Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University, Thessaloniki 54124, Greece.
Anal Chim Acta. 2013 Apr 10;771:50-5. doi: 10.1016/j.aca.2013.02.003. Epub 2013 Feb 16.
A novel automatic on-line liquid phase micro-extraction method based on drop-in-plug sequential injection lab-at-valve (LAV) platform was proposed for metal preconcentration and determination. A flow-through micro-extraction chamber mounted at the selection valve was adopted without the need of sophisticated lab-on-valve components. Coupled to flame atomic absorption spectrometry (FAAS), the potential of this lab-at-valve scheme is demonstrated for trace lead determination in environmental and biological water samples. A hydrophobic complex of lead with ammonium pyrrolidine dithiocarbamate (APDC) was formed on-line and subsequently extracted into an 80 μL plug of chloroform. The extraction procedure was performed by forming micro-droplets of aqueous phase into the plug of the extractant. All critical parameters that affect the efficiency of the system were studied and optimized. The proposed method offered good performance characteristics and high preconcentration ratios. For 10 mL sample consumption an enhancement factor of 125 was obtained. The detection limit was 1.8 μg L(-1) and the precision expressed as relative standard deviation (RSD) at 50.0 μg L(-1) of lead was 2.9%. The proposed method was evaluated by analyzing certified reference materials and applied for lead determination in natural waters and urine samples.
一种基于插入式顺序注射阀上实验室（LAV）平台的新型自动在线液相微萃取方法，用于金属预浓缩和测定。采用流通式微萃取室，无需复杂的阀上实验室组件，安装在选择阀上。结合火焰原子吸收光谱法（FAAS），该阀上方案的潜力已在环境和生物水样中痕量铅的测定中得到证明。在线形成铅与氨丙基二硫代氨基甲酸盐（APDC）的疏水络合物，随后用 80μL 氯仿萃取。通过将水相微滴形成到萃取剂的塞子中来进行萃取程序。研究并优化了所有影响系统效率的关键参数。该方法提供了良好的性能特征和高浓缩比。对于 10 mL 的样品消耗，获得了 125 的增强因子。检测限为 1.8μg/L，在 50.0μg/L 的铅浓度下，相对标准偏差（RSD）为 2.9%。通过分析认证参考材料对所提出的方法进行了评估，并将其应用于天然水和尿液样品中铅的测定。
