Preparo de amostras de carnes em micro escala para determinação de metais por técnicas de Espectrometria Atômica

Abstract

New analytical methodologies have been developed for determination of metals in meats by spectrometric techniques, involving practicality and speed from the sample preparation to analysis, in order to monitor and certify the quality of these products have been widely consumed by the population. Therefore, in this work, we have developed procedures for microscale sample preparation for determination of metals by Atomic Spectrometry techniques (F AES and F AAS), aiming the determination of Na and K through microdigestion with HNO3, and of Mg and Zn through microsolubilization in alkaline medium. The accuracy of the microdigestion method proposed for determination of Na and K was verified by comparing of the results with two other methods of sample preparation (TMAH and formic acid), as well as the use of different certified reference materials (CRMs). For the quantification of Mg and Zn, the accuracy of the proposed methodology, based on a microsolubilizaçãoin alkaline medium, was performed by analysis of several CRMs. By comparing the results obtained for Na e K in processed samples, which were prepared in different means and analyzed by F AES and F AAS, it was verified that these were not significantly different at a confidence level of 95 % with the application of statistical test t-Student. For the results of Mg and Zn, the concentrations found in three CRMs presented values with 95 % agreement with the certified values. Limits of detection (LODs) of 40 mg L-1 for Na and 37 mg L-1 for K were obtained by microdigestion. Lower LODs values were obtained for both elements through the use of alkaline microsolubilization with TMAH, and for Na and K the LODs were 29 and 23 mg L-1, respectively. The Limits of detection found for Mg and Zn were also low, proving the high sensitivity of the method of the analysis proposed, with LODs of 12 mg L-1 for Mg and 92 mg L-1 for Zn. The proposed methodologies (Microdigestion and Microsolubilization) were presented as simple procedures, requiring micro amounts of samples and reagents, proving to be suitable to prepare samples for subsequent determination of the respective elements by atomic spectrometry techniques.