PREDICTION OF NONLINEAR GRADIENT SIGNAL IN ION CHROMATOGRAPHY BASED ON “EXPERIMENT-FREE” METHODOLOGY

Abstract

One of the strategies that might be applied in ion chromatographic (IC) multi-segment gradient optimization is the simplification of gradient profile and its approximation by nonlinear elution. This work describes the IC signal modeling strategy for linear and nonlinear gradients. The performance characteristics of developed models do not depend on the linearity of gradient profile, but rather on initial gradient of eluent competing ion concentration. Four different IC models were developed and tested, requiring three, two, or single experimental data points. Moreover, a model based on “experiment-free” methodology using standard column manufacturer quality assurance documents was developed. It is shown that all the developed models have good predictive ability that decreases by reducing the model complexity and number of experimental data required. However, even the “experiment-free” methodology offers reasonable performance characteristics (average of relative error 4.99%) and might be recommended for IC method development purposes.

Keywords:

• ion chromatography
• nonlinear gradient
• signal prediction

ACKNOWLEDGMENTS

This study is a part of the research projects: “Ion Exchange Processes in Industrial Water Quality System,” 125-1253092-3004, and “Bioceramic, Polymer and Composite Nanostructured Materials,” 125-1252970-3005, supported by the Ministry of Science, Education, and Sports of the Republic of Croatia. The authors are grateful for this support.

The authors thank Dionex Corporation, Sunnyvale, CA, USA, for the technological support needed for experimentation and, particularly, Dr. Nebojša Avdalović for his valuable recommendations and suggestions.