Feasibility of ultra-trace determination of bromine and iodine in honey by ICP-MS using high sample mass in microwave-induced combustion

• Published in: Analytical and bioanalytical chemistry 2015-10, Vol.407 (26), p.7957-7964
• Main Authors: Costa, Vanize C, Picoloto, Rochele S, Hartwig, Carla A, Mello, Paola A, Flores, Erico M. M, Mesko, Marcia F
• Format: Article
• Language: English
• Subjects: alkali treatment; ammonium hydroxide; Analytical Chemistry; Biochemistry; Biological samples; Bisphenol A; Blood diseases; Bromine; Bromine - analysis; carbon; Cellulose; Cellulose - chemistry; Characterization and Evaluation of Materials; Chemical properties; Chemistry; Chemistry and Materials Science; Colorectal carcinoma; Combustion; Contamination; cooling; Decomposition; detection limit; effluents; Equipment Design; Feasibility; Feasibility Studies; Food; Food contamination; Food Science; Halogens; Honey; Honey - analysis; Hot Temperature; Identification and classification; Iodine; Iodine (Chemical element); Iodine - analysis; Laboratory Medicine; Limit of Detection; Mass spectrometry; Mass Spectrometry - methods; Methods; microwave treatment; Microwaves; Monitoring/Environmental Analysis; Observations; polyethylene film; Polyethylenes; Research Paper; Sample preparation; Scientific imaging; Thyroid gland; Trace analysis
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-015-8967-9

This work demonstrates the feasibility of ultra-trace determination of halogens in biological samples by inductively coupled plasma mass spectrometry (ICP-MS) after decomposition by microwave-induced combustion (MIC). The conventional MIC method was improved to allow the combustion of samples with mass higher than that used in previous works in order to achieve better limits of detection (LODs). The applicability of the proposed method for ultra-trace determination of bromine and iodine in organic samples was demonstrated here using honey. It was possible to decompose up to 1000 mg of honey using microcrystalline cellulose as a combustion aid and polyethylene film for sample wrapping. After combustion, analytes were absorbed using 50 mmol L⁻¹ NH₄OH and recoveries for Br and I were between 99 and 104 %, and relative standard deviations were lower than 5 %. Microwave-assisted alkaline dissolution (MA-AD) was also evaluated for honey sample preparation using NH₄OH or tetramethylammonium hydroxide solutions. However, the LODs for the MA-AD method were unsuitable because the high carbon content in digests required a dilution step prior to the analysis by ICP-MS. The LODs obtained by MIC were improved from 1143 to 34 ng g⁻¹ for Br and from 571 to 6.0 ng g⁻¹ for I, when compared to the MA-AD method. Furthermore, it was possible to decompose up to eight samples simultaneously in 30 min (including the cooling step) with very low reagent consumption and consequently lower generation of effluents, making MIC method well suited for routine ultra-trace determination of Br and I in honey.