A Comparison of the Properties of Contactless Conductivity and Diode‐Array Photometric Detectors in Analyses of Low‐Molecular, Biologically Active Substances by Capillary Electrophoresis in Acetic Acid Solutions

Abstract

The performance of the contactless conductivity (C 4 D) and diode array photometric (DAD) detectors has been compared for CE separations of creatinine, arginine and 3-methylhistidine in acetic acid background electrolytes. The contactless conductivity detector response has also been modeled. It has been found that the two detectors provide similar responses and can readily be used for dual CE detection. Changes in the acetic acid concentration affect the C 4 D noise less than the DAD noise, but their effect on the C 4 D response to the analytes is greater than with DAD. In general, C 4 D provides better detection results at higher acetic acid concentrations, while DAD is more sensitive and reliable at very low ones. Capillaries with greater internal diameters are preferable for both detectors, provided that the separation efficiency is not adversely affected. Acetic acid is a suitable background electrolyte for CE separations of small, basic organic molecules.

Enantioseparation of tartaric acid by ligand‐exchange capillary electrophoresis using contactless conductivity detection

“…Also, the response of CCD is strongly dependent on parameters such as effective mobility of BGE constituents and its conductivity. Opekar et al studied the effect of capillary diameter on CCD performance and they found that 75 μm id provides the best response regarding detection limits . For such reasons the same capillary diameter was employed in this work.…”

The Dependence of the Sensitivity and Reliability of Contactless Conductivity Detection on the Wall Thickness of Electrophoretic Fused‐Silica Capillaries

“…5 in [15]). This is parasitic signal transfer between the electrodes and it can be seen in Figure 2 that the experimental dependences confirm the modeling results, the crosstalk capacitance is not affected by the capillary wall thickness.…”

“…It follows from these dependences that the response first rapidly increases with increasing MES/His concentration, attains a maximum and then slowly decreases. This course is characteristic of C 4 D, whose conductivity response is a complex function of both the BGE conductivity and the permittivity (for details see [15]). The decrease in the sensitivity at higher BGE concentrations also follows from the detection cell calibration (see Fig.…”

“…The commonly attained limits of detection (LOD) are around 1 mM for most inorganic and organic analytes [6,14]. The sensitivity of C 4 D is fully comparable with that of UV photometric detectors which are by far most common in CE [15].…”

Determination of the spectrum of low molecular mass organic acids in urine by capillary electrophoresis with contactless conductivity and ultraviolet photometric detection—An efficient tool for monitoring of inborn metabolic disorders

“…For this purpose, a combination of two independent detection techniques is tested, namely, the universal C 4 D and selective UV photometry. The C 4 D/UV combination has already been used several times in CE, for determination of model samples of cyclodextrins and their derivatives [29], for analyses of mixtures of creatinine (Crea), 3-methylhistidine and arginine [30], for quantitation of mixed peaks of amino acids in a vitamin complement hydrolyzate [31], for determination of inorganic cations and organic acids in a multivitamin complement [32], and for determination of inorganic and organic anions in white wine [33]. To our knowledge, the C 4 D/UV combination has not yet been applied to analyses of OA profiles in complex clinical samples.…”