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On-line liquid chromatography-mass spectrometry of ion pairs

1981; Elsevier BV; Volume: 203; Linguagem: Inglês

10.1016/s0021-9673(00)80288-5

1873-3778

Daniel P. Kirby, Paul Vouros, Barry L. Karger, Bruce J. Hidy, B.A. Petersen,

Biochemical Analysis and Sensing Techniques

An on-line continuous extraction interface between a high-performance liquid chromatograph and a mass spectrometer permits the operation of the chromatograph in the reversed-phase mode without compromising the performance of the spectrometer. Solutes are extracted into a volatile organic solvent which is then transported to the spectrometer by a moving-belt interface. A greatly simplified version of the original extraction interface is shown. In its new design the extractor operates on the principle of solvent rather than air segmentation, and much of the expensive peripheral equipment has been eliminated. Flow-rates of up to 1.0 ml/min each of aqueous (mobile) and organic (extracting) phases are easily accommodated in this on-line operation. We have examined the compatibility of ion-pair chromatography with the high-performance liquid chromatography-extraction-mass spectrometry combination, particularly in terms of the quality of solute spectra obtained and the volatility of the counter ions. The results presented here show that ion pairing and subsequent extraction are compatible with the on-line operation under both chemical ionization and electron impact conditions. Spectra are produced from the ion pairs which consist of the solute spectrum superimposed on but easily discerned through the spectrum of the counter ion. A rationale to explain the mass spectrometric observations is presented. The implication of these results for the analysis of ionic compounds by this technique is discussed.