A Kinetic Study of the Elimination of Salicylate in Man

Chemical methodsA modification of the method of Brodie, Udenfriend & Coburn (1944) was used for the determination of salicylic acid and salicyluric acid in urine." Total salicylate " in urine.The urine was hydrolysed by heating 4 ml.with 2 ml. of 12 N-sulphuric acid in an autoclave at 1150 C for 3 hr.The hydrolysate was diluted to 25 ml.with water and 4 ml. of this solution was extracted with 25 ml. of chloroform; 20 ml. of the chloroform were filtered and shaken with successive 5-ml.volumes of ferric nitrate solution (75 mg/100 ml.) until the colour of the ferric nitrate solution remained unchanged.The ferric nitrate solutions were combined, the total volume was noted and the extinction was determined at 530 mit.Appropriate standard solutions of salicylic acid were treated similarly.Salicylic acid and salicyluric acid in urine.The urine was hydrolysed by heating 2 ml. with 1 ml. of 8 N-sulphuric acid in a boiling-water bath for 1 hr.This procedure hydrolyses salicylic and salicyluric acid glucuronides to their respective acids without appreciably hydrolysing salicyluric acid to salicylic acid.The hydrolysate was successively extracted first with 25 ml. of carbon tetrachloride and secondly with 25 ml. of chloroform, for the determination of salicylic and salicyluric acids respectively.The carbon