Effect of suppression efficiency on sensitivity in ion chromatography

• Published in: Journal of Chromatography A 1988-05, Vol.439 (1), p.151-157
• Main Authors: Tian, Z.W., Hu, R.Z., Lin, H.S., Hu, W.L.
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Chemistry; Chromatographic methods and physical methods associated with chromatography; Exact sciences and technology; Other chromatographic methods
• ISSN: 0021-9673
• DOI: 10.1016/S0021-9673(01)81683-6

The ionization equilibrium is calculated for a suppressor effluent containing remnant ions, e.g., Na + in the case of anion analysis, due to imperfect suppression. It is shown that: (1) The remnant ion not only affects the background specific conductivity but also seriously depresses the peak height of samples of low concentration. The practical peak height may be much less than the ideal peak height. For P K HA > 11, the practical peak height may be negative. (2) The sensitivity, linearity and reproducibility of conductivity detection for low concentration samples are seriously affected by the remnant ion, i.e., by the conversion efficiency of the suppressor. (3) The ionization of the weak acid derived from the eluent is depressed by the common ion effect of the strong acid derived from the sample. The peak height depression depends on the ionization constant, K HA. However, in the case of C Na > 0, the buffer effect of compensates the effect of remnant Na +. Therefore it is appropriate to use an eluent with P K HA in the range 6–8.