QUANTITATIVE-DETERMINATION OF POLYCARBOXYLIC ACIDS ON COTTON FABRICS BY NIR

Cotton fabric can be treated with a number of chemical agents that imp art smooth-drying properties; the most common of these are methylol de rivatives of cyclic ureas. On storage, finishes from these agents slow ly but continuously release formaldehyde which has been identified as a probable human carcinogen. The nonformaldehyde containing polycarbox ylic acids such as butanetetracarboxylic acid (BTCA) or citric acid, c an be used to impart smooth-drying properties to cotton fabrics with g ood strength retention. However, these compounds and cellulose contain only carbon, hydrogen and oxygen, so there is no readily available me thod for the quantitation of the polycarboxylic acid on cotton. From i nfrared spectra, carbonyl absorption at 1726 cm-1 has been used to det ermine the amount of BTCA on cotton fabric with some success. However, only a small amount of sample is used (1-2 mg) and sample preparation is labor intensive and time consuming. Near infrared spectroscopy off ers the advantages of larger sample size with rapid and simple sample preparation. A method was developed for obtaining a useful calibration equation when no wet chemical reference method is available.