Ion chromatography with the indirect ultraviolet detection of alkali metal ions and ammonium using imidazolium ionic liquid as ultraviolet absorption reagent and eluent

Abstract

Indirect ultraviolet detection was conducted in ultraviolet-absorption-agent-added mobile phase to complete the detection of the absence of ultraviolet absorption functional group in analytes. Compared with precolumn derivatization or postcolumn derivatization, this method can be widely used, has the advantages of simple operation and good linear relationship. Chromatographic separation of Li(+) , Na(+) , K(+) , and NH4 (+) was performed on a carboxylic acid base cation exchange column using imidazolium ionic liquid/acid/organic solvent as the mobile phase, in which imidazolium ionic liquids acted as ultraviolet absorption reagent and eluting agent. The retention behaviors of four kinds of cations are discussed, and the mechanism of separation and detection are described. The main factors influencing the separation and detection were the background ultraviolet absorption reagent and the concentration of hydrogen ion in the ion chromatography-indirect ultraviolet detection. The successful separation and detection of Li(+) , Na(+) , K(+) , and NH4 (+) within 13 min was achieved using the selected chromatographic conditions, and the detection limits (S/N = 3) were 0.02, 0.11, 0.30, and 0.06 mg/L, respectively. A new separation and analysis method of alkali metal ions and ammonium by ion chromatography with indirect ultraviolet detection method was developed, and the application range of ionic liquid was expanded.

Separation and indirect ultraviolet detection of ferrous and trivalent iron ions by using ionic liquids in ion chromatography

“…In IUV detection, the selection of the UV absorption reagent is very important. Nicotinamide and 4‐aminophenol hydrochloride are the common UV absorption reagents , and pyridinium and imidazolium ILs with strong UV absorption can also be used as the UV absorption reagents . The effects of niacinamide, 4‐aminophenol hydrochloride, and two ILs ([EMIm][BF 4 ] and [EPy][BF 4 ]) as the UV absorption reagents on the determination of Fe 2+ and Fe 3+ were investigated.…”

“…In IUV detection, the selection of the UV absorption reagent is very important. Nicotinamide and 4-aminophenol hydrochloride are the common UV absorption reagents [42], and pyridinium and imidazolium ILs with strong UV absorption can also be used as the UV absorption reagents [16][17][18][19][20][21][22] 4 ] were used as the UV absorption reagent, respectively, the two iron ions could be completely separated with a good peak shape. When 4-aminophenol hydrochloride and nicotinamide were used as the UV absorption reagent, respectively, the two iron ions could not be separated, and the baseline noise value was large when nicotinamide was used as the UV absorption reagent.…”

“…Compared with the pre‐column and post‐column derivatization, IUV detection is simple, easy to operate and realize. In recent years, some studies on the detection of cations and anions without UV absorption by using IUV detection have been reported.…”

“…Compared with the pre-column and postcolumn derivatization, IUV detection is simple, easy to operate and realize. In recent years, some studies on the detection of cations [17][18][19] and anions [20][21][22] [23]. ILs have some unique physical and chemical properties, such as low melting point, strong dissolving ability, good stability, negligible vapor pressure, wide electrochemical window, etc.…”

Indirect ultraviolet detection of alkaline earth metal ions using an imidazolium ionic liquid as an ultraviolet absorption reagent in ion chromatography

“…Due to their unique properties, their use has attracted considerable interest, including an increasing number of publications on their use in preparing stationary phases of HPLC . An active research is found in many reports on the role of ILs to modify the retention of different types of solutes in LC . Based on their UV absorption, imidazolium ILs have been applied as background reagents for determination of IL cations in the HPLC and IC with UV indirect detection.…”