Spectrophotometric correction for bile pigments in the thiobarbituric acid test for malondialdehyde-like substances in plasma.

A simple method is proposed to improve specificity when estimating malondialdehyde-like components of plasma thiobarbituric acid-reactivity, especially with regard to the considerable contribution of bilirubin. The spectrophotometric method comprises measurement of A485, A532 and A560 instead of only A532. A correction formula is then applied to calculate the portion of the A532 which originates from malondialdehyde-like substances. Using this method, normal values for malondialdehyde average 0.84 mumol/l.