Application of Thin Layer Chromatography Using Monochromatic Light Irradiations in Forensic Examination : Discrimination of Ballpoint Pen Inks, Gel Pen Inks and Hair Dyes

法科学における着色剤の検査には従来より薄層ｸﾛﾏﾄｸﾞﾗﾌｨｰ(TLC)が多用されてきた｡本研究では着色剤に対する TLC 分析の識別能力と検出感度の向上を目的として､530nm と 450nm の単色光を照射し､ｸﾛﾏﾄｸﾞﾗﾑを観察･記録する方法を検討した｡油性黒色ﾎﾞｰﾙﾍﾟﾝｲﾝｸ､黒色ｹﾞﾙﾍﾟﾝｲﾝｸおよび黒色染毛剤で染色された毛髪試料に本法を応用した｡実験したﾎﾞｰﾙﾍﾟﾝｲﾝｸ16種はすべて識別でき､ｲﾝｸの線の長さとして1mm で検出可能であった｡ｹﾞﾙﾍﾟﾝｲﾝｸについては実験した10種類のうち､不溶性顔料を用いていると思われる3種類は抽出されなかったが､他の7種類はすべて識別された｡検出限界は､蛍光を発する試料ではｲﾝｸ線の長さとして1mm､蛍光を発しないものは5mm であった｡12種類の染毛剤で染色された毛髪試料について実験した結果､2組の試料を除く他8種類はすべて識別可能であり､検出に必要な毛髪の長さは､1本の毛髪として6cm であった｡
Thin layer chromatography(TLC)has been used for the forensic examination of colorants. The aim of this study is to improve the discriminatory power and the detection limits for TLC by using 530nm and 450nm monochromatic lights for observing and recording chromatograms through cut filters. This method was applied to black ballpoint pen inks, black gel pen inks and black hair dyes. Among the sixteen ballpoint pen inks examined here, all the samples were discriminated with the detection limits of 1mm-long ink lines. Although three gel pen inks, which may have used insoluble pigments, could not be extracted, seven other samples were discriminated each other. For the gel pen inks that radiate fluorescence, the detection limits were 1mm -long ink lines, and for those with no fluorescence, the detection limits were 5mm. Human hair samples dyed with twelve commercially available black hair dyes were effectively discriminated with the exception of two pair of samples. The detection limits for the single hairs were 6cm.