Molína-Diaz A, Pascual-Reguera M I, Liñán-Veganzones E, Fernández de Córdova M L, Capitán-Vallvey L F
Department of Analytical Chemistry, Faculty of Experimental Sciences, University of Jaén, E-23071 Jaén, Spain.
Talanta. 1996 Feb;43(2):185-91. doi: 10.1016/0039-9140(95)01712-7.
Derivative spectrophotometry was applied to solid-phase spectrophotometry in order to enhance its sensitivity and remove the large background noise caused by the absorption of the resin layer itself, and avoid the necessity of preparing a blank. The determination of micro-amounts of molybdenum (at the ng ml(-1) level) with pyrocatechol violet to form a 11 blue complex in acid medium, which is fixed on a dextran-type anion-exchange resin (Sephadex QAE-A-25), is described as an example of the application of this technique. The absorbance of the resin, packed in a 1 mm spectrophotometric cell, was measured directly. The characteristic peak amplitude of the signal at 716 nm in the first-derivative spectra is useful for quantitative determination of molybdenum (2-8 ng ml(-1); RSD = 4, 30%) in natural and industrial water samples, plant tissues and soil extracts.
为了提高其灵敏度并消除由树脂层自身吸收引起的大量背景噪声，同时避免制备空白样的必要性，导数分光光度法被应用于固相分光光度法。以邻苯二酚紫在酸性介质中与钼形成1:1蓝色络合物为例，该络合物固定在葡聚糖型阴离子交换树脂（Sephadex QAE - A - 25）上，介绍了这种技术的应用。将树脂填充在1毫米分光光度池中，直接测量其吸光度。一阶导数光谱中716纳米处信号的特征峰幅度可用于定量测定天然水样、工业水样、植物组织和土壤提取物中的钼（2 - 8纳克/毫升；相对标准偏差 = 4, 30%）。
