An automated system to perform liquid-liquid extraction in monosegmented flow analysis is described. The system is controlled by a microcomputer that can track the localization of the aqueous monosegmented sample in the manifold. Optical switches are employed to sense the gas-liquid interface of the air bubbles that define the monosegment. The logical level changes, generated by the switches, are flagged by the computer through a home-made interface that also contains the analogue-to-digital converter for signal acquisition. The sequence of operations, necessary for a single extraction or for concentration of the analyte in the organic phase, is triggered by these logical transitions. The system was evaluated for extraction of Cd(II), Cu(II) and Zn(II) and concentration of Cd(II) from aqueous solutions at pH 9.9 (NH3/NH4Cl buffer) into chloroform containing PAN (1-(2-pyridylazo)-2-naphthol) . The results show a mean repeatability of 3% (rsd) for a 2.0 mg l-1 Cd(II) solution and a linear increase of the concentration factor for a 0.5mg l-1 Cd(II) solution observed for up to nine extraction cycles.
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机译:描述了一种在单段流量分析中执行液-液萃取的自动化系统。该系统由一台微型计算机控制,该计算机可以跟踪歧管中含水的单段样品的定位。使用光学开关来感测限定单段的气泡的气-液界面。开关产生的逻辑电平变化由计算机通过一个自制的接口进行标记,该接口还包含用于信号采集的模数转换器。这些逻辑转换可触发单次萃取或有机相中分析物浓缩所需的操作顺序。评估了系统在pH 9.9(NH3 / NH4Cl缓冲液)中从含PAN(1-(2-吡啶基偶氮-2-萘酚)。结果表明,对于2.0 mg l -1 sup> Cd(II)溶液,平均重复性为3%(rsd),而对于0.5mg l -1 <观察到多达9个萃取循环的Cd(II)溶液。
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