This is conducted in a laboratory and consists firstly of separating the liquids from the solids in urine. This novel approach will ultimately improve the effectiveness of the current urine drug testing programs. Urine Analysis An Overview Sciencedirect Topics In this reaction the acetoacetic acid in an alkali medium reacts with the sodium nitroprusside producing a magenta coloured complex. . Describe the chemical reactions quality control measures and interpretation of results for urinalysis reagent strip analytes including pH specific gravity protein glucose ketones bilirubin blood nitrites urobilinogen leukocyte esterase. This term is used to describe what happens when excess urine is left on the stick after dipping and so the acid buffer from the reagent in the protein area runs onto the pH area. One promising approach to address this current limitation has been the use of unique oxidation products formed from reaction of drug analytes