Analytical Application of some Chemical Modifiers in Atomic Absorption Spectrometric Investigation and Determination of Mn(II) and Mn(VII)

Abstract

The interfering effects of a range of cations, acids and organic compounds on the absorption signal of manganese(II) and manganese(VII) were studied in different media under diverse flame profile of different observation heights and fuel flow rates. The signal response of Mn(II) and Mn(VII) is slightly changed under different flame conditions, whereas it is markedly affected in the presence of concomitants. Several chemical modifiers were successfully applied for controlling such effects. Of these, boric acid, lanthanum chloride, strontium chloride, ammonium chloride and aluminium chloride were found to be effective as inorganic chemical modifiers in eliminating specific interferences on Mn(II) and Mn(VII) encountered from inorganic addenda. A combination of boric acid and strontium chloride, 500 ppm each, was able to overcome the potential effects of all inorganic interferences studied. Butylamine and piperidine were also used as excellent chemical modifiers organic reagents for controlling inorganic and organic interferences on manganese. The mechanism of the interfering effects and the releasing action is discussed which is based on masking the interferent(s) with the inorganic reagent(s) through the formation of refractory species, whereas the organic reagent(s) protect(s) the analyte by forming an easily dissociated complex in the flame. A procedure was described for precise determination of manganese in synthetic mixture and some manganese complexes.