Universidade Federal da Bahia, Instituto de Química, Departamento de Química Analítica, Campus Universitário de Ondina, 40170-115, Salvador, Bahia, Brazil.
Universidade Estadual do Sudoeste da Bahia, Laboratório de Química Analítica, Rua José Moreira Sobrinho S/n, Jequiezinho, 45206-190, Jequié, Bahia, Brazil.
Talanta. 2021 Jan 15;222:121514. doi: 10.1016/j.talanta.2020.121514. Epub 2020 Aug 7.
A method was developed based on reversed-phase vortex-assisted liquid-liquid microextraction (RP-VALLME) combined with energy dispersive X-ray fluorescence (EDXRF) spectrometry for the determination of Cu, Mn, Ni, and Pb in diesel oil samples. In this procedure, a nitric acid solution was used as the extraction phase to isolate analytes from organic samples. After a centrifugation step, the aqueous phase was added dropwise to a filter paper disc for EDXRF determinations. The following variables were optimized: type of extraction phase solution, concentration of the extraction phase, stirring time, and sample volume. Some instrumental parameters were also evaluated: atmospheric condition, irradiation energy, and irradiation time. Using 100 μL of a 0.075 mol L nitric acid solution as the extraction phase for a sample volume of 5.0 mL and a stirring time of 45 s, the limits of detection were 14, 8, 10, and 7 μg L for Cu, Mn, Ni, and Pb, respectively. The enrichment factors obtained were 34 (Cu), 62 (Mn), 59 (Ni), and 64 (Pb). The precisions, expressed as relative standard deviations (RSDs, %), were calculated from ten replications of the experiment under optimized conditions using standard solutions containing 200 μg L and 400 μg L of all four analytes and ranged between 2.1 and 6.4%. The results of recovery tests ranged from 87 to 112%. The proposed procedure was efficiently applied to the determination of the four analytes in diesel oil samples. The results were compared with those obtained by inductively coupled plasma optical emission spectrometry (ICP-OES) after sample digestion, and no significant differences were found.
建立了一种基于反相涡旋辅助液-液微萃取（RP-VALLME）与能量色散 X 射线荧光光谱法（EDXRF）联用测定柴油样品中 Cu、Mn、Ni 和 Pb 的方法。在该方法中，采用硝酸溶液作为萃取相从有机样品中分离分析物。离心后，将水相逐滴加入滤纸圆片，用于 EDXRF 测定。优化了以下变量：萃取相溶液的类型、萃取相的浓度、搅拌时间和样品体积。还评估了一些仪器参数：大气条件、辐照能量和辐照时间。采用 100 μL 0.075 mol·L-1 硝酸溶液作为萃取相，样品体积为 5.0 mL，搅拌时间为 45 s，Cu、Mn、Ni 和 Pb 的检出限分别为 14、8、10 和 7 μg·L-1。获得的富集因子分别为 34（Cu）、62（Mn）、59（Ni）和 64（Pb）。在优化条件下，用含 200 μg·L 和 400 μg·L 四种分析物的标准溶液重复实验十次，计算得到的精密度（表示为相对标准偏差，%）在 2.1%至 6.4%之间。回收试验的结果在 87%至 112%之间。该方法可有效地用于测定柴油样品中这四种分析物的含量。与样品消化后用电感耦合等离子体发射光谱法（ICP-OES）得到的结果进行了比较，没有发现显著差异。
