Sensitive determination of carbohydrates labelled with p‐nitroaniline by capillary electrophoresis with photometric detection using a 406 nm light‐emitting diode

Abstract

p-Nitroaniline was explored as a derivatising reagent for UV absorbance detection of carbohydrates after separation by CE. This derivatising agent has three advantages: first, it has excellent water solubility; second, it has high molar absorptivity; and third, it is possible to obtain sensitive detection using a UV or blue light-emitting diode (LED) as the light source. The labelling reaction took less than 30 min to complete with high reaction yield. The separation process was modelled and optimised using an artificial neural network. Nine carbohydrates were separated by a CE system within 16 min using a 0.17 M boric acid buffer at pH 9.7. On-column LED detection at 406 nm allowed the detection of carbohydrates with good detection limits (<1.1 microM or 8.8 fmol) and reproducible quantification in the concentration range of 2.6-200 microM. This method was applied successfully to the determination of component carbohydrates in some food samples.

Recent advances in the application of capillary electromigration methods for food analysis

“…Momenbeik et al [61] used the LED detection system coupled to CZE to determine carbohydrates derivatized with p-nitroaniline in food samples. Several parameters affecting the separation selectivity were studied using an artificial neural network able to predict mobilities including as response factor the quality of the final separation.…”

Light‐emitting diode‐compatible probes for indirect detection of anions in CE

“…Examination of the literature and recent experience with p-nitroaniline [20] suggested that small aromatic compounds containing a nitro group would have some absorbance in the near UV region and would be compatible with a UV LED detector. Through a comprehensive review of both scientific literature and commercial product catalogues, a number of nitro-aromatic compounds that had one or two ionisable sites (hydroxy and carboxylic acid groups) were selected.…”

Derivatization of carbohydrates for analysis by chromatography; electrophoresis and mass spectrometry

“…These are listed in Table 1. p-Nitroaniline (26) was said to have three advantages as a derivative for capillary electrophoresis (CE); it has excellent water solubility; second, it has high molar absorptivity; and third, it is possible to obtain sensitive detection using a UV or blue light-emitting diode (LED) as the light source [147]. Nine monosaccharides were separated by a CE system within 16 min using a 0.17 M boric acid buffer at pH 9.7.…”