Estimation of Dyes in Solution by Transmission Measurements

The estimation of dyes in solution by absorption spectrophotometry is reviewed with special emphasis on the use of such techniques by manufacturers and users to compare the strengths of commercial dyes. The theoretical basis of measurements of absorbance or transmittance is outlined. Comments are made on recommended procedures with regard to deviations from ideal behaviour and the sources of error that may arise in practice. Specific test conditions that have been suggested for the estimation of dyes from various application classes are summarised. Techniques of extraction of dyes from textile substrates are included, because these often precede spectrophotometric measurements in quantitative analysis and the investigation of dyeing mechanisms