Investigations to establish whether a link exists between exposure to organic materials in cotton dust and development of byssinosis rely on chemical/chromatographic analysis of cotton dusts and results of bioassays obtained using those same cotton dusts. Pittsburgh investigators found that nickel sieved cotton dust caused greatly reduced physiological responses from exposed guinea pigs compared to exposure to dusts generated from the same material using normal unsieved conditions. This report describes use of our previously reported high-performance liquid chromatographic (HPLC) analytical procedure to examine in a comparative manner the nickel sieved and unsieved cotton dusts. The cotton dust samples that had received the nickel sieve treatment generally showed substantially reduced numbers of components and quantities of UV absorbing materials. The region examined using these HPLC conditions is characteristic of typical tannins and therefore these results may reveal substantially reduced amounts of tannins in nickel sieved cotton dusts.