Investigation on liquid chromatographic separation of basic compounds using silica column with aqueous/organic mobile phase containing triethylamine and acetic acid

Abstract

A high-performance liquid chromatography (HPLC) method using silica column eluted with aqueous solvent mobile phase containing triethylamine (TEA) and acetic acid (ACH) at trace percentages was characterized for the analysis of basic compounds. The key mechanism of this system is ion-exchange accompanying interaction of silanol groups. The increase in the ACH concentration in the mobile phase minimizes the ionization of the silanol group, leading to reduced retention time. However, the greater extent of ionization of silanol caused by the increase of TEA concentration helps to retain basic compounds in the column. Further, the protonated TEA that is positively charged also competes for the ionized silanol group with basic compounds, resulting in the modification of retention time. On the other hand, the retention becomes longer with increasing proportion of either organic or aqueous solvent in mobile phase, and partial replacement of methanol with acetonitrile.

Novel Deliberately Sensitive and Selective Tetrahydrozoline Voltammetric Sensors Integrated with a Copper Oxide Nanoparticle/Zeolite Platform

“…Behavior of THZ at Different pH Values. THZ showed a pK a value of 10.5 65 ; therefore, it is expected that the electrochemical behavior of the THZ molecule at the CuONP/ZY electrode surface is pHdependent. As illustrated in Figure 4a, the oxidation potential of the recorded differential pulse voltammograms was shifted to more negative values at evaluated pH levels, assuming the participation of the protons in the electrooxidation of the THZ molecule.…”

Quantitative Explanation of Basic Compound Retention Mechanisms in Reversed-Phase Mode Liquid Chromatography

“…Further, N,N-dimethyloctylamine was also a beneficial additive [5]. Other additives were triethylamine [6], perchlorate [7], ammonium hydrogencarbonate [8], butyl-, pentyl-, hexyl-, cyclopentyl-, cycloheptyl-, and N,N-dimethyloctyl-amines, tributylmethylammonium chloride [9], and tetrabutylammonium [10].…”

“…As far as possible, please keep the introduction comprehensible to scientists outside your particular field of research. References should be numbered in order of appearance and indicated by a numeral or numerals in square brackets, e.g., [1] or [2,3], or [4][5][6]. See the end of the document for further details on references.…”

Precolumn fluorescence labeling method for simultaneous determination of hydroxyzine and cetirizine in human serum

“…Fluorescent products of both drugs were separated using a silica column with aqueous-organic mobile phase containing traces of acetic acid and triethylamine as a modifier (to control pH of the mobile phase) and the protonated form of triethtylamine functioned as a competing ion (Wu et al, 2004). This separation system has the advantage that basic compounds are strongly retained on the column and easily separated from largely excess reagent.…”