Use of indirect multiple linear regression for multicomponent dye analysis in a leather tanning bath

A spectrophotometric method for the simultaneous determination of dyes with spectral interaction in three-colour baths by use of multiple linear regression with indirect calibration has been developed. This method discretely allows the components of the dyeing bath to be quantified with errors of less than 3% and within 1–2 min of sampling. The method has been applied to monitor the dyeing of chromium-tanned bovine leather splits subjected to various retanning procedures.