Development of an Alkaline Method for the Determination of Cu, Mo, and Zn in Beef Samples

Abstract

An alkaline sample treatment using tetramethylammonium hydroxide was optimized and validated for the determination of Cu, Mo, and Zn in beef samples from Uruguay, aiming to contribute to the food quality evaluation of this product. The optimization of the developed method was performed by means of multivariate experiments. Copper and Zn were determined by flame atomic absorption spectrometry and Mo was determined by electrothermal atomic absorption spectrometry. The proposed method consisted of adding 5.0 mL of ultrapure water to 0.25 g of the sample, followed by 1.5 mL of tetramethylammonium hydroxide 25% w w−1 and 60 min at 85 °C in a water bath. After centrifuging, the obtained solution can be used for the analytical determinations of the three elements. Certified reference materials were analyzed and a comparison with microwave-assisted acid digestion was performed to guarantee reliability. At the 95% significance level, the obtained results were statistically equivalent to the certified values and to those obtained by total acid digestion for all the studied elements. Analytical precision expressed as relative standard deviation was less than 8% in all cases. Copper, Mo, and Zn were determined in Uruguayan beef samples using the proposed alkaline method. Besides, novel information concerning Mo levels was presented in this work.