Abstract

REYES-SALAS, E. Octavio et al. Polarographic determination of metal pollutants for quality control technician grade phosphoric acid used in the production of food grade phosphate. Rev. Int. Contam. Ambient [online]. 2014, vol.30, n.1, pp.113-120. ISSN 0188-4999.

Phosphates are more versatile additives in food industry, among other applications are used as preservatives, pH buffers, antioxidants, emulsifiers, acidifying agents, disper-sants, etc. The phosphates are derived from phosphoric acid and this in turn is obtained in large quantities from a mineral known as fluorapatite; by the nature of the ore which gives rise to the phosphoric acid is important the analysis of various metal species that may be toxic to humans. Lead, cadmium and arsenic are present in the fluorapatite; in the same way may be present trace elements such as copper, zinc and iron if consumed in excess daily requirements can be harmful to health. In this paper we analyzed four samples of technical grade phosphoric acid (used for the manufacture of food grade phosphates) by differential pulse polarographic technique, employing HNO₃/KNO₃ 0.1 mol L^-1 with a three-electrode system. The detection limits found for As^m, Pbⁿ, Cdⁿ, Cuⁿ, Znⁿ, and U^VI (as (UO₂)^2-) were below the limits required by the international food additives rules and regulations. We identified and quantified Cdⁿ and Znⁿ in all samples analyzed, Cuⁿ in two of the samples and As^m and U^VI in one sample each one.

Keywords : phosphoric acid; phosphates; electrochemical study; differential pulse polarography; quality control; food additives.