Abstract
AbstractAs soon as scientists became aware of the fact that the bio-availability, toxicity and mobility of an element strongly depend on the concentration of elements, the study on quantification of different elements are receiving more and more attention. Environmental or bio-inorganic chemistry has been established the discipline which interfaces the research areas of inorganic trace analysis and biology and environment. Owing to trace analytes and high matrix content are always the main obstacles should be overcome in conjuncting analytical chemistry with biological and environmental science, the development an in-situ, continuous and robust analytical technique dealing with high salt contented samples is still highly demanded.To monitor the temporal variation of trace elements in the living animal, microdialysis sampling technique has become an indispensible tool. Owing to the salt content in the pufusate, ringer solution, is near 1% w/v and the concentration of trace elements might be as low as mg L-1- sub-mg L-1, direct determination of trace elements in such samples is considered to be impossible for current instrumentation techniques. In order to get rid of the salt interferences prior to the instrumental analysis, a novel analytical system comprised of in-line permselective membrane separation and on-line ICP-MS measurement is aimed to be introduced in this study. Because of trace elements and sodium are all cations, a selective chelating agent, named EDTA, was added to form anionic EDTA complexes with analyte ions. However ion exchange mechanism need to keep the charge equilibrium, a lot of sodium ions can be removed to strip solution and hydrogen ions entered the sample cell from the strip solution. This process will reduce the pH from 7 to 2 and the elements combined with EDTA will be substituted by hydrogen ions. By the way of using basic 650mM NH4Cl as strip buffer, a lot of NH4+ will replace with H+ to avoid the pH decreasing. Over 99.9% of 9000 ppm NaCl can be removed and the interferences caused by dissolved salts can be completely eliminated. The robustness of proposed method is expected to be satisfactory for the long-term analysis of high salt content samples and the recovery of analyte elements can maintain 100±10%.Based on the currently obtained results, a hyphenation system comprised of in-situ microdialysis sampling, in-line membrane separation and on-line ICP-MS measurement is expected to be established for continuouslym, in-vivo and in-situ monitoring the dynamic variation of trace elements in a living animal.