Department of Colour Chemistry and Dyeing, University of Leeds Leeds LS2 9JT UK.
Int J Cosmet Sci. 1997 Feb;19(1):1-14. doi: 10.1046/j.1467-2494.1997.171752.x.
Untreated and bleached hair samples were analysed by FTIR spectroscopy. Cysteic acid and cysteine-S-thiosulphate were analysed by different data manipulations and various sampling techniques. Single-fibre analysis was achieved using the IR-microscope attachment to the FTIR instrument (transmission mode). An ATR diamond crystal was also used for both single fibres and tresses; this sampling technique was compared to a contact sample ATR cell based on a ZnSe crystal. The microscope was found to be very useful for the analysis of small portions of hair fibres; the effect of weathering along the length of the fibres and the extent of variability among the single fibres was assessed by this technique. The results clearly show a trend in the cysteic acid content increasing from the mid-point to the tip; it was found that hair samples are very heterogeneous. A standard variation of up to 11% is reported for the mean value of the intensity of absorption of cysteic acid in untreated fibres belonging to the same tress sample. The value of the variation decreases when the tress is bleached -- the longer the bleaching process the lower the value of the standard variation (4.5% for hair fibres bleached for 60 min using hydrogen peroxide). The contact sample ATR cell gave poor reproducibility as only poor sample-crystal contact was achieved and the level of noise recorded was too high to allow accurate detection. However the ATR diamond crystal was found to give sensitive and reproducible spectra since much higher levels of transmittance were achieved (better sample-crystal contact); this technique allowed measurements of groups of seven to nine hair fibres at once, but did not provide reproducible spectra of single fibres. Different data manipulations have been assessed; these include derivatization and calculation of peak heights and areas (ratioed by the intensity of absorption of the peaks chosen as internal standards to the amide III 1232--1242 cm-1 and CH2 stretching 1451 cm-1), normalization, averaging spectra and spectral subtraction.
未经处理和漂白发样通过傅里叶变换红外（FTIR）光谱进行分析。半胱氨酸磺酸和半胱氨酸-S-亚磺酸盐通过不同的数据处理和各种采样技术进行分析。单纤维分析使用 FTIR 仪器的红外显微镜附件（透射模式）进行。ATR 金刚石晶体也用于单纤维和发束；这种采样技术与基于 ZnSe 晶体的接触式样品 ATR 细胞进行了比较。显微镜非常适用于分析头发纤维的小部分；通过该技术评估了纤维长度上的风化效果以及单纤维之间的可变性程度。结果清楚地表明，半胱氨酸磺酸的含量从中间点到尖端呈增加趋势；发现头发样品非常不均匀。报告了未处理纤维中半胱氨酸磺酸吸收强度的平均值的标准变化高达 11%，属于同一发束样品。漂白时，标准变化值降低，漂白过程越长，标准变化值越低（用双氧水漂白 60 分钟的头发纤维为 4.5%）。接触式样品 ATR 细胞的重现性较差，因为仅实现了较差的样品-晶体接触，并且记录的噪声水平太高，无法进行准确检测。然而，ATR 金刚石晶体被发现可以提供敏感且可重现的光谱，因为实现了更高的透过率水平（更好的样品-晶体接触）；该技术允许一次测量七到九条头发纤维，但不能提供单纤维的可重现光谱。评估了不同的数据处理；这些包括衍生化和峰高和面积的计算（通过选择作为内标的峰的吸收强度与酰胺 III 1232-1242cm-1 和 CH2 拉伸 1451cm-1 的比值，以及与酰胺 III 1232-1242cm-1 和 CH2 拉伸 1451cm-1 的比值），归一化，平均光谱和光谱减法。
