FLOW-INJECTION AMPEROMETRIC DETERMINATION OF THIOCYANATE AND SELENOCYANATE AT A COBALT PHTHALOCYANINE MODIFIED CARBON-PASTE ELECTRODE
FLOW-INJECTION AMPEROMETRIC DETERMINATION OF THIOCYANATE AND SELENOCYANATE AT A COBALT PHTHALOCYANINE MODIFIED CARBON-PASTE ELECTRODE
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DOI：
10.1039/an9941901607
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发表时间：
1994-07-01
期刊：
影响因子：
4.2
通讯作者：
EFSTATHIOU, CE
中科院分区：
文献类型：
--
作者：
COOKEAS, EG;EFSTATHIOU, CE
含硫（SO32-、S2O3-和SCN-）、硒（SeO32-和SeCN-）、氮（NO2-）和砷（AsO2-）的无机阴离子在酞菁钴（CoPC-CPE）修饰的碳膏电极（CPE）上容易氧化。所有这些阴离子实际上都对CPE无电活性（除了SeCN-）。采用CoPC-CPE作为电流型流量传感器直接测定SCN-和SeCN-。在阳极检测电位和阴极再激活电位之间交替的电位的应用为两种阴离子提供了更稳定的检测器响应。SCN-和SeCN-分别使用+0.85至-0.30 V和+0.60至-0.30 V交变电位。SCN-的线性响应范围和检出限分别为250 μ mol l（-1）和0.8 μ mol l(-1) (pH值2.0)，SeCN-的线性响应范围和检出限分别为0.2 ~ 20 μ mol l（-1）和0.1 μ mol l(-1) （pH值7.0）。硫氰酸盐可以很容易地确定唾液样品后100倍稀释与配套电解质溶液。所得结果与标准分光光度法相当。
Inorganic anions containing sulfur (SO32-, S2O3-, and SCN-), selenium (SeO32- and SeCN-), nitrogen (NO2-), and arsenic (AsO2-) oxidize readily at a carbon paste electrode (CPE) modified with cobalt phthalocyanine (CoPC-CPE). All of these anions are virtually non electroactive (with the exception of SeCN-) towards the CPE. The CoPC-CPE was used as an amperometric flow sensor for the direct determination of SCN- and SeCN-. The application of a potential alternating between an anodic detection potential and a cathodic reactivation potential provided a more stable detector response for both anions. Potentials alternating in the ranges +0.85 to -0.30 V and +0.60 to -0.30 V were used for SCN- and SeCN-, respectively. The linear response ranges and the detection limits were 250 mu mol l(-1) and 0.8 mu mol l(-1) (at pH 2.0), respectively, for SCN-, and 0.2-20 mu mol l(-1) and 0.1 mu mol l(-1) (at pH 7.0), respectively, for SeCN-. Thiocyanate can be readily determined in saliva samples following 100-fold dilution with the supporting electrolyte solution. The results are comparable to those obtained using a standard spectrophotometric method.