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Development of a microwave-assisted ultraviolet digestion method for biodiesel and subsequent trace elements determination by SF-ICP-MS
Journal of Analytical Atomic Spectrometry ( IF 3.1 ) Pub Date : 2018-05-14 00:00:00 , DOI: 10.1039/c8ja00095f
P. S. Barela 1, 2, 3, 4 , J. P. Souza 1, 2, 3, 4 , J. S. F. Pereira 1, 2, 3, 4 , J. C. Marques 2, 3, 4, 5 , E. I. Müller 4, 6, 7, 8 , D. P. Moraes 1, 2, 3, 4
Affiliation  

A microwave-assisted ultraviolet digestion (MW-UV) method for biodiesel is proposed for subsequent determination of Ba, Co, Cr, Cu, Mn, Ni, Pb, Sr, and V by sector field inductively coupled plasma mass spectrometry (SF-ICP-MS). It is the first time that the combination of microwave and ultraviolet radiation is proposed for biodiesel pretreatment achieving high efficiency of digestion even when dilute acid and high sample mass were used. Variable concentrations of nitric acid (2, 4.5, and 7 mol L−1), hydrogen peroxide (0, 1, and 2 mol L−1), and sample mass (ranging from 500 to 1000 mg) were evaluated to optimize digestion (i.e., low residual carbon content and low residual acidity). Using the proposed MW-UV method, residual carbon content (RCC) of 19.2% and residual acidity (RA) of 17.4% were obtained for digestion of 950 mg of biodiesel using 7 mol L−1 nitric acid. Samples were also digested by microwave-assisted digestion (MW-AD) using the same conditions and final digests were not suitable for analytes determination due to the high dissolved carbon content in solution (RCC about 27.4%). A study was performed in order to evaluate the maximum concentration of carbon that allowed accurate 52Cr, 60Ni, and 51V determinations without influence from polyatomic interferences by SF-ICP-MS. It was verified that interferences on 52Cr occurred when C concentration was higher than 150 mg L−1, requiring the use of medium resolution mode. The formation of polyatomic interference over 51V and 60Ni species in low resolution mode was not observed varying the C concentration. Analysis of a certified reference material (CRM, HU-1 used oil) by the proposed method agreed with certified values (t-test, 95% confidence level). Analyte recovery studies were in the range of 95–108%.

中文翻译:

微波辅助生物柴油紫外消解方法的建立及随后的SF-ICP-MS测定微量元素

提出了一种微波辅助生物柴油的紫外消解方法,用于随后的扇形场电感耦合等离子体质谱法测定钡,钴,铬,铜,锰,镍,铅,锶和钒。 -多发性硬化症)。首次提出将微波和紫外线结合用于生物柴油预处理,即使使用稀酸和高样品质量也能实现高消化效率。评估了可变浓度的硝酸(2、4.5和7 mol L -1),过氧化氢(0、1、2 mol L -1)和样品质量(500至1000 mg)以优化消化(IE,低残留碳含量和低残留酸度)。使用拟议的MW-UV方法,使用7 mol L -1硝酸消化950 mg生物柴油时,残留碳含量(RCC)为19.2%,残留酸度(RA)为17.4%。样品也通过微波辅助消解(MW-AD)在相同条件下进行消解,由于溶液中的溶解碳含量较高(RCC约为27.4%),最终消解物不适合分析物的测定。为了评估最大碳浓度,可以进行准确的52 Cr,60 Ni和51 V测定,而不受SF-ICP-MS的多原子干扰的影响,进行了一项研究。经验证,对52的干扰当C浓度高于150 mg L -1时发生Cr ,需要使用中分辨率模式。在低分辨率模式下,未观察到在51 V和60 Ni物种上形成多原子干扰,这会改变C的浓度。通过建议的方法对认证的参考物质(CRM,HU-1废油)进行分析,与认证值(t检验,置信度为95%)相符。分析物回收率研究在95%至108%之间。
更新日期:2018-05-14
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