Alizadeh Nina, Mahjoub Mohammad
Department of Chemistry, University of Guilan, P.B. 41335-1914, Rasht, Iran,
Environ Monit Assess. 2015 May;187(5):248. doi: 10.1007/s10661-015-4478-6. Epub 2015 Apr 14.
A new sensitive kinetic spectrophotometric method described for the determination of trace amounts of sulfides based on the addition reaction of sulfide ions with malachite green has been investigated in aqueous and micellar media at 25 °C. The variables affecting the rate of the reaction were investigated, and the optimum conditions were established. Under the optimum experimental conditions, decreases in the absorbance of malachite green at 615 nm in the absence and 630 nm in the presence of micelle particles, their λ max, were proportional to the concentrations of sulfide ions at the first 15 and 25 s from initiation of the reaction. The working curve was linear over the concentration range 50-1200 ng mL(-1) of sulfide ions with a fixed time method at the first 15 and 25 s from initiation of the reaction in aqueous medium and 25-1750 ng mL(-1) with a fixed time method at the first 15 s and 25-1500 ng mL(-1) for primitive 25 s in micellar medium. For the proposed kinetic method, the experimental and theoretical limit of detection (LOD) and limit of quantification (LOQ) in the presence and absence of micelle particles were obtained and tabulated at Δt = 15 and 25 s. The effective range concentration was achieved from the plot of Ringbom in both media and reported. Different surfactants, such as nonionic surfactant (Triton-X100), anionic surfactant sodium dodecyl sulfate (SDS), and cationic surfactant cetyltrimethylammonium bromide (CTAB) and cetylpyridinium chloride (CPC), were investigated and Triton X-100 selected as a suitable surfactant. To valuable vision into the reaction pathways, pseudo-first-order condition was applied and different kinetic parameters like ΔG (≠), ΔE (≠), ΔS (≠), and ΔH (≠) computed. The 2:1 stoichiometry of malachite green to sulfide ions was indicated by the results of mole ratio and Job's method of continuous variation. The effect of different environments on the interfering of various ions on sulfide determination with the suggested method was studied, and final results have been presented. To investigate the usefulness of the different media of the proposed method, sulfide ions were determined in natural waters such as river and spring samples without any purification or using masking reagents.
本文描述了一种基于硫化物离子与孔雀石绿的加成反应测定痕量硫化物的新型灵敏动力学分光光度法，该方法在25℃的水相和胶束介质中进行了研究。考察了影响反应速率的变量，并确定了最佳条件。在最佳实验条件下，在反应开始后的前15秒和25秒内，水相中615nm处以及胶束存在时630nm处孔雀石绿吸光度的降低，即其λmax，与硫化物离子浓度成正比。在水相中，采用固定时间法，反应开始后的前15秒和25秒内，硫化物离子浓度在50 - 1200 ng mL⁻¹范围内工作曲线呈线性；在胶束介质中，反应开始后的前15秒，硫化物离子浓度在25 - 1750 ng mL⁻¹范围内工作曲线呈线性，反应开始后的前25秒，硫化物离子浓度在25 - 1500 ng mL⁻¹范围内工作曲线呈线性。对于所提出的动力学方法，在存在和不存在胶束颗粒的情况下，在Δt = 15秒和25秒时获得并列出了实验和理论检测限（LOD）和定量限（LOQ）。通过两种介质中的林邦曲线得到有效浓度范围并进行了报道。研究了不同表面活性剂，如非离子表面活性剂（Triton-X100）、阴离子表面活性剂十二烷基硫酸钠（SDS）以及阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）和十六烷基吡啶氯化物（CPC），并选择Triton X-100作为合适的表面活性剂。为深入了解反应途径，应用了准一级条件并计算了不同的动力学参数，如ΔG(≠)、ΔE(≠)、ΔS(≠)和ΔH(≠)。通过摩尔比和连续变化的Job方法的结果表明孔雀石绿与硫化物离子的化学计量比为2:1。研究了不同环境对所提方法中各种离子干扰硫化物测定的影响，并给出了最终结果。为考察所提方法不同介质的实用性，在未进行任何纯化或使用掩蔽剂的情况下，对河水和泉水等天然水样中的硫化物离子进行了测定。
