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Evaluation of the sensitivity of miniaturized liquid chromatography‐electrospray ionization‐mass spectrometry for pharmaceutical analysis
Author(s) -
Kranendijk Martijn,
Waterval Joop C. M.,
Somsen Govert W.,
de Jong Gerhardus J.
Publication year - 2005
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/jssc.200500203
Subject(s) - chromatography , chemistry , mass spectrometry , volumetric flow rate , electrospray ionization , electrospray , analytical chemistry (journal) , physics , quantum mechanics
LC‐ESI‐MS is applied frequently in pharmaceutical analysis. The sample amount is generally not restricted, however with LC‐ESI‐MS, a lack of sensitivity may still be observed with standard‐bore LC columns in isocratic mode. Therefore, it was investigated whether increased sensitivity could be achieved by using miniaturized LC‐ESI‐MS. Seven columns ranging from 0.1 to 4.6 mm ID were tested using several instrument setups. For proper comparison, a sensitivity gain factor (SGF) was introduced. The SGF expresses the extra sensitivity that may be obtained on top of the normal increase of peak concentration, which can be expected when the column ID is reduced. Desogestrel, mirtazapine, and sugammadex sodium were used as test compounds. For desogestrel and sugammadex sodium, the SGF increased up to a factor of 5–13 when the column ID was reduced, indicating enhanced ionization efficiencies at lower flow rates. Optimum sensitivity was found for the 0.3 mm column coupled in combination with a microinjection valve and a dedicated low flow rate interface. For mirtazapine, no increase of SGF was observed when the column ID was decreased. Apparently, the ionization efficiency of this compound is not affected by the flow rate and the spray quality.