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A new method based on synergism between MW and UV radiation was proposed for chocolate digestion using diluted HNO3 for subsequent determination of As, Cd, Ni and Pb by ICP-MS.

A method is proposed for the determination of selenium at low concentration in coal by collision/reaction cell technology inductively coupled plasma mass spectrometry (CRC-ICP-MS). Samples were decomposed by high pressure microwave-assisted wet digestion (MAWD) using 250 mg of coal, a mixture of 5 mL of 14.4 mol L-1 HNO3 and 1 mL of 40% HF and 70 min of heating program (200 ºC and 40 bar). Hydrogen gas used in the collision/reaction cell was investigated to minimize the argon-based interferences at m/z 77, 78 and 80. The rejection parameter (RPq) and the H2 gas flow rate were set to 0.45 and 4.8 mL min-1 , respectively. The use of H2 in the cell resulted in other polyatomic interferences, such as 76 Ge 1 H + , 79 Br 1 H + and 81 Br 1 H + , which impaired Se determination using 77 Se, 80 Se and 82 Se isotopes, thus Se determination was carried out by monitoring only 78 Se isotope. Selenium determination was performed in certified reference materials of coal (NIST 1635 and SARM 20) and an agreement better than 95% was observed between the results obtained by CRC-ICP-MS and the certified values. Under optimized conditions, the instrumental limit of detection was 0.01 µg L-1 and the method limit of detection was 0.01 µg g-1 , which was suitable for Se determination at very low concentration in coal.

In this study, the microwave-induced combustion (MIC) method was evaluated for the sample preparation of the most consumed mushroom species in Brazil (Champignon, Shiitake, and Shimeji) and further halogen determination by ion chromatography (IC). For this, sample mass, combustion aid mass, and absorbing solution (H2O and 50 mmol·L−1, 100 mmol·L−1, or 150 mmol·L−1 NH4OH) were evaluated. Bromine and iodine concentrations, determined by IC, were lower than the limits of detection (LODs, Br: 6 mg·kg−1 and I: 24 mg·kg−1). Inductively coupled plasma mass spectrometry (ICP-MS) was also used for Br and I determination, and the LODs were lower (Br: 0.066 mg·kg−1 and I: 0.014 mg·kg−1) than those obtained by IC. Concentrations of Cl, obtained by IC, ranged from 523 mg·kg−1 to 13053 mg·kg−1 with LOD of 40 mg·kg−1. In turn, Br and I concentrations, obtained by ICP-MS, ranged from 2.49 mg·kg−1 to 5.50 mg·kg−1 and from <0.014 mg·kg−1 to 0.047 mg·kg−1, respectively. Fluorine concentrations, determined by IC, were always lower than LOD (23 mg·kg−1). The trueness of the proposed methods was evaluated by recovery tests using standard solutions and a reference material (RM NIST 8435). When using the standard solution, recoveries ranged from 95% to 103% for halogen determination by IC and from 105% to 109% for Br and I determination by ICP-MS. When using the RM, recoveries of 102% for Cl by IC and of 87% and 86% for Br and I by ICP-MS, respectively, were obtained.

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Rationale To increase the consumption of egg powder and its fractions a suitable quality control method is required to obtain more information on its nutritional composition. The proposed method enables the quantification of important elements for the functioning of the human organism, such as halogens and sulfur, in egg powder and its fractions. Methods Up to 350 mg of egg powder or its fractions (egg white powder and egg yolk powder) were digested by microwave‐induced combustion using 20 bar pressure of oxygen. The analytes were absorbed in 100 mmol L−1 of NH4OH solution. The determination of halogens (chlorine, bromine, fluorine, and iodine) and sulfur was performed in a single analysis using ion chromatography with conductivity detection coupled to mass spectrometry. Results Using the proposed method, spike recoveries between 99% and 104% for all analytes were obtained, and results agreed with certified values of reference materials (agreements were between 100% and 109%). The relative standard deviations were below 8%. The variation in elemental concentration over a wide range in different fractions (whole egg powder, egg white powder, and egg yolk powder) and different brands was also observed. Conclusions The proposed method provides reliable information about minerals in whole egg powder and its fractions, contributing to better quality control of these products. Because these food products are widely consumed, these results suggest the safe ingestion levels of these elements.

The development of a method for the ultra-trace determination of selenium and tellurium in coal by ICP-MS using microwave-induced combustion for sample preparation.