Alkali metals, alkaline earths and anions

Jones and Tarter [11] have applied this technique to the simultaneous determination of metals (sodium, potassium, calcium, magnesium) and anions (chloride, sulphate, nitrate, bromide) in potable waters. The technique uses a cation separator column, a conductivity detector, an anion separator column and an anion suppressor column. Two different eluants were used lithium carbonate-lithium acetate dihydrate, and copper phthalate. 

All water samples were injected and analysed as received without prior preparative steps. 

The normal procedure for the use of the ion chromatograph was followed, with the exception of the use of the electrochemical detector after the anion suppressor. The solutions were injected and the detector and chart recorder were adjusted to provide peaks of appropriate height. 

The operating parameters for the two eluants are listed in Table 2.20. For the detection of monovalent actions and anions, a basic eluant, lithium carbonate-lithium acetate, is used. Analysis of divalent cations and anions involves the use of an acidic copper phthalate eluant. 

Simultaneous analysis of both anions and cations indicates that water samples from various localities contain many of the same ions but in differing amotints. Fig. 2.24 illustrates typical chromatograms of tap water and rain water. 

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