Validation of method for the determination of mercury in the auxiliary substances azorubine 21% and azorubine 85% using cold-vapor atomic absorption spectrometry

Abstract

Heavy metals including mercury occasionally appear in pharmaceutical auxiliary substances. Though present in minimal concentrations, control remains crucial due to toxicity. European Commission directives establish permissible mercury limits in food coloring additives like azorubine. Samples underwent microwave acid digestion with specific acid mixtures converting mercury to Hg²⁺ ions, then analysis via cold vapor atomic absorption spectrometry using sodium borohydride reduction. The method was successfully validated and can be applied for the determination of Hg in solid samples of Azorubine 21% and Azorubine 85%, with value of recovery factor of 95% to 104% and 96% to 105%, respectively.