RESUMEN
A simple and automated system based on combustion followed by a pyrohydrolysis reaction was proposed for further halogens determination. This system was applied for digestion of soils containing high (90%) and also low (10%) organic matter content for further halogens determination. The following parameters were evaluated: sample mass, use of microcrystalline cellulose and heating time. For analytes absorption, a diluted alkaline solution (6â¯mL of 25â¯mmolâ¯L-1â¯NH4OH) was used in all experiments. Up to 400â¯mg of soil with high organic matter content and 100â¯mg of soil with low organic matter content (mixed with 400â¯mg of cellulose) could be completely digested using the proposed system. Quantitative results for all halogens were obtained using less than 12â¯min of sample preparation step (about 1.8â¯min for sample combustion and 10â¯min for pyrohydrolysis). The accuracy was evaluated using a certified reference material of coal and spiked samples. No statistical difference was observed between the certified values and results obtained by the proposed method. Additionally, the recoveries obtained using spiked samples were in the range of 98-103% with relative standard deviation values lower than 5%. The limits of quantification obtained for F, Cl, Br and I for soil with high (400â¯mg of soil) and low (100â¯mg of soil) organic matter were in the range of 0.01-2⯵gâ¯g-1 and 0.07-59⯵gâ¯g-1, respectively. The proposed system was considered as a simple and suitable alternative for soils digestion for further halogens determination by ion chromatography and inductively coupled plasma mass spectrometry techniques.