The use of liquid chromatography for the analysis of metal ions in aqueous solutions and for the determination of water in organic matrices

摘要

The value of a p-phenylenediammonium eluent in single-column ion chromatography is demonstrated. It is shown to be particularly useful for separating trivalent aluminum from common divalent metal ion interferences. The aluminum is detected with a conductivity detector;Postcolumn reaction in liquid chromatography is reviewed. The application of disodium 1-(2-thiazolylazo)-2-naphthol-3,6-disulfonate (TAN-3,6-S) to the detection of metal ions in single-column ion chromatography with a visible absorbance detector is explored. TAN-3,6-S is shown to complex a large number of metal ions. It is a particularly useful postcolumn reagent because by the judicious selection of effluent pH, selectivity may be introduced into the detection system;Temperature is shown to affect the retention times of divalent and trivalent metal ions in ion chromatography. Factors contributing to this phenomenon are examined, and enthalpy changes for several ion-exchange reactions are calculated and compared. Several chromatographic separations are improved by operating the system at elevated temperature;Two methods for the determination of water in organic matrices using liquid chromatography and a spectrophotometric detector are presented. Both employ a chromatographic separation by ion-exclusion. The first detection method makes use of solvatochromism, the shift in an organic spectrum which occurs as solvent polarity is changed. This second detection method uses a solid-phase postcolumn reactor containing a cation-exchange resin in the H[superscript]+ form. This reactor acts as catalyst for a reaction occurring between water and two components of the mobile phase, methanol and trans-cinnamaldehyde. In the reactor, an equilibrium is established between cinnamaldehyde and methanol, which form an acetal and water. The presence of water in a sample causes the equilibrium to shift back towards the cinnamaldehyde, causing an increase in absorbance when the spectrophotometric detector is set at a wavelength where cinnamaldehyde absorbs. ftn[superscript]1DOE Report IS-T-1373. This work was performed under contract No. W-7405-Eng-82 with the Department of Energy.