Influence of bilirubin on the determination of acid phosphatase in serum.
Bilirubin interferes greatly in the continuous measurement of acid phosphatase, using alpha-naphthyl phosphate as substrate and diazotized 2-amino-5-chlorotoluene (Fast Red TR) as the colorimetric reagent. Fast Red TR and the so-called "direct" (but not "indirect") bilirubin form a coloured azo-compound which absorbs light above 480 nm. Negative absorbance changes are observed at 405 nm, which is used in the determination of acid phosphatase. This leads to apparently negative activities.
D000135:Acid Phosphatase / Q000097:blood*; D001663:Bilirubin / Q000097:blood*; D003124:Colorimetry; D006801:Humans; D007202:Indicators and Reagents; D013053:Spectrophotometry
D007202:Indicators and Reagents; D000135:Acid Phosphatase; D001663:Bilirubin