In this work, solutions of oxidant salts were evaluated as alternative to nitrate solution for the ignition step in microwave-induced combustion (MIC) method. Aqueous solutions of KClO4, K2Cr2O7, KMnO4 and K2S2O8 in several concentrations were evaluated and it was observed that the ignition was dependent on the concentration and type of igniter solution. Moreover, it was possible to observe that ignition and combustion times are not related with sample mass, which was confirmed by evaluating sample masses ranging from 100 to 500 mg of whole milk powder. Certified reference materials were digested using K2Cr2O7 as igniter solution and digests analyzed by inductively coupled plasma optical emission spectrometry (ICP OES), with good agreement to certified values. The obtained results suggest that MIC can be performed using solutions of oxidants salts. In addition, the proposed study contributed to a better undestanding and explaining the ignition with microwaves.
Keywords:
microwave-induced combustion; microwave ignition; oxidants salts; sample preparation; sample digestion
