COMPARATIVE EXTRACTION METHODS FOR SPECTROPHOTOMETRIC ANALYSIS OF URIC-ACID IN AVIAN EXCRETA

Different extraction techniques were compared in uric acid analysis of avian excreta. These include five extraction reagents (0.1 M sodium h ydroxide, 0.1 M glycine buffer, 0.068 m lithium carbonate, 0.136 M lit hium carbonate and sodium berate buffer, pH 9.1). Each extraction reag ent was used with four excreta sample weights (50, 100, 150 and 200 mg ) for four extraction periods (10, 20, 30 and 40 min) in four extracti on volumes (5, 10, 15 and 20 ml). Extraction with sodium hydroxide gav e lower uric acid concentration; however, glycine buffer extraction ga ve uric acid concentration that was higher (P < 0.05) than extraction with lithium carbonate or sodium berate buffer. Uric acid concentratio n increased with increase in sample weight and decreased with decrease in reagent volume when extracted with glycine buffer. Filtration of s odium hydroxide and glycine buffer extract with 1-kDa low-binding rege nerated-cellulose membrane did not alter uric acid extraction efficien cy from avian excreta. Regardless of length of extraction period or vo lume, the recovery of crystalline uric acid following extraction with lithium carbonate or sodium berate buffer was not different from 100% when 100 mg sample or less was extracted. The optimum extractions cond ition 25 were 100 mg sample in 10 ml and 50 to 200 mg sample in 15 ml 0.068 M lithium carbonate or sodium berate buffer for 10 min at 99 deg rees C.