Faculty of Pharmaceutical Sciences, Gabriel Monteiro da Silva Street, 714, 37130-000, Federal University of Alfenas - UNIFAL-MG, Alfenas, MG, Brazil.
Talanta. 2011 Oct 15;85(5):2707-10. doi: 10.1016/j.talanta.2011.08.003. Epub 2011 Aug 10.
This paper describes a study about the influence of microwave radiation using closed vessels on fluoride, chloride, nitrate and sulfate concentrations in aqueous media. The experiments were processed by heating water using PFA vessels and a microwave cavity oven, determining the anions by ion chromatography. The influence of the exposure time, the atmospheric composition, the kind of heating (water bath or microwave radiation) and the possible formation of hydrogen peroxide were investigated. The limits of quantification for fluoride, chloride, nitrate and sulfate were respectively of 0.17, 0.15, 0.55 and 0.57 μg L(-1), and precision, expressed as RSD, was <4% for all considered anions. The hydrogen peroxide was quantified by spectrophotometry, and the limit of quantification and precision were 24 μg L(-1) and <5% (n=10), respectively. The results demonstrate a significant increase in the anion concentration levels (between 63 and 89%) when microwave heating was used in comparison with heating by water bath. In addition, these changes observed can be mainly attributed to the species transfers, either between gaseous (atmospheric gases) and liquid (water) phases for nitrate, or between vessels walls and water for fluoride, chloride and sulfate. Additionally, hydrogen peroxide concentration higher than 45 μg L(-1) was determined when water was exposed to microwave radiation.
本文描述了一项关于在密闭容器中使用微波辐射对水相介质中氟化物、氯、硝酸盐和硫酸盐浓度影响的研究。实验通过使用 PFA 容器和微波腔式烤箱加热水，通过离子色谱法测定阴离子。考察了暴露时间、大气组成、加热方式（水浴或微波辐射）以及可能形成的过氧化氢对实验的影响。氟化物、氯、硝酸盐和硫酸盐的定量限分别为 0.17、0.15、0.55 和 0.57 μg L(-1)，所有考虑的阴离子的精密度（表示为 RSD）均<4%。通过分光光度法定量测定过氧化氢，其定量限和精密度分别为 24 μg L(-1)和<5%（n=10）。结果表明，与水浴加热相比，微波加热时阴离子浓度水平显著增加（63%至 89%之间）。此外，这些观察到的变化主要归因于硝酸盐在气相（大气气体）和液相（水）之间，或氟化物、氯和硫酸盐在容器壁和水之间的物质转移。此外，当水暴露于微波辐射时，过氧化氢浓度会高于 45μg L(-1)。
