Automated analysis of flour extracts for uric acid and its correlation with degree of insect defilement

An automated method is described for quantitating uric acid in a sodium acetate extract of flour. The difference in color intensity developed in a flour extract treated with the enzyme uricase and one that is not treated is measured spectrophotometrically. A mean recovery of 97.1% was obtained for 50 g flour samples spiked with 1 mg uric acid. The method can measure as little as 50 micrograms uric acid in 50 g flour and is used to establish a correlation between the uric acid in the flour and the number of insect fragments and excreta pellets present. A 42-data point least squares straight line having a slope of 1.62 and a correlation coefficient of 0.750 (99.9-100% valid) is used to establish the relationship of uric acid to insect defilement.