Some factors affecting separation and detection of amino acids by high-performance anion-exchange chromatography with integrated pulsed amperometric detection

Abstract

Some factors influencing the separation and detection of amino acids by high-performance anion-exchange chromatography with integrated pulsed amperometric detection were investigated. These factors include eluent concentration, column temperature, and detection waveform. The selectivity changes in weakly retained amino acids are slight with changing sodium hydroxide eluent concentration. When sodium acetate eluent concentration is changed, the selectivity variations between strongly retained amino acids containing two carboxyl groups and containing only one carboxyl group are obviously different. Significant but slight selectivity changes in weakly retained amino acids can be achieved through changing the column temperature. Sodium hydroxide and sodium acetate eluent concentration affect the detection of amino acids. Detection sensitivity of amino acids can be improved by increasing the concentration of sodium hydroxide and sodium acetate in a certain concentration range. The detections of amino acids at two different detection waveforms were compared. The hydroxyl amino acids can be selectively detected by choosing a modified detection waveform. The optimized gradient elution condition and column temperature for analyzing 19 amino acids were obtained. The time for the gradient elution program was 60 min. The column temperature was 35 8C. Under the optimized conditions, detection limits for 19 amino acids were 0.15-4.52 pmol. The calibration graphs of peak area for all the analytes were linear for about three orders of magnitude. The RSDs (n55) of peak area were 0.6-5.6%. The determination of trace amino acid impurities in valine product is shown as an application example. 

Isotope ratio monitoring of small molecules and macromolecules by liquid chromatography coupled to isotope ratio mass spectrometry

“…To date, the analysis of free amino acids by reversed‐phase LC is usually performed after derivatisation with non‐polar reagents such as fluorescent 9‐fluorenylmethyl carbonate. For underivatised amino acid analysis, most of the methods involve anion‐exchange chromatography or ion‐pair reversed‐phase chromatography 28, 29. However, in practice, the addition of organic modifiers, the derivatisation steps, and the basic pH used, are not appropriate for accurate isotopic analysis by irm‐LC/MS.…”

Effect of temperature on the retention of amino acids and carbohydrates in high-performance anion-exchange chromatography

“…In our previous publications we reported the determination of amino acids and carbohydrates by HPAEC-IPAD [6,7,34]. This paper presents temperature effects in high-performance anionexchange chromatography of amino acids and carbohydrates.…”

Stochastic biosensors based on N- and S-doped graphene for the enantioanalysis of aspartic acid in biological samples

“…7 To date, different methods were proposed for the analysis of Asp. 8 These methods include: thin layer chromatography, 9 gas chromatography, 10 high performance liquid chromatography, 11 chiral ligand-exchange capillary electrophoresis, 12 spectrophotometry, 13 uorimetry, 14 and electrochemistry. 15 Due to the simplicity and low cost of an electrochemical method, it is necessary to develop an electrochemical system that is both highly selective and sensitive for the aspartic acid investigation.…”