Laboratory of Instrumentation and Analytical Chemistry, Dalian Institute of Chemical Physics, CAS, Dalian, Liaoning 116023, P. R. China.
Analyst. 2011 Dec 7;136(23):5025-9. doi: 10.1039/c1an15679a. Epub 2011 Oct 12.
A ratiometric indicator-displacement assay (RIDA) array has been developed for the semi-quantitative colorimetric determination of chloride, bromide, and iodide anions. Determinations of these halide anions follow the displacement reaction using the chelate compound of (2-(3,5-dibromo-2-pyridylazo)-5-(diethylamino)phenol) (3,5-Br2-PADAP) and heavy metal salts as colorimetric reagent. Different from regular silver nitrate titrations, the chloride, bromide, and iodide anions compete with the 3,5-Br2-PADAP ligand and change the colour of the 3,5-Br2-PADAP-metal chelate compound dramatically. These clearer colour changes make the semi-quantitative colorimetric determination of chloride, bromide, and iodide anions possible. The colour changes are imaged using a conventional flatbed scanner, and digitized. After statistical analysis, these colour changes in the RIDA array provide facile identification of chloride, bromide, and iodide anions at a wide concentration range (10 μM to 10 mM) without any misclassification. The RIDA array is able to discriminate without misclassifications among seven concentrations of chloride, bromide, and iodide anions. No shelf life issue exists because the chelating compounds react with halide anions directly without any pre-immobilizations.
已开发出比率型指示剂置换分析（RIDA）阵列，用于半定量比色测定氯离子、溴离子和碘离子。这些卤化物阴离子的测定遵循使用（2-（3,5-二溴-2-吡啶偶氮）-5-（二乙氨基）苯酚）（3,5-Br2-PADAP）和重金属盐作为显色试剂的螯合物的置换反应。与常规的硝酸银滴定法不同，氯离子、溴离子和碘离子与 3,5-Br2-PADAP 配体竞争，并显著改变 3,5-Br2-PADAP-金属螯合物的颜色。这些更明显的颜色变化使得半定量比色测定氯离子、溴离子和碘离子成为可能。使用常规平板扫描仪对颜色变化进行成像，并进行数字化。经过统计分析，RIDA 阵列中的这些颜色变化可在宽浓度范围内（10 μM 至 10 mM）轻松识别氯离子、溴离子和碘离子，而不会出现任何分类错误。RIDA 阵列能够在不出现分类错误的情况下区分七种浓度的氯离子、溴离子和碘离子。由于螯合化合物直接与卤化物阴离子反应，而无需任何预固定，因此不存在保质期问题。
