Use of the triiodide–hexadecylpyridinium chloride micellar system for the kinetic determination of molybdenum(VI)

Abstract

The associate formed by triiodide ion and hexadecylpyridinium chloride (cetylpyridinium chloride; CPC) micelles was used to enhance the kinetic spectrophotometric determination of Mo^VI by its catalytic action on the oxidation of iodide with hydrogen peroxide in an acidic medium. The reaction rate was monitored at 500 nm, the maximum absorption wavelength of the l₃^––CPC associate. The micellar medium allowed the determination of Mo^VI at concentrations between 2 and 150 ng ml^–1, with a detection limit of 1.3 ng ml^–1(i.e., about 6–8 times lower than those of methods implemented in aqueous media). The relative precision achieved for 80 ng ml^–1 of Mo^VI was 2.6%. The selectivity towards interferents, yielding yellowish solutions, was significantly enhanced. The proposed method was applied to the determination of Mo in aqueous extracts of soil samples with no prior separation.