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Arrays of low‐temperature plasma probes for ambient ionization mass spectrometry
Author(s) -
Dalgleish Jon K.,
Wleklinski Michael,
Shelley Jacob T.,
Mulligan Christopher C.,
Ouyang Zheng,
Graham Cooks R.
Publication year - 2012
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.6435
Subject(s) - chemistry , dart ion source , mass spectrometry , derivatization , analyte , analytical chemistry (journal) , designer drug , chromatography , mephedrone , thermal ionization , chemical ionization , cathinone , ionization , ion , electron ionization , organic chemistry , psychology , drug , psychiatry , amphetamine , neuroscience , dopamine , biology
RATIONALE This paper reports the development of arrays of capillary‐based low‐temperature plasma (LTP) probes for direct sample analysis. These probe arrays allow a higher surface area to be analyzed, increasing the throughput in large sample analysis. Validation of these arrays was performed on illicit, cathinone‐based drugs marketed as 'bath salts'. METHODS LTP arrays consisting of 1, 7, and 19 probes were constructed with quartz capillaries and held together with silver epoxy resin adhesive. Three drugs, mephedrone, methylone and methylenedioxypyrovalerone, were analyzed with each plasma ion source and an ion trap mass spectrometer in full MS and in MS/MS positive ion mode. Chemical and thermal footprints were determined for each source. A reactive probe design was used to inject trifluoroacetic anhydride directly into the plasma stream for on‐line derivatization. RESULTS Small LTP probes and bundled arrays provide low picogram level limits of detection for mephedrone, methylone and methylenedioxypyrovalerone. Bundling the probes together in larger arrays increases the surface area analyzed by a factor of ten, while maintaining surface temperatures below 40 °C. Selectivity towards mephedrone and methylone was increased using trifluoracetylation under ambient ionization conditions. CONCLUSIONS Low‐temperature plasma ionization sources allow rapid detection of illicit 'bath salt' drugs in low amounts. The sources have a larger sampling area that allows faster detection of each analyte, and selectivity towards the selected drug is enhanced by adding reagents directly into the plasma stream. Copyright © 2012 John Wiley & Sons, Ltd.