Evmiridis N P, Thanasoulias N K, Vlessidis A G
University of Ioannina, Department of Chemistry, Laboratory of Analytical Chemistry, 45110 Ioannina, Greece.
Talanta. 1998 May;46(1):179-96. doi: 10.1016/s0039-9140(97)00272-5.
An investigation of chemiluminescence (CL)-emission generated by the oxidation of pyrogallol using various inorganic oxidant compounds is reported in this F.I.A.-merging zone application. The oxidant compounds that showed measurable CL-emission were permanganate, periodate, hypochlorite anions, cerium(IV) and hydrogen peroxide. The different oxidant compounds showed CL-emissions at different pH-ranges. The CL-emission was limited by the inner filter effect and this was more intense for oxidants of selective oxidation. Kinetic effects were also found in the case of oxidation by permanganate. Plots of CL-emission against pH give evidence of speciation and or deactivation mechanism effects. The analytical parameters for the determination of the oxidants are given. Sensitivities of 895 600, 19 500, 33 723, 10 680 and 56 703 mV M(-1) were found for the determination of permanganate, cerium(IV), periodate, hypochlorite and hydrogen peroxide, respectively. The calibration curves of the oxidant determination were generally S-shaped; the S-shaped calibration curve of periodate was closer to a straight line relationship while that of hypochlorite was almost a straight line; detection limits in the range of 10(-4) M oxidant concentration were found for nearly all oxidants. The analytical parameters for determination of pyrogallol by the CL-emission generated through oxidation by the different oxidants at optimum conditions were 1.16x10(6) mV M(-1) for permanganate; 0.086x10(6) mV M(-1) for cerium(IV); 0.91x10(6) mV M(-1) for periodate; 0.012x10(6) mV M(-1) for hypochlorite; and 0.25x10(6) mV M(-1) for hydrogen peroxide. The detection limit was 1.0x10(-4) M. The nearly straight-line relationship (initial part of the plot) for CL-emission with oxidant concentration gives an indication that the CL-reaction of pyrogallol oxidation by hypochlorite proceeds through a process that involves energy transfer while the pronounced S-shaped curve produced by permanganate gives the indication that the reaction proceeds through a process that does not involve energy transfer according to the mathematical model of CL-emission that controls the F.I.A.-merging zone technique of the flow apparatus used in this work. The sequence of completeness of the oxidation process by each oxidant was MnO(4)(-)>H(2)O(2)>IO(4)(-)>OCl(-); the stoichiometric quantity of the oxidant per pyrogallol molecule for the rapid part of the overall oxidation by each different oxidant was attempted; this is an index-value of the oxidation state of the fluorescent excited molecule. Finally, the impact of the above findings for further analytical applications is discussed.
本文在流动注射-合并区应用中报道了使用各种无机氧化剂化合物氧化邻苯三酚产生化学发光（CL）发射的研究。显示出可测量CL发射的氧化剂化合物有高锰酸盐、高碘酸盐、次氯酸盐阴离子、铈（IV）和过氧化氢。不同的氧化剂化合物在不同的pH范围内显示出CL发射。CL发射受内滤效应限制，对于选择性氧化的氧化剂，这种效应更强。在高锰酸盐氧化的情况下也发现了动力学效应。CL发射对pH的曲线证明了物种形成和/或失活机制效应。给出了测定氧化剂的分析参数。测定高锰酸盐、铈（IV）、高碘酸盐、次氯酸盐和过氧化氢的灵敏度分别为895600、19500、33723、10680和56703 mV M⁻¹。氧化剂测定的校准曲线通常为S形；高碘酸盐的S形校准曲线更接近直线关系，而次氯酸盐的校准曲线几乎是一条直线；几乎所有氧化剂在氧化剂浓度为10⁻⁴ M范围内的检测限都被发现。在最佳条件下，通过不同氧化剂氧化产生的CL发射测定邻苯三酚的分析参数为：高锰酸盐为1.16×10⁶ mV M⁻¹；铈（IV）为0.086×10⁶ mV M⁻¹；高碘酸盐为0.91×10⁶ mV M⁻¹；次氯酸盐为0.012×10⁶ mV M⁻¹；过氧化氢为0.25×10⁶ mV M⁻¹。检测限为1.0×10⁻⁴ M。CL发射与氧化剂浓度的几乎直线关系（曲线的初始部分）表明，次氯酸盐氧化邻苯三酚的CL反应通过涉及能量转移的过程进行，而高锰酸盐产生的明显S形曲线表明，根据控制本工作中使用的流动装置的流动注射-合并区技术的CL发射数学模型，该反应通过不涉及能量转移的过程进行。每种氧化剂氧化过程的完整顺序为MnO₄⁻＞H₂O₂＞IO₄⁻＞OCl⁻；尝试确定每种不同氧化剂在总体氧化快速部分中每个邻苯三酚分子的氧化剂化学计量数量；这是荧光激发分子氧化态的一个指标值。最后，讨论了上述发现对进一步分析应用的影响。
