Anions retention times

Anion Retention time (min) UV active UV detection limite (mg L 1) UV detector position Wavelength (nm)... 

Table 6.7. Comparison of anion retention times with benzoic acid and potassium benzoate eluents that have the same benzoate ion concentrations. (From Ref. 113]).

Xianren, Q., Chong-yu, X., and Baeyens, W., Computer-assisted predictions of resolution, peak height and retention time for the separation of inorganic anions by ion chromatography, ]. Chromatogr., 640, 3, 1993. 

Havel, J., Madden, J. E., and Haddad, P. R., Prediction of retention times for anions in ion chromatography using artificial neural networks, Chromatograph-ia, 49, 481, 1999. 

In comparing the three chromatograms, it is apparent that the general shape of the elution profile is the same for all the three runs. Numerous peaks appear within the first 12 min of anion-exchange retention time in all three 2D chromatograms. These correspond to the proteins that were not-retained or very weakly retained on the anion-exchange column, which implies that they are the most basic proteins in the sample. 

A similar set of conditions was utilized by Reif et al.76 to analyze folic acid, using leucovorin as an internal standard. Other authors77 have used similar conditions to study extensively the identity of possible leucovorin contaminants. In addition to these partition /ionization surpression methods, anion exchange hplc has been used to separate CF from other naturally occurring folates,78 and some correlation has been made between the number of glutamyl residues and retention time. 

A high-performance liquid chromatographic method for nalidixic acid on a strong anion-exchange resin column has been reported, using a mobile phase of 0.01 M sodium tetraborate at pH 9.2 and 0.003 M sodium sulfate. The relative retention time for nalidixic acid in the system reported by Sondach and Koch was 0.86 with sulfanilic acid as the standard at... 

The presence of fluoride or chloride in the sample does not interfere with the formic acid analysis. Retention time for these ions under the stated conditions are F (5.4 minutes) and Cl (29 minutes). Sulfate ion is retained for a longer time. Ultimately, these anions are eluted and may interfere with subsequent samples. Generally, these highly retained anions show very broad peaks, which are easily distinguished from the organic acid peaks. 

Ion chromatography is very promising for ocean measurements. Anions and cations with concentrations below parts per billion can be separated and detected. The chromatographic retention time provides information on the chemical form of the ion, its oxidation state, and whether it is complexed with another material. 

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