In the present study, a new cloud point extraction methodology based on the selective preconcentration and the extraction of stable lead in acidic conditions with 4′,4''(5'')-di-tert-butyldicyclohexano-18-crown-6 as a chelating agent was developed, optimized and validated. A mixture of Triton X-114 as non-ionic surfactant and CTAB as cationic surfactant was used to produce micellar structures that incorporate the chelating agent. Phase separation, induced by coacervation, was achieved by increasing the temperature of the system above the cloud point temperature. Pb extraction efficiency was maximized through an optimisation process where the effect of each parameter (i.e. non-ionic and ionic surfactant concentrations, pH, chelating agent concentration and cloud point temperature) on the chemical recoveries of Pb was assessed. Under optimum experimental conditions, the method reaches recoveries greater than 67% for Pb in a variety of complex matrices. In order to facilitate the quantification of Pb by plasma based instrumentations, a back-extraction procedure using aqueous solution of ammonium citrate were performed on the surfactant rich phase in order to reduce the effects on sample introduction and non-spectral interferences. LOD and LOQ of 0.8 µg L⁻¹ and 2.6 µg L⁻¹, respectively, were determined by ICP-OES for the complete procedure. Using the back-extraction approach, a preconcentration factor of 39 was achieved for an initial sample volume of 195 mL. The ruggedness of the methodology was validated by determining Pb concentration in various environmental and biological samples.

在本研究中，一种基于选择性预浓缩和酸性条件下稳定铅的提取的新浊点提取方法，该方法以4'，4''（5''）-二叔丁基二环己基-18-冠-6作为酸性条件开发，优化和验证了一种螯合剂。Triton X-114作为非离子表面活性剂和CTAB作为阳离子表面活性剂的混合物用于生产掺入螯合剂的胶束结构。通过凝聚引起的相分离是通过将系统温度升高到浊点温度以上来实现的。通过优化过程最大程度地提高了铅的提取效率，其中评估了各个参数（即非离子和离子表面活性剂浓度，pH，螯合剂浓度和浊点温度）对铅化学回收率的影响。在最佳实验条件下，该方法在多种复杂基质中对铅的回收率均超过67％。为了促进基于等离子体的仪器对Pb的定量分析，对富含表面活性剂的相使用柠檬酸铵水溶液进行了反萃取程序，以减少对样品引入和非光谱干扰的影响。LOD和LOQ为0.8 µg L对于整个过程，用ICP-OES分别测定^-1和2.6 µg L ^-1。使用反萃取方法，初始样品体积为195 mL，预浓缩系数为39。通过确定各种环境和生物样品中的Pb浓度，可以验证该方法的坚固性。