Deductive prediction of measurement precision and optimization of integration time and wavelength in capillary electrophoreses

Abstract

This paper demonstrates that the relative standard deviation (RSD) of measurements in a capillary electrophoresis system can be predicted theoretically from the baseline and the signal shape at low sample concentration. The only requirements for prediction of the uncertainty are the Fourier transform of the baseline (here 2048 data points) and the observation of signal shape. The micellar electrokinetic chromatography (MEKC) of acetaminophen and caffeine is taken as an example. The optimum is defined here as the condition of the lowest RSD or highest precision. The optimum single wavelength is selected from between 220 and 350 nm for the MEKC system equipped with a photodiode array detector. The optimum time domain of signal integration is shown to be even narrower than the entire signal region, providing an RSD value about half that for integration of the entire region. The theory is in good agreement with observed RSD values.