title: A highly sensitive colorimetric determination of serum zinc using water-soluble pyridylazo dye.
abstract: A colorimetric method for precise and accurate determination of zinc in serum is presented. Only 0.3 ml of sample is necessary, because of the use of a new, highly sensitive reagent, 2-(5-bromo-2-pyridylazo)-5-(N-n-propyl-N-3-sulfopropylamino)-phenol (epsilon 554nm = 1.3 X 10(5) 1 . mol-1 . cm-1), which is water-soluble and has long-term stability. Interference of iron and copper in serum can be removed by co-precipitation of the iron fluoride complex with trichloroacetic acid precipitated proteins and the copper dithiocarboxy sarcosine complex, respectively. Within-run and day-to-day precision (CV) are in the range of 0.3-3.5% and 1.9-3.1%, respectively, depending on the serum zinc content. A good correlation (r = 0.98, p less than 0.05) was obtained between this method and atomic absorption spectrometry. In contrast to previous colorimetric methods, the present method does not involve heating, extraction with organic solvents, or a cyanide masking system.
mesh_terms: D001391:Azo Compounds; D011232:Chemical Precipitation; D003124:Colorimetry / Q000379:methods*; D003300:Copper / Q000097:blood; D006801:Humans; D007202:Indicators and Reagents; D007501:Iron / Q000097:blood; D013054:Spectrophotometry, Atomic; D013057:Spectrum Analysis; D015032:Zinc / Q000097:blood*
chemical_list: D001391:Azo Compounds; D007202:Indicators and Reagents; D003300:Copper; C034322:2-(5-bromo-2-pyridylazo)-5-(N-n-propyl-N-3-sulfopropylamino)phenol; D007501:Iron; D015032:Zinc