Practical GC/MS analysis of oxidation dye components in hair fiber as a forensic investigative procedure

The purpose of this study was to improve the reliability of discrimination (or identification) of dyed hair by analyzing chemical substances present i n the hair, as an addition to the conventional macroscopical and microscopi cal examinations and ABO blood group examination. Oxidation hair-dye compon ents such as p-phenylenediamine (PPDA), toluylene-2,5-diamine (T-2,5-DA), o -aminophenol (OAP), in-aminophenol (MAP) p-aminophenol (PAP) and p-amino-o- cresol (PAOC) were selected as the object of study. After alkaline-digestio n, hair samples were adjusted to a pH of 12.6 to 12.8, and applied onto an Extrelut column. After 15 min, the components were simultaneously extracted and derivatized with n-hexane including 1% heptafluoro-n-butyryl (HFB) chl oride. Their HFB derivatives within a condensed sample were diluted in ethy l acetate, and analyzed by gas chromatography-mass spectrometry (GC-MS) wit h full mass scanning or selected ion monitoring. For estimating their level s, 2,4,6-trimethylaniline was used as the internal standard. Standard curve s obtained by preparing a 5 cm segment of control hair spiked with authenti c substances were linear, ranging from 0.1 to 4.0 mu g for PPDA and T-2,5-D A, and from 0.01 to 0.4 mu g for GAP, MAP, PAP and PAOC. The coefficient of variation of inter-day precisions (each n = 4) was below 16% for PPDA, bel ow 20% for OAF and PAP and below 24% for T-2,5-DA, MAP and PAOC. These comp onents were detectable even at 6 ng for PPDA, T-2,5-DA, MAP and PAP, 8 ng f or GAP, and 4 ng for PAOC. Recovery percents using this procedure ranged fr om 54 to 86%. By using actual dyed hair samples this method was shown to pr ovide high sensitivity for accurate detection.