Costa Vanize C, Picoloto Rochele S, Hartwig Carla A, Mello Paola A, Flores Erico M M, Mesko Marcia F
Centro de Ciências Químicas, Farmacêuticas e de Alimentos, Universidade Federal de Pelotas, 96010-610, Pelotas, RS, Brazil.
Departamento de Química, Universidade Federal de Santa Maria, 97105-900, Santa Maria, RS, Brazil.
Anal Bioanal Chem. 2015 Oct;407(26):7957-64. doi: 10.1007/s00216-015-8967-9. Epub 2015 Aug 27.
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. Graphical Abstract A high mass of honey was efficiently digested by MIC for subsequent Br and I determination by ICP-MS.
本研究证明了采用微波诱导燃烧（MIC）分解后，通过电感耦合等离子体质谱法（ICP-MS）对生物样品中的卤素进行超痕量测定的可行性。对传统的MIC方法进行了改进，以使质量高于以往工作中使用的样品能够燃烧，从而实现更好的检测限（LOD）。本文使用蜂蜜证明了所提出的方法在有机样品中超痕量测定溴和碘的适用性。使用微晶纤维素作为助燃剂和聚乙烯薄膜包裹样品，最多可分解1000 mg蜂蜜。燃烧后，用50 mmol L⁻¹ NH₄OH吸收分析物，Br和I的回收率在99%至104%之间，相对标准偏差低于5%。还评估了使用NH₄OH或四甲基氢氧化铵溶液通过微波辅助碱溶法（MA-AD）制备蜂蜜样品。然而，MA-AD方法的检测限不合适，因为消化液中的高碳含量需要在ICP-MS分析之前进行稀释步骤。与MA-AD方法相比，通过MIC获得的检测限对于Br从1143 ng g⁻¹提高到34 ng g⁻¹，对于I从571 ng g⁻¹提高到6.0 ng g⁻¹。此外，在30分钟内（包括冷却步骤）可以同时分解多达八个样品，试剂消耗非常低，因此产生的废水也较少，这使得MIC方法非常适合蜂蜜中Br和I的常规超痕量测定。图形摘要通过MIC有效地消化大量蜂蜜，以便随后通过ICP-MS测定Br和I。
