Selective Analysis of Secondary Amines Using Liquid Chromatography with Electrochemical Detection (LC‐EC)

Abstract

In a mixture of primary and secondary aliphatic amines, the primary amines were derivatized (masked) with ophthalaldehyde (OPA) followed by derivatization of the remaining secondary amines with ferrocenecarboxylic acid chloride (FAC). The "tagged" amines were analyzed by LC-EC (liquid chromatography with electrochemical detection) using in-series dual electrode detection. Chemically-reversible oxidation of the FAC tagged secondary amines and their subsequent complementary oxidation and reduction signals coupled with chemically-irreversible oxidation of OPA tagged primary amines provided the selectivity for quantitative secondary amine analysis. The procedure was also applied for the selective identification of fragment 4 -11 (N-terminus-proline) of Substance P in the presence of other Substance P fragments with primary amino acids as their N-termini.

Dual Electrode Detection in LC‐EC Analysis of Sanger‐tagged Amino Acids: Electrochemical Reduction of Aromatic Nitro Groups

“…Advantages of dual electrode in series versus single electrode detection has been addressed by Roston and Kissinger and include increased selectivity and sensitivity [31]. We have used dual electrode to impart selectivity in analysis [14] and will address increased sensitivity with our results herein. We began with fundamental studies using cyclic voltammetry at stationary, rotating disk and rotating ring disk electrodes on model compounds nitrobenzene (NB) and N-methyl-2,4-dinitroaniline (NMDNA).…”

“…, we determined the collection efficiency for our system was 37 %. This can be compared to 37 % for flow rates of 0.3 to 1.6 mL / min for hydroquinone [31] and 30 to 50 % depending on flow rate from our work with ferrocene tagged amino acids [14].…”

Construction of Transition Metal Coordination Polymers with Free Carboxyl Groups and Turn-On Fluorescent Detection for α,β-Diamine

“…Furthermore, as water pollutants, they can be assimilated into the human body through the digestive system, which could lead to biological enzymes being inactivated and then resulting in poisoning or even cancer . So far, the ways for the detection of organic amines are based on traditional gas and/or liquid chromatography, mass spectrometry, electrochemical method, as well as biological small molecule probe; all of these methods are high cost, long cycle, and complicated operations. − For this reason, developing a convenient and economical method to detect low molecular weight α,β - diamine is of great significance.…”

Selective Analysis of Secondary Amino Acids in Gelatin Using Pulsed Electrochemical Detection

“…Another technique commonly used in HPLC applications has been to block or "mask" primary amino acids by derivatization with o-phthalaldehyde (OPA) in the presence of a thiol followed by an additional derivatization with a reagent to produce fluorescent [29][30][31][32][33][34][35][36] or electrochemically active adducts. 37 Although these approaches have been successful, stability of the amino acid derivatives remains an issue. The use of IPAD eliminates the stability issues often encountered when using fluorescence detection in amino acid analyses.…”

“…Precolumn derivatization with reagents that produce fluorescent adducts has been used for determination of secondary amino acids in urine and tissue samples. − However, these reagents lack specificity for secondary amino acids and require a degree of kinetic control during derivatization to improve selectivity. Another technique commonly used in HPLC applications has been to block or “mask” primary amino acids by derivatization with o -phthalaldehyde (OPA) in the presence of a thiol followed by an additional derivatization with a reagent to produce fluorescent − or electrochemically active adducts . Although these approaches have been successful, stability of the amino acid derivatives remains an issue.…”