Simple spectrophotometric determination of urinary albumin by dye-binding with use of bromphenol blue.
This procedure for routine quantification of albumin in urine is based on the dye-binding properties of albumin with bromphenol blue. The absorbance of 100 microL of urine mixed with 3 mL of color reagent is measured against blank reagent at 610 nm after 30 s. Results vary linearly with albumin concentration up to 6 g/L. The reaction is pH independent in the physiological range. It is not subject to substantial interference by uric acid, creatinine, calcium, sodium chloride, or bilirubin. The presence of globulins produces a small positive error. Within-run precision (CV) was 4.8, 1.5, and 0.9%, and day-to-day precision was 11.2, 2.0, and 1.9%, for samples containing albumin at about 0.1, 1.0, and 6.0 g/L, respectively. Results by a radial-immunodiffusion method (x) correlated well with those by the proposed method (y): r = 0.986; y = 0.98x + 0.096; n = 64. The method can also be used to detect globulins, such as Bence Jones protein, by measuring the ratio of the absorbance at 30 min to that at 30 s.
D000293:Adolescent; D000328:Adult; D000419:Albuminuria / Q000652:urine*; D001978:Bromphenol Blue; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D005779:Immunodiffusion; D008297:Male; D008875:Middle Aged; D010636:Phenols; D011786:Quality Control; D012016:Reference Values; D013053:Spectrophotometry
D010636:Phenols; D001978:Bromphenol Blue