promoter was only for men. In the application of this method to an actual crime, components of hair care products remaining on hairs adhering to a suspect's clothing were analyzed by GC and GC-MS, since morphological investigation had shown that some of these hairs were partially different from the victim's head hairs. The five main components remaining on hairs of both the victim and the suspect's clothing were found to be exactly the same. Analysis of components remaining on hairs was thus considered to be more objective method than morphological examination in forensic hair comparison.