Chemical Analyses of Washed,Bleached,and Scoured and Bleached Cotton Fiber

Abstract

The chemical compositions of four cottons from a 1982 washed cotton study (MQ- 111) conducted by the Industry/Government/Union Task Force for Byssinosis Pre vention were established by proximate and elemental analyses. The four cotton samples were an unwashed control grown in Mississippi and the corresponding washed, bleached, and scoured/bleached processed cottons. The proximate analyses consisted of serial solvent extractions that furnished data on moisture, water extractables, ethanol extractables, ethanolamine extractables, cellulose, and insoluble residue. Ash produc tion was also measured for the four cotton lint samples. Elemental analyses were performed by x-ray fluorescence for potassium, calcium, magnesium, silicon, phos phorus, and sulfur, and by Kjeldahl analysis for nitrogen. The analyses demonstrate that the water wash and the scouring procedure are responsible for substantially in creasing the purity of the cotton fiber. The level of water extractables was reduced by the water washing process, while the level of ethanolamine extractables was reduced by the scouring process. The washed cotton sample contained much smaller amounts of potassium and magnesium compounds than the unwashed control. Ash was reduced to approximately the same level by each of the washing processes.

The nitrogen and calcium contents dropped steadily with increasing severity of processing conditions. The changes in chemical composition of cotton lint on pro cessing are related to the layered structured of the cotton fiber. The Cotton Quality Research Station, USDA, and the Division of Respiratory Disease Studies, NIOSH, have determined the effects that dusts from these cottons have on pulmonary function in a group of human volunteers through measurements of the change in forced ex piratory volume in one second (FEV₁) on exposure to dust generated by carding the cotton samples. All three processed cottons were considerably less active than the unwashed control. Many of the chemical composition parameters showed a marked decrease with water washing alone.