Sharma Nisha, Pillai Aradhana K K V, Pathak Neeraj, Jain Archana, Verma Krishna K
Department of Chemistry, Rani Durgavati University, Jabalpur 482001, Madhya Pradesh, India.
Anal Chim Acta. 2009 Aug 26;648(2):183-93. doi: 10.1016/j.aca.2009.07.006. Epub 2009 Jul 7.
Liquid-phase microextraction (LPME) has been investigated for trace analysis in the present work in conjunction with fibre-optic-based micro-spectrophotometry which accommodates sample volume of 1 microL placed between the two ends of optical fibres. Methods have been evolved for the determination of (i) 1-100 microM and 0.5-20 microM of thiols by single drop microextraction (SDME) and LPME in 25 microL of the organic solvent, respectively, involving their reaction with the Ellman reagent and ion pair microextraction of thiolate ion formed; (ii) 70 microg to 7 mg L(-1) of chlorine/chlorine dioxide by headspace in-drop reaction with alternative reagents, viz., mixed phenylhydrazine-4-sulphonic acid and N-(1-naphthyl)ethylenediamine dihydrochloride, o-dianisidine, o-tolidine, and N,N-diethyl-p-phenylenediamine; (iii) 0.2-4 mg L(-1) of ammonia by reaction with 2,4-dinitro-1-fluorobenzene to give 2,4-dinitroaniline which was diazotized and coupled with 1-naphthylamine, the resulting dye was subjected to preconcentration by solid-phase extraction and LPME; and (iv) 25-750 microg L(-1) of iodide/total iodine by oxidation of iodide by 2-iodosobenzoate, microextraction of iodine in organic solvent, and re-extraction into aqueous starch-iodide reagent drop held in the organic phase. LPME using 25-30 microL of organic solvent was found to produce more sensitive results than SDME. The cuvetteless spectrophotometry as used in combination with sample handling techniques produced limits of detection of analytes which were better than obtained by previously reported spectrophotometry.
在本研究中，结合基于光纤的微量分光光度法对液相微萃取（LPME）进行了痕量分析研究，该方法可容纳置于光纤两端之间1微升的样品体积。已开发出以下测定方法：（i）分别通过单滴微萃取（SDME）和LPME在25微升有机溶剂中测定1 - 100微摩尔/升和0.5 - 20微摩尔/升的硫醇，涉及它们与埃尔曼试剂的反应以及对形成的硫醇盐离子进行离子对微萃取；（ii）通过顶空液滴内反应，使用替代试剂，即混合苯肼 - 4 - 磺酸和N - （1 - 萘基）乙二胺二盐酸盐、邻联茴香胺、邻联甲苯胺和N，N - 二乙基对苯二胺，测定70微克/升至7毫克/升的氯/二氧化氯；（iii）通过与2,4 - 二硝基 - 1 - 氟苯反应生成2,4 - 二硝基苯胺，将其重氮化并与1 - 萘胺偶联，对所得染料通过固相萃取和LPME进行预浓缩，从而测定0.2 - 4毫克/升的氨；（iv）通过2 - 碘代苯甲酸氧化碘化物，在有机溶剂中对碘进行微萃取，并将其再萃取到保持在有机相中的水性淀粉 - 碘化物试剂滴中，测定25 - 750微克/升的碘化物/总碘。发现使用25 - 30微升有机溶剂的LPME比SDME产生更灵敏的结果。与样品处理技术结合使用的无比色皿分光光度法所产生的分析物检测限优于先前报道的分光光度法。
