Determination of Halogens by Ion Chromatography in Edible Mushrooms after Microwave-Induced Combustion for Sample Preparation.

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.

Ion chromatography coupled to mass spectrometry as a powerful technique for halogens and sulfur determination in egg powder and its fractions.

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 NH4 OH 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.

Green and efficient sample preparation method for the determination of catalyst residues in margarine by ICP-MS.

Responding to the need for green and efficient methods to determine catalyst residues with suitable precision and accuracy in samples with high fat content, the present work evaluates a microwave-assisted ultraviolet digestion (MW-UV) system for margarines and subsequent determination of Ni, Pd and Pt using inductively coupled plasma mass spectrometry (ICP-MS). It was possible to digest up to 500mg of margarine using only 10mL of 4molL-1 HNO3 with a digestion efficiency higher than 98%. This allowed the determination of catalyst residues using the ICP-MS and free of interferences. For this purpose, the following experimental parameters were evaluated: concentration of digestion solution, sample mass and microwave irradiation program. The residual carbon content was used as a parameter to evaluate the efficiency of digestion and to select the most suitable experimental conditions. The accuracy evaluation was performed by recovery tests using a standard solution and certified reference material, and recoveries ranging from 94% to 99% were obtained for all analytes. The limits of detection for Ni, Pd and Pt using the proposed method were 35.6, 0.264 and 0.302ngg-1, respectively. When compared to microwave-assisted digestion (MW-AD) in closed vessels using concentrated HNO3 (used as a reference method for sample digestion), the proposed MW-UV could be considered an excellent alternative for the digestion of margarine, as this method requires only a diluted nitric acid solution for efficient digestion. In addition, MW-UV provides appropriate solutions for further ICP-MS determination with suitable precision (relative standard deviation < 7%) and accuracy for all evaluated analytes. The proposed method was applied to margarines from different brands produced in Brazil, and the concentration of catalyst residues was in agreement with the current legislation or recommendations.