PAR

- Overview
  - PAR is a metal indicator and colorimetric reagent for heavy metal ions. The solubility of this reagent in water (5 mg per 100 ml at 10°C) is higher than that of PAN. PAR is slightly soluble in alcohol. The aqueous solution is red at pH 5.5 or less, orange at pH 6-12.5, and red at pH 13 or higher. Its proton dissociation constants are reported to be pKa1(NH+)=3.1, pKa2(p-OH)=5.6 and pKa3(o-OH)=11.9 (m=0.2). PAR forms complexes with various metal ions that can be extracted with chloroform.
    
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- Properties
  - Categories
    
    Ion Analysis
    
    CAS Number
    
    1141-59-9
    
    Molecular Formula
    
    C11H9N3O2
    
    Molecular Weight
    
    215.21
    
    Appearance
    
    Yellowish orange or orange-red powder
    
    Storage
    
    ambient temperature, protect from metal
    
    Shipping
    
    ambient temperature
    
    * For research use only
- Reference
  - 1) W. J. Geary, et al., The Metal Complexes of Some and Azomethine Dyestuffs Part I. Spectra in Water, and in Dioxan/Water in the Wavelength Range 320-600 mμ. Anal Chim Acta. 1962;26:575-582.
    
    2) R. M. Dagnall, et al., Determination of Lead with 4-(2-Pyridylazo)-resorcinol-I Spectrophotometry and Solvent Extraction. Talanta. 1965;12:583-588.
    
    3) G. Pilloni, et al., Spectrophotometric Determination of Diethyllead and Diethyltin Ions with 4-(2-Pyridylazo)-resorcinol. Anal Chim Acta. 1966;35:325-329.
    
    4) L. Sommer, et al., Complexation of Aluminium, Yttrium, Lanthanum and Lanthanides with 4-(2-Pyridylazo)Resorcinol (PAR). Talanta. 1967;14:457-471.
    
    5) R. Sawyer, Determination of Dialkyltin Stabilisers in Aqueous Extracts from PVC and Other Plastics. Analyst. 1967;92:569-574.
    
    6) Z. Kleckova, et al., Spectrophotometric Study of Complex Equilibria and Determination of Lead(II) with 4-(2-Pyridylazo)resorcinol. Collect Czech Chem Commun. 1978;43:3163-3178.
    
    7) A. Rios, et al., New Configuration for Construction of pH Grandients in Flow Injection Analysis. Anal Chem. 1986;58:663-664.

MSDS

PAR

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