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DOSY of sample‐limited mixtures: comparison of cold, nano and conventional probes
Author(s) -
Bradley Scott A.,
Paschal Jonathan,
Kulanthaivel Palaniappan
Publication year - 2005
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1504
Subject(s) - chemistry , analytical chemistry (journal) , sample (material) , signal (programming language) , qualitative analysis , flow (mathematics) , nano , chromatography , chemical engineering , qualitative research , social science , geometry , mathematics , sociology , computer science , programming language , engineering
The DOSY analysis of dilute mixtures can be a challenge because a high signal‐to‐noise ratio is required for the best DOSY results. The sensitivity increase gained from new probe technologies (e.g. cold and nano probes) could enable one to acquire good DOSY spectra on sample amounts too low for conventional probes. In this article, we investigated the performance of cold and nano probes for qualitative DOSY analysis of concentrated and sample‐limited mixtures, and compared the results with those of the conventional probe. We first measured the fluid flow for each probe. All three probes exhibited only relatively small levels of flow; consequently, a double‐stimulated echo pulse sequence was not employed in the subsequent DOSY experiments. This decision was based on three facts: (1) flow‐induced phase distortions were not observed, (2) our intentions are only to perform qualitative mixture analysis, and (3) discarding 50% of the already limited signal cannot be afforded. Although the cold and nano probes produced DOSY results for the concentrated mixture that were inferior to the conventional probe, the increase in the signal‐to‐noise ratio observed with these probes proved to be advantageous for the dilute three‐component mixture. Furthermore, the cold probe showed slightly superior performance over the nano probe; thus, we conclude that among the probes examined the cold probe is best suited for qualitative DOSY analysis of sample‐limited mixtures. Copyright © 2004 John Wiley & Sons, Ltd.