FEASIBILITY OF Br, Cl AND I DETERMINATION IN HONEY USING PLASMA-BASED TECHNIQUES AFTER MICROWAVE-ASSISTED WET DIGESTION IN A SINGLE REACTION CHAMBER WITH HYDROGEN PEROXIDE IN ALKALINE MEDIUM

In this work, a green digestion method using only H2O2 in an alkaline medium with a single reaction chamber system (SRC-UltraWave™) was evaluated for honey digestion and for further determination of Br, Cl and I by inductively coupled plasma (ICP)-based techniques. Hydrogen peroxide can also oxidize organic compound with the advantage of the production of water as one of the main product. Honey is a complex carbohydrate matrix that can be used as a monitor of environmental pollution. Additionally, honey is considered the only sugar, in concentrated form, available to man in some parts of the world. In this sense, halogen determination in honey is important to evaluate aspects related to environmental and nutritional concerns. Important parameters such as temperature and pressure of SRC system, concentration and volume of H2O2, sample mass and volume of NH4OH were evaluated to produce digest with the minimum concentration of residual carbon (RC). Determination of Br and I were determined by inductively coupled plasma mass spectrometry (ICP-MS), and C and Cl determination were carried out using inductively coupled plasma optical emission spectrometry (ICP-OES). After optimization of the parameters digestion was performed using up 500 mg of honey, 8 mL of H2O2 mixed with 500 μL of NH4OH and maximum temperature and pressure of 270 °C and 199 bar, respectively. Carbon-related matrix interferences in ICP-MS analysis were evaluated for determination of Br and I. Using the optimized conditions, the digests presented a concentration of residual carbon (RC) lower than 220 mg L−1, that did not cause interferences in determination by ICP-OES and ICP-MS. Accuracy was evaluated using certified reference materials NIST 8433 (corn bran) and NIST 1568a (rice flour), and also by comparison between values obtained using proposed method and those obtained by MIC. Significant differences were not observed by comparison between the results of the proposed method and reference values of CRMs and MIC. Limits of detection obtained by the proposed method were 10 mg kg-1 for Cl using ICP-OES and 0.03 and 0.005 mg kg-1 for Br and I (ICP-MS), respectively.The proposed method was suitable for determination of Br, Cl and I in honey samples in consonance with green sample preparation.