Microspectrophotometric discrimination of single fibres dyed by indigo andits derivatives using ultraviolet-visible transmittance spectra

Single fibres dyed by indigo and its seven derivatives were measured by mic rospectrophotometric examination of transmittance spectra in the ultraviole t-visible region (240-760 nm). Glycerin was the most suitable embedding rea gent for this measurement. Small intra-sample variation of the transmittanc e intensity in single woollen fibres was observed, but relatively large int er-sample variation was observed among the fibres obtained from different a reas in the same textile. There were no differences in the lambda max, lamb da min and the position of shoulders observed in their spectra. This method was applied to the discrimination of single cotton fibres dyed by vat dyes , such as indigo and seven indigo derivatives which had similar structures. On the basis of the ultraviolet-visible transmittance spectra, these sampl e fibres could be distinguished from one another. It is a non-destructive m ethod compared with chromatographic dyestuff extraction methods; furthermor e, utilization of the ultraviolet region gave spectra providing useful info rmation for evaluating fibre evidence.