Determination of zinc in cassava based polymeric materials

Abstract

The current trends in biodegradable food packaging include the use of materials such as biopolymers which should be free of toxic metals to ensure their quality and use in multiple applications. However, these samples can contain zinc given its presence in the materials used to make them. In this study, a method to determine the concentration of zinc (Zn) in thermoformed and biodegradable flexible films samples based on Cassava and in their raw materials (flour, starch and fique) using flame-atomic absorption spectroscopy is described. Prior, an acid digestion with nitric acid under reflux was required. The method was standardized by means of the evaluation of statistical parameters. The method was sufficiently lineal ( R2 = 0.999) in a working range from 0.1 to 1.0 mg Zn/L with detection and quantification limits of 0.03 and 0.82 mg/L, respectively. The method was found to be precise and accurate, and could therefore be used to measure Zn content at levels well below safe limits.The precision of the method was evaluated using intermediate precision and repeatability which showed coefficients of variation less than 6.7% and 4.7%, respectively. The percentages of recovery ranged from 96.5% to 98.2%. The method was successfully applied for the determination of Zn in the studied biopolymers samples and the results obtained support the method’s suitability for determining the presence of the metal. Zinc concentrations in thermoformed, flexible films and flour were below 2.36, 2.14 and 2.01 mg/L, respectively, indicating that these polymers could be used for food containers.