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Ionisation in the absence of high voltage using supercritical fluid chromatography: a possible route to increased signal

Ionisation in the absence of high voltage using supercritical fluid chromatography: a possible route to increased signal
Ionisation in the absence of high voltage using supercritical fluid chromatography: a possible route to increased signal
Supercritical fluid chromatography (SFC) is fast becoming a technique of choice for the analysis of a wide range of compounds and has been found to be complementary to high-performance liquid chromatography (HPLC). The combination of SFC and mass spectrometry (MS) affords a very useful tool in the separation and analysis of compounds. In this study the ionisation of samples in the absence of an applied electrospray voltage has been observed when using SFC/MS, with some compounds showing increased sensitivity when all ionisation source high voltage (HV) is removed. In an attempt to understand the mechanism of ionisation, a series of test compounds were analysed using standard electrospray ionisation (ESI) and atmospheric pressure chemical ionisation (APCI) source configurations and also different API source designs. In both cases, data were acquired with the applied high voltage on (normal conditions) or with the high voltage off, i.e. no voltage spray (novo-spray). The standards were analysed with a range of pressure and modifier percentage conditions. To understand the nature of the ionisation process observed, this was compared with three established liquid-to-gas ionisation mechanisms. These were thermospray (TSP), charge residue model (CRM) of ESI and sonic spray ionisation (SSI). Experiments were undertaken in an attempt to explain this ionisation phenomenon and quantify any observed change in sensitivity. The most important point to note is that enhanced ionisation was observed under novo-spray conditions in a SFC/MS configuration, which in certain cases provides a lowering in the overall limit of detection (LOD).
0951-4198
3673-3682
Thite, Mohini A.
ff1d15b2-9378-4f07-8085-57c626383ea3
Boughtflower, Robert
46c96e9d-9e08-42a5-b18f-3e6b1813433c
Caldwell, Jeff
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Hitzel, Laure
c6dd9747-b0ea-4164-b6d9-8ec258f8c9c4
Holyoak, Clare
3bdcf3d4-99c2-4de0-ba93-24865a9f079b
Lane, Stephen J.
c369f740-9242-4b6c-a7c5-0d4a3b65e497
Oakley, Paul
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Pullen, Frank S.
b40b2b0c-aa3d-4379-a062-4bce4e3709f4
Richardson, Stefan
c746499f-a882-42b3-b813-01f95087048e
Langley, G. John
7ac80d61-b91d-4261-ad17-255f94ea21ea
Thite, Mohini A.
ff1d15b2-9378-4f07-8085-57c626383ea3
Boughtflower, Robert
46c96e9d-9e08-42a5-b18f-3e6b1813433c
Caldwell, Jeff
b6504e0d-0ec8-4a6f-bf00-225d1c9632cd
Hitzel, Laure
c6dd9747-b0ea-4164-b6d9-8ec258f8c9c4
Holyoak, Clare
3bdcf3d4-99c2-4de0-ba93-24865a9f079b
Lane, Stephen J.
c369f740-9242-4b6c-a7c5-0d4a3b65e497
Oakley, Paul
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Pullen, Frank S.
b40b2b0c-aa3d-4379-a062-4bce4e3709f4
Richardson, Stefan
c746499f-a882-42b3-b813-01f95087048e
Langley, G. John
7ac80d61-b91d-4261-ad17-255f94ea21ea

Thite, Mohini A., Boughtflower, Robert, Caldwell, Jeff, Hitzel, Laure, Holyoak, Clare, Lane, Stephen J., Oakley, Paul, Pullen, Frank S., Richardson, Stefan and Langley, G. John (2008) Ionisation in the absence of high voltage using supercritical fluid chromatography: a possible route to increased signal. Rapid Communications in Mass Spectrometry, 22 (22), 3673-3682. (doi:10.1002/rcm.3784).

Record type: Article

Abstract

Supercritical fluid chromatography (SFC) is fast becoming a technique of choice for the analysis of a wide range of compounds and has been found to be complementary to high-performance liquid chromatography (HPLC). The combination of SFC and mass spectrometry (MS) affords a very useful tool in the separation and analysis of compounds. In this study the ionisation of samples in the absence of an applied electrospray voltage has been observed when using SFC/MS, with some compounds showing increased sensitivity when all ionisation source high voltage (HV) is removed. In an attempt to understand the mechanism of ionisation, a series of test compounds were analysed using standard electrospray ionisation (ESI) and atmospheric pressure chemical ionisation (APCI) source configurations and also different API source designs. In both cases, data were acquired with the applied high voltage on (normal conditions) or with the high voltage off, i.e. no voltage spray (novo-spray). The standards were analysed with a range of pressure and modifier percentage conditions. To understand the nature of the ionisation process observed, this was compared with three established liquid-to-gas ionisation mechanisms. These were thermospray (TSP), charge residue model (CRM) of ESI and sonic spray ionisation (SSI). Experiments were undertaken in an attempt to explain this ionisation phenomenon and quantify any observed change in sensitivity. The most important point to note is that enhanced ionisation was observed under novo-spray conditions in a SFC/MS configuration, which in certain cases provides a lowering in the overall limit of detection (LOD).

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Published date: 20 September 2008

Identifiers

Local EPrints ID: 147645
URI: http://eprints.soton.ac.uk/id/eprint/147645
ISSN: 0951-4198
PURE UUID: 351cd9b0-afc3-4131-89f3-424cb9c34b45
ORCID for G. John Langley: ORCID iD orcid.org/0000-0002-8323-7235

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Date deposited: 26 Apr 2010 09:25
Last modified: 26 Nov 2019 02:04

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Contributors

Author: Mohini A. Thite
Author: Robert Boughtflower
Author: Jeff Caldwell
Author: Laure Hitzel
Author: Clare Holyoak
Author: Stephen J. Lane
Author: Paul Oakley
Author: Frank S. Pullen
Author: Stefan Richardson
Author: G. John Langley ORCID iD

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