Identification of allantoin, uric acid, and indoxyl sulfate as biochemicalindicators of filth in food packaging by LC

A liquid chromatographic (LC) method was developed for the determination of allantoin, uric acid, and indoxyl sulfate in mammalian urine contaminated packaging material including paper bagging, corrugated cardboard, graybeard , and burlap bagging. The procedure involves solvent extraction and isolati on of the 3 analytes by reversed-phase LC with ultraviolet detection at 225 nm for allantoin and 286 nm for uric acid and indoxyl sulfate. The composi tion of authentic mammalian urine such as mouse, rat, cat, dog, and human w ere also determined with regard to the 3 compounds of interest. A linear co ncentration range of 0.11-20.4, 0.02-10.0, and 0.04-30.0 mug/mL was obtaine d for allantoin, uric acid, and indoxyl sulfate, respectively. Limits of de tection (LOD) and quantitation (LOQ) were 0.0104 and 0.0345 mug/mL for alla ntoin; 0.0018 and 0.0060 mug/mL for uric acid; and 0.0049 and 0.0165 mug/mL for indoxyl sulfate, respectively. Interday relative standard deviation va lues for a mixture of standard allantoin, uric acid, and indoxyl sulfate (n = 5) were 0.97, 0.80, and 0.94%, respectively. Analyte composition for 5 t ypes of authentic mammalian urine varied from 0.14-6.88 mg/mL allantoin; 0. 08-0.57 mg/mL uric acid; and 0.03-0.78 mg/mL indoxyl sulfate. Analyte conte nt for 8 samples including 2 samples each for paper, cardboard, graybeard, and burlap bagging each contaminated with mouse or rat urine ranged from < LOD to 4598 mug/gm allantoin; < LOD to 202 mug/gm uric acid; and 17.5 to 61 6 mug/gm indoxyl sulfate. Recoveries of allantoin, uric acid, and indoxyl s ulfate from 11 fortified samples (4 types) for both mouse and rat urine ran ged from 28.2 to 114.1% for allantoin; 32.6 to 123.4% for uric acid; and 52 .6 to 118.2% for indoxyl sulfate.