Rapid detection of urushiol allergens of Toxicodendron genus using leaf spray mass spectrometry.

A new ambient ionization method--leaf-spray mass spectrometry--is used to detect allergenic urushiols directly from poison ivy (T. radicans) leaves with no sample preparation. These simple measurements show all the urushiols previously reported using liquid chromatography mass spectrometry methods. Tandem mass spectrometry analysis of the leaf spray ions confirms the identifications. Enhanced detection of some urushiols was achieved in the negative mode with the addition of chloride anions to the spray solvent.