Collaborative study of the colorimetric determination of zirconium in antiperspirant aerosols

A previously published method for determining zirconium in antiperspirant aerosols was collaboratively studied by 7 laboratories. The method consists of 2 procedures: a rapid dilution procedure for soluble zirconium compounds or a lengthier fusion procedure for total zirconium (soluble and insoluble compounds), followed by colorimetric determination. The collaborators were asked to perform the following: Spiking materials representing 4 levels of soluble zirconium were added to weighed portions of a zirconium-free cream base concentrate and the portions were assayed by the dilution procedure. Spiking materials representing 4 levels of zirconium in either the soluble or the insoluble form (or as a mixture) were also added to portions of the same concentrate and these portions were assayed by the fusion procedure. They were also asked to concentrate and assay, by both procedured, 2 cans each of 2 commercial aerosol antiperspirants containing zirconyl hydroxychloride. The average per cent recoveries and standard deviations for spiked samples were 99.8-100.2 and 1.69-2.71, respectively, for soluble compounds determined by the dilution procedure, and 93.8-97.4 and 3.09-4.78, respectively, for soluble and/or insoluble compounds determined by the fusion procedure. The average per cent zirconium fouund by the dilution procedure in the 2 commercial aerosol products was 0.751 and 0.792, respectively,with coefficients of variation of 2.94 and 2.53%, respectively. Insufficient collaborative results were received for the fusion procedure for statistical evaluation. The dilution procedure for statistical evaluation. The dilution procedure has been adopted as official first action.