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Evaporative light scattering detection for in‐line monitoring of stopped‐flow liquid chromatography–nuclear magnetic resonance analysis of compounds with weak or no chromophore groups
Author(s) -
Petritis Konstantinos,
Gillaizeau Isabelle,
Elfakir Claire,
Dreux Michel,
Petit Alain,
Bongibault Nelly,
Luijten Wim
Publication year - 2002
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/1615-9314(20020601)25:9<593::aid-jssc593>3.0.co;2-f
Subject(s) - chromophore , chemistry , chromatography , chromatography detector , amino acid , nuclear magnetic resonance spectroscopy , proton nmr , analytical chemistry (journal) , high performance liquid chromatography , photochemistry , organic chemistry , biochemistry
Abstract This study demonstrates the use of the evaporative light scattering detector (ELSD) as an in‐line monitoring detector for the stopped‐flow liquid chromatography–nuclear magnetic resonance (LC–NMR) analysis of compounds with weak chromophore groups or none at all. The instrumentation set‐up is discussed and the system is compared with the more common ultraviolet (UV) monitoring detection method. Underivatized amino acids without a UV chromophore (taurine) or with weak UV chromophores (hydroxyproline, aspartic acid, glycine, etc.) were selected as model compounds. The isocratic separation of the amino acids was achieved by using 0.5 mM pentadecafluorooctanoic acid (PDFOA) in deuterium oxide (D 2 O), on a Purospher RP‐18e stationary phase column. PDFOA was particularly suitable for ion‐pairing and NMR detection, due to the absence of protons in the alkyl chain, as well as the required low concentration. ELSD proved an interesting mode of chromatographic detection prior to NMR, due to its universality (no UV chromophore is needed). LC–NMR allowed the direct analysis of amino acids without the use of any particular NMR sequences (e.g. for the suppression of interfering resonances).