An Integrated Amperometry Waveform for the Direct, Sensitive Detection of Amino Acids and Amino Sugars Following Anion-Exchange Chromatography

Abstract

This paper describes a new detection method that uses a six-potential waveform to detect all amino acids without derivatization. The detection limits are less than 1 pmol for most of the analytes. The anion-exchange separation uses a ternary gradient with water, 0.25 M sodium hydroxide, and 1.0 M sodium acetate. We present results of waveform optimization experiments designed to minimize gradient artifacts and to achieve optimum conditions for the quantitative analysis of common amino acids. Analytical results for protein hydrolysates are discussed and compared with those obtained by cation exchange followed by ninhydrin derivatization and spectrophotometric detection.

Comparative study on the analytical performance of three waveforms for the determination of several aminoglycoside antibiotics with high performance liquid chromatography using amperometric detection

“…The quadruple-potential waveform in this paper was the same as we used before [17] and it is involved in the use of a negative cleaning potential instead of a relatively long period of high positive cleaning potential, which minimizes the problem of electrode recession and improves the sensitivity and reproducibility. The six-potential waveform chosen in this paper was derived from the waveform introduced by Clarke et al [18] for the integrated pulsed amperometry detection of amino acids and amino sugars. After some preliminary optimization conducted by varying single potential while keeping the other parameters of waveforms constant, we achieved a fairly perfect six-potential waveform as shown in Fig.…”

“…But we noticed that with regard to many analytical performances such as detection sensitivity, the modified quadruple-waveform is only slightly better than the triple-potential waveform. Considering that the oxidation of the gold at the electrode surface definitely occur and the current from this process always contributes to the background, baseline noise and then results in poor sensitivity and reproducibility, to enhance signal and reduce baseline noise, Clarke et al [18] introduced a six-potential waveform based integrated amperometry to detect amino acids. Unlike pulsed amperometry, in integrated amperometry, the potential during current sampling is not held constant but it is scanned between a high and low value.…”

Optimizing the Quadruple‐potential Waveform for the Determination of Gentamicin Sulfate by High Performance Liquid Chromatography with Pulsed Electrochemical Detection

“…However, the hydroxyl and amino groups of its molecule structure present the possibility of detecting gentamicin by electrochemical method as used for the determination of amino acids and carbohydrate. [22][23][24][25][26][27][28][29][30][31][32][33] Several papers have been published for the determination of gentamicin by HPLC with pulsed amperometric detection (PAD). 4,34 In these methods, gentamicin can be separated by HPLC and then oxidized and detected at gold electrodes in a high pH solution.…”

“…To overcome this disadvantage, Jensen et al 35 and Rocklin et al 22 advanced a novel quadruple-potential waveform and applied it successfully to detection of carbohydrates. Clarke et al 23 further developed this quadruple-potential waveform to six-potential waveform for the detection of amino acids and amino sugars. In these methods, a high negative potential instead of a high positive potential was adopted to clean the electrode fouling from oxidized analytes.…”

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

“…The resulting 50% al. [12] developed an integrated amperometry wavesolution was kept undisturbed for 24 h to allow the form for the direct detection of amino acids using sodium carbonate to settle at the bottom prior to the high-performance anion-exchange chromatography last dilution step to 250 mM. The 1 M sodium (HPAEC) and integrated pulsed amperometric deacetate mobile phase was prepared by dissolving an tection (IPAD).…”