Quantitative analysis of a quaternary ammonium drug: ipratropium bromide by LC/ESI‐MSn in horse plasma and urine

A quantitative method, using LC/ESI-MSn with a quadrupole linear ion trap mass analyzer, has been developed for the analysis of ipratropium cation in horse plasma and urine. The method applies solid-phase extraction with WCX cartridges for plasma and MM2 cartridges for urine, prior to analysis by LC/ESI-MSn. The efficiency of extraction combined with the sensitivity and the selectivity of MSn allows for the quantification of ipratropium cation at picogram per milliliter levels. The analytical capabilities of the method have been successfully checked by the quantitative analysis of ipratropium cation in post-administration samples collected from horses treated by nebulization. Copyright © 2011 John Wiley & Sons, Ltd.