Lecture 10

Lecture 10 - Lecture 10 Cation Chromatography Chapter 23...

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Anal Chem 251 Lect 10 Cation Chromatography 1 Lecture 10 Cation Chromatography Chapter 23 Corresponding Lab: Ion Chromatography- Cations in Seawater
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Anal Chem 251 Lect 10 Cation Chromatography 2 Measurement of Ionic Solids in Seawater The first experiment you performed involved dissolved substances in filtered seawater. Aqueous solutions of ionic solids conduct electricity, the more ions, the greater the conductivity. In a later experiment, you will also measure the salinity of a sample of water with a salinity meter by measuring the electrical conductivity of the water. However, this won’t give any information on the nature of the ions.
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Anal Chem 251 Lect 10 Cation Chromatography 3 Cations in Seawater • There are different ions in seawater. The cations are: Na + , Mg 2+ ,Ca 2+ , and Sr 2+ . • We have already analyzed for Mg 2+ and Ca 2+ by a complexometric titration using EDTA. • With ion chromatography, we will analyze all cations at the same time, in the same manner that we analyzed the anions.
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Anal Chem 251 Lect 10 Cation Chromatography 4 Review of Chromatography The development of chromatography as an analytical tool began in 1903 when Mikail S. Tsweet, a Russian botanist, discovered that he could separate colored leaf pigments by passing a solution through a column packed with absorbent chalk particles. Tsweet named this new method chromatography (chroma = color, graphein” means to write )
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Anal Chem 251 Lect 10 Cation Chromatography 5 Review of Chromatography (Continued) • Chromatography is defined as the separation of components in a mixture by partitioning between a mobile phase and a stationary phase. The mobile phase is the eluent and the stationary phase is the column. • The eluent contains ions with similar characteristics of the analyte ions which compete with analyte ions for sites on the column.
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Anal Chem 251 Lect 10 Cation Chromatography 6 Ion Chromatography Since its introduction in the mid 1970’s, Ion Chromatography (IC) has become widely used as an analytical technique for the determination of polar and ionic species. Ion-Chromatography is a high-performance version of ion-exchange chromatography, with a key modification that removes eluent ions before detecting analyte ions. It is used in the semiconductor industry to monitor anions and cations at 0.1ppb in deionized water.
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Anal Chem 251 Lect 10 Cation Chromatography 7 Ion Chromatography Continued In ion chromatography, cations or anions are separated by ion exchange via an analytical column and detected by their electrical conductivity. The conductivity of the electrolyte in the eluent is ordinarily high enough to make it difficult or impossible to detect the conductivity change when analyte ions are eluted. The noise is greater than the signal. The concentration of the analyte is smaller than the eluent by a factor of 100 or more. Therefore, the key feature of suppressed-ion chromatography
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This note was uploaded on 04/27/2008 for the course CHEM 251 taught by Professor Vassilian during the Fall '06 term at Rutgers.

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Lecture 10 - Lecture 10 Cation Chromatography Chapter 23...

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