UV–vis absorption spectra in suitable solvent were
recorded using TECHCOMP UV–visible spectrophotometer (UVVIS 8500). The amount of dye on the fabric was determined by
extracting the dye in pyridine–water (1:1) at 60 8C [13] for 1 h
and subjecting it to optical density measurement using Lambert
Beer’s law with respect to lmax = 428 nm of cumin dye. Plotting
of optical density values on the calibration curve, gives their
respective concentrations on silk fabric which can be further
calculated in terms of g of dye/100 g of fibre (silk) or mg/g of
fibre (silk) .