Improved method for measuring quinolinic acid in biological specimens.

Abstract A method for the determination of quinolinic acid in liver and urine has been described. The procedure involves extraction of the tissue with perchloric acid and absorption of the quinolinic acid with Norit-A followed by elution with ammonium hydroxide and decarboxylation in glacial acetic acid. The colorimetric method of Waisman and Elvehjem has been modified in order to increase the sensitivity of the method. With the above procedure as little as 20 μg of quinolinic acid can be measured in 25 gm of rat liver and as little as 10 μg of quinolinic acid in 50 ml of urine. We have found this procedure for the measurement of quinolinic acid to be more sensitive, reliable, and faster than the use of ion-exchange or thin-layer chromatography as described by others (8,9). With this assay we have been able to measure changes in the quinolinic acid level of the liver during physiological alterations (starvation and refeeding).