Benefits of the pretreatment step in purifying water for LC-MS analyses
C. Regnault, S. Mabic
LC-GC The Column
Vol 1 issue 9
12-15
2004
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Solvent and reagent quality has long been a topic of interest to analytical chemists using liquid chromatography. While several articles describe chromatography methods, few references address the purity of solvents used to prepare mobile phases. Some data to support the water quality suitable for HPLC and LC-MS analysis have been presented previously, but little has been published on the means required to achieve such water quality. Starting from a customer case study, data reported here show the benefits of optimizing each step of the water purification process. Indeed, water purification can be divided into two major basic steps, the pre-treatment step and the polishing step. Since water delivered at the final purification stage is used to prepare the mobile phase,it seems to be an obvious target for optimization., However, the initial pretreatment step is equally critical. Several pretreatment technologies are discussed for their ability and suitability to be utilized in complete water purification processes dedicated to produce water for HPLC and LC-MS work. | Benefits of the pretreatment step in purifying water for LC-MS analyses
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Qualification of an electro-deionization module via experimental design and ion chromatographic studies
E. Castillo, D. E. Coleman, D. Darbouret, T. Dimitrakopoulos, E. Feuillas, L. E. Vanatta
Journal of Chromatography A
1039
63-70
2004
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To meet the needs of the laboratory-water market, a modified electro-deionization (EDI) module has been developed to produce Type 2 purified water. An EDI module consists of desalting and concentrating fluidic compartments that are both filled with anion and cation ion-exchange resins; an anode and a cathode electrode are at opposite ends. In the design in this research, the anode electrode is segmented into three parts and individual dc amperages are applied to each segment; the cathode electrode is a single common electrode. Critical to the performance and longevity of this type of EDI module are: (1) the optimization of the applied dc amperages and (2) the ionic mass balance (i.e., the concentrations of specific and total ions of the RO feedwater to the module compared to the concentrations in the water exiting the module via the desalting and concentrating compartments). To determine a suitable current for each electrode pair, a full-factorial experimental design was developed and employed. For the application of this combination of amperages, the critical parameter of specific-ion mass balance was determined using ion-chromatographic measurements. | 15250404
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