Characterization of microwave-induced plasma as a detector for supercritical fluid chromatography

Abstract

A microwave-induced plasma (MIP) sustained In helium Is evaluated as an element-selective detector for capillary supercritical fluid chromatography (SFC). The plasma source, a surface-mlcrowave-lnduced plasma (surfatron), Is described. Optimal plasma conditions Including viewing position, helium flow rate, and applied microwave power are discussed for sulfur emission In the near-infrared spectral region. In addition, the effects of two common mobile phases (C02 and N20) on plasma stability, sensitivity, and spectral background from 200 to 1100 nm are assessed. Although the plasma was evaluated principally for use with SFC, much of the discussion Is relevant to Its application as a gas chromatographic detector.Capillary gas chromatography (GC) and capillary liquid chromatography (LC) possess inherent liabilities that make them unsuitable for many types of separations. The former is ultimately restricted by the limited volatility and thermal lability of many organic compounds. The latter is restricted

Atomic spectroscopy with surface wave plasmas

“…The use of a plasma detector in this area requires the ability to produce a mixed gas plasma without sacrificing the analytical performances. Initial experiments with surface wave plasmas as detectors in supercritical fluid chromatography [38][39][40] have shown that a helium-carbon dioxide plasma provides a lower sensitivity for several non-metal analytes than a pure helium plasma. This can be corrected and our own experiments show that for the tin detection in supercritical fluid chromatography, the use of a ternary plasma (He -CO 2 -H 2 ) not only allows the recovery of the analytical sensitivity of the pure helium plasma, but also improves it (Fig.…”

Easy hyphenation of supercritical-fluid chromatography to atomic-emission detection for analysis of lubricant additives

“…Successful coupling of either packed or capillary SFC to a modified Beenakker [11], a surfatron [12,13], and microwave plasma torch cavities [14,15] has been described in the literature; the aim of these works was to enable selective detection of compounds containing sulfur [16], chlorine [17 20], and bromine [12,13,18]. In contrast with previous SFC-MIP-AED systems, which were home-made devices, a commercial MIP-AED instrument has recently been successfully hyphenated to packed-column SFC without the modification of the interface used for GC coupling.…”

Nitrogen‐selective detection in capillary supercritical fluid chromatography of derivatized oligosaccharides

“…While universal response of the flame ionization detector is advantageous in most applications, it is feasible to incorporate certain easily detectable elements during a derivatization step. This strategy has been used in our previous work on thermionic detection of derivatized a-ketoacids 151, steroids 161, and prostaglandins [7], In addition, the element selectivity of a microwave plasma detector [8,9) was explored with the boronate derivatives of certain carbohydrates [ 101. In this communication, we report on the use of nitrogen-sensitive thermionic detector for improved detection of appropriately derivatized oligosaccharides and glycoproteinderived fragments.…”