Clinical Chemistry · 1977 · 35 citations · 0 references
Life SciencesBiochemistryClinical BiochemistryFood AnalysisProtein BiochemistryColor AnalysisProtein AnalysisProtein CharacterizationProtein SeparationAbsorptivityColorimetric ScreeningProtein Content AnalysisProtein Content DeterminationQuantitative DeterminationUrine Protein Testing
Total urinary protein is rapidly precipitated at room temperature by tannic acid. The tannic acid/protein precipitate, dissolved in aqueous triethanolamine/ferric chloride solution, gives a purple-violet color of high absorptivity. Absorbance at 510 nm is linearly related to concentration from 0.05 to 1.50 A for a protein content of 0.05 to 1.50 g/liter, and less than 5 mg/liter can be detected. The CV and analytical recovery ranged from 0.5 to 1.8% and 98 to 103%, respectively. Nonprotein urinary constituents do not interfere.