Cyclic flow- injection chemiluminesent analysis of a small amount of chemical contamination using an on-line solid phase extraction for concentration

研究了循环流动注射法（循环FIA）重复测定铁（III）的方法。在过氧化氢存在下，用1,10-菲罗啉化学发光法测定了铁（III）。常规方法分析Fe（III）时，化学发光反应的最佳pH值为9.8。然而，循环化学发光法测定Fe（III）的最佳pH值为7，因为在pH为9.8时，作为背景信号的基线随着连续测定而增加。结果表明，化学发光法测定Fe（III）的灵敏度明显低于常规方法。为此，采用聚四氟乙烯毛细管在线固相萃取法研究了浓缩方法。单在线流动系统开发的循环FIA涉及另一条线，用于样品溶液中Fe（III）的浓度5分钟。在毛细管内富集铁（III）后，在载体线上用少量乙醇洗脱铁（III）。以铁（II）、1,10-菲罗啉、过氧化氢、泽非拉明（阳离子表面活性剂）和tris （pH缓冲剂）为载体溶液作为储层中的试剂废物。在温度控制下，Fe（III）在化学发光螺旋池中与载体溶液发生反应。以乙醇为洗脱液，100次重复测定Fe（III）的背景信号稳定。在最佳条件下，即浓度为pH8，浓缩时间为5 min，毛细管长度为5m，洗脱液体积为100μl，样品流速为2.8ml/min， Zephiramin为0.075M，过氧化氢为20%，Fe（III）的检出限为0.1ppb。在0.3 ~ 100ppb范围内，Fe（III）浓度与观察到的化学发光强度呈线性关系。自来水中痕量铁的测定结果与电感耦合等离子体原子发射光谱法测定结果吻合较好。少

A circulatory flow-injection method (cyclic FIA) for the repetitive determination of Fe(III) has been studied. The Fe(III) was determined by chemiluminescent measurement using 1,10-phenanthroline in the presence of hydrogen peroxide. The best pH for chemiluminescent reaction on the analysis of Fe(III) was proposed to be 9.8 by conventional method. However, the pH for cyclic chemiluminescent determination of Fe(III) was varied to 7 as a best pH, because that the base line as a background signal increased with a continuous determination at pH 9.8.As a result, the sensitivity of Fe(III) determination by the chemiluminescent method decreased remarkably compared to that of the conventional method. Therefor, the concentration method was investigated by on-line solid extraction using a Teflon capillary tube.The cyclic FIA developed by single on-line flow system involves another line for concentration of Fe(III) in sample solution for 5 min. After the concentration of Fe(III) inner the capilla … More ry cove, the Fe(III) was eluted on-line with a small amount of ethanol in the carrier line. The carrier solution as a reagent-waste in a reservoir was composed of Fe(II),1,10-phenanthroline, hydrogen peroxide, Zephiramine (caionic surfactant) and tris (pH buffer agent). The Fe(III) reacted to the carrier solution in the chemiluminescent spiral cell under the control of temperature. The background signal by 100 times repetition-determination for Fe(III) was stable using ethanol as a elute solution.The limit of the determination for Fe(III) was 0.1ppb under the optimum conditions, i.e., pH8 for concentration, 5 min as a concentration time, 5m as a concentration capillary tube length, 100μl for the volume as a elute solution, sample flow rate 2.8ml/min, 0.075M Zephiramin, and 20% hydrogen peroxide. A linear relationship between the concentration of Fe(III) and the observed chemiluminescent intensity was obtained over the range of 0.3〜100ppb. The results of a trace iron determination in tap water showed a good agreement with the values obtained by ICP-AES. Less