Abstract

A computer-controlled multicommuted flow-batch system is reported that allows for the online cloud point extraction of metal ions followed by high-resolution continuum source flame atomic absorption spectrometric (HR-CS GFAAS) detection. This approach combines reduced sample and reagent consumption and a short analysis time with the increased precision and sensitivity characteristic of flow-batch analysis and modern extraction techniques. As proof of concept, cadmium in aqueous solutions was determined by the formation of a hydrophobic complex [Cd(PAN)₂]. Parameters related to complex formation (pH, pyridyl-azo-naphthol-PAN concentration, complexation time), cloud point extraction (Triton X-114 concentration, electrolyte composition, rich phase trapping), and the multicommuted flow-batch system (flow rates, timing control) were optimized. A small column packed with hydrophobic cotton was used as the interface between the extraction and detection stages to stack the cadmium-containing rich phase in a short plug. Optimized parameters led to a 5.0 to 75.0 µg L⁻¹ linear range, 1.3 µg L⁻¹ limit of detection, 4.3 µg L⁻¹ limit of quantification and 1.8% coefficient of variation (n = 12). Accuracy was evaluated by analyzing a certified reference material EP-H (drinking water) and by recovery tests employing tap water, groundwater, mineral water, and reuse water samples.

摘要

据报道，一种计算机控制的多通流批处理系统允许在线提取金属离​​子浊点，然后进行高分辨率连续源火焰原子吸收光谱 (HR-CS GFAAS) 检测。这种方法结合了减少样品和试剂消耗、缩短分析时间以及提高流批分析和现代提取技术的精度和灵敏度特性。作为概念验证，水溶液中的镉是通过形成疏水复合物 [Cd(PAN) ₂]。与络合物形成（pH、吡啶基-偶氮-萘酚-PAN 浓度、络合时间）、浊点萃取（Triton X-114 浓度、电解质组成、富相捕集）和多通流分批系统（流速、时序控制）进行了优化。填充有疏水棉的小柱用作萃取和检测阶段之间的界面，以将富含镉的相堆叠在短塞中。优化参数导致 5.0 至 75.0 µg L ^-1线性范围，1.3 µg L ^-1检测限，4.3 µg L ^-1量化限制和 1.8% 的变异系数（n = 12）。通过分析经认证的参考材料 EP-H（饮用水）和使用自来水、地下水、矿泉水和再利用水样品的回收率测试来评估准确性。