DETERMINATION OF FREE GOSSYPOL IN COTTONSEED AND COTTONSEED MEALS BY 2ND-DERIVATIVE ULTRAVIOLET SPECTROPHOTOMETRY

A new spectrophotometric method for the determination of "free" gossypol in cottonseed and cottonseed meals has been developed. The method involves extraction of free gossypol with aqueous acetone, hydrolysis of the "soluble-bound" forms of gossypol with hydrochloric acid, partitioning of the pure compound into chloroform, and analysis by derivative spectrophotometry. Reaction of the analyte with a chromogenic reagent is not required, since the second-derivative transformation and measurement of the conventional analytical band around 300 nm permits direct quantitation of gossypol in sample extracts. The method was evaluated at concentration levels normally encountered in cottonseed meals. Precision and accuracy data suggested an overall precision of 4.0% and an overall accuracy of 91.2 +/- 3.6%. The new method gave results comparable with those obtained by the official AOCS method, for all but one of the samples analyzed.