Departamento de Química Analítica, Universidade Federal Fluminense, Outeiro de São João Batista s/n, Centro, Niterói, RJ 24020-141, Brazil.
Departamento de Química Analítica, Universidade Federal Fluminense, Outeiro de São João Batista s/n, Centro, Niterói, RJ 24020-141, Brazil.
Talanta. 2015 Jan;132:733-8. doi: 10.1016/j.talanta.2014.10.019. Epub 2014 Oct 23.
This work reports the development of a novel extraction method for total Hg determination in oil samples. After extracting Hg from samples it was quantified in the extracts by cold vapor atomic absorption spectrometry (CV-AAS), employing a laboratory-made gas-liquid separator (GLS) and NaBH4 as reducing agent. The extraction of Hg from samples was carried out by extraction induced by emulsion breaking (EIEB), which is based on the formation and breaking of water-in-oil emulsion between the oil samples and an extractant solution containing an emulsifying agent (surfactant) and nitric acid. Operational parameters of the GLS were evaluated in order to set the best performance of the measurement system. In these studies it was proven that the volume of sample and the concentration of HCl added to the sample extracts had significant influence on Hg response. The best conditions were achieved by adding 0.5 mL of a 0.3 mol L(-1) HCl solution on 1 mL of sample extract. The extraction conditions were also optimized. The highest efficiency was observed when 4 mL of a solution containing 2.5% triton X-100 and 15% v/v HNO3 were employed for the extraction of Hg contained in 20 mL of sample. Emulsion breaking was performed by heating at 80 °C and took approximately 20 min. The limit of quantification of the method was 1.9 µg L(-1) and recovery percentages between 80% and 103% were observed when spiked samples (2 and 10 µg L(-1)) of diesel oil, biodiesel and mineral oil were analyzed.
本工作报道了一种用于测定油样中总汞的新型萃取方法的开发。从样品中萃取汞后，采用实验室自制的气液分离器（GLS）和硼氢化钠作为还原剂，在萃取物中用冷蒸气原子吸收光谱法（CV-AAS）定量。Hg 的萃取是通过破乳诱导萃取（EIEB）进行的，该方法基于油样与含有乳化剂（表面活性剂）和硝酸的萃取剂溶液之间形成和破乳的水包油乳液。评估了 GLS 的操作参数，以确定测量系统的最佳性能。在这些研究中，证明了样品体积和添加到样品提取物中的 HCl 浓度对 Hg 响应有显著影响。通过在 1 mL 样品提取物中添加 0.5 mL 0.3 mol L(-1) HCl 溶液，可以获得最佳条件。还优化了萃取条件。当 4 mL 含有 2.5% Triton X-100 和 15% v/v HNO3 的溶液用于萃取 20 mL 样品中的 Hg 时，效率最高。通过在 80°C 下加热进行破乳，大约需要 20 分钟。当分析柴油、生物柴油和矿物油的加标样品（2 和 10 µg L(-1)）时，该方法的检出限为 1.9 µg L(-1)，回收率在 80%至 103%之间。
