Sorption and Determination of Vanadium(IV, V) and Mercury(I, II) as Their Colored Complexes of Organic Reagents

Abstract

The development of methods for the determination of metal ions by color reactions with organic reagents using diffuse reflectance spectrometry or visually after the sorption of their anionic complexes on an anion exchanger has considerable promise. The use of reasonably selected anionic complexes, the introduction of masking complexing agents, and the control of pH at the steps of sorption and determination provide a high sensitivity and selectivity of determination. We studied the sorption of anionic Zn, Pb, Cd, Hg(II), U(IV), Th, and Mo(IV) complexes of inorganic and organic ligands on fibrous materials filled with anion exchangers and their reactions in the solid phase with organic reagents. We revealed the dependences of the analytical signals of complexes on the concentration of anions in the solution and the stability of anionic complexes and the effect of these factors on the total and separate determination of metal ions. In the sorption of Cd, Pb, and Hg from solutions containing , Cl – , J – , , S 2 , SCN – , CH 3 COO – , tartrates, thiourea, nitrilotriacetic acid (NTA), or ethylenediaminetetraacetic acid (EDTA), thiosulfates and iodides were found to be significant in the reactions with dithizone or 4-(2-pyridylazo)resorcinol (PAR). The total of the three elements can be determined with dithizone in a 0.01 M KI solution; the total of cadmium and lead in the presence of mercury can be determined with PAR in an S 2 or J – solution; these elements could not be determined separately. It is preferable to determine mercury with dithizone after sorption from a 10 –4