Determinação de halogênios em mel após decomposição com peróxido de hidrogênio usando sistema de alta pressão

Abstract

In this work the sample preparation method for honey decomposition using H2O2 in alkaline medium at high pressure system for further determination of F, Cl, Br and I was evaluated. In this way, some parameters such as temperature, volume of H2O2, sample mass and volume of NH4OH were evaluated to produce digests with the minimum concentration of residual carbon. After optimization of the parameters for decomposition, the C interference by inductively coupled plasma mass spectrometry (ICP-MS) were evaluated for further determination of Cl, Br and I. Fluorine was determined by ion selective electrode. Decomposition with H2O2 in alkaline medium using high pressure system was carried out using masses up to 500 mg of honey, 8 mL of H2O2, 550 μL of NH4OH and temperature of 250 ºC. The final digests obtained by the proposed method have shown a concentration of C lower than 200 mg L-1 which represent approximately 3% of total C in honey. The accuracy of the proposed method was evaluated using recovery, two reference materials (NIST 8433 - corn bran reference material and NIST 1568a - rice flour reference material) and by comparison between values obtained using proposed method and those obtained by MIC. The obtained results by accuracy tests were considered. Limits of quantification (LOQ) obtained for halogens by the proposed method were 8 μg g-1, 23 μg g-1, 0,07 μg g-1 e 0,01 μg g-1 for F by ISE, Cl, Br and I by ICP-MS, respectively.