Beer sample decomposition using a reflux system for the monoelementar determination by F AAS/AES and multielementar determination by MIP OES

Abstract This study describes the development of an analytical method for the analysis of beer samples by atomic spectrometric techniques. The samples were prepared by acid decomposition using a reflux system, and the determinations carried out by F AAS (Fe, Mg and Zn), F AES (Na) and MIP OES (Ca, Fe, K, Mg, Mn, Na, Ni and Zn). The best conditions for sample decomposition were obtained by way of studies using a central rotational compound design: 10.0 mL of degassed beer followed by the addition of 5.0 mL of HNO3 and 2.0 mL H2O2 and a heating step in the digester block at 160 °C for 93 min. The quantification limits of the method were ≤ 0.100 mg L-1 for all the analytes investigated, regardless of the analytical technique used, values below those established by the Brazilian Health Surveillance Agency for Zn and Ni, for example. The comparative study of the different techniques showed that, according to the t-test at a 90% level of confidence, there was no significant difference for the determinations of Fe, Mg, Na and Zn in the beer samples. The sample preparation method was shown to be simple, fast, low-cost and reliable for the analysis of beers by the different atomic spectrometry techniques.