ABSTRACT
This chapter discusses the use of ion mobility spectrometry (IMS) for the detection and analysis of vapor constituents released from marijuana before and during smoking. IMS is a technique based on ionizing the sample under atmospheric pressure conditions and recording the positive and negative ion mobility spectra of the product ions. The IMS technique offers a real-time approach to ultrasensitive detection of marijuana either as an ambient air monitor or as a detector providing an enhanced analytical capability to gas, supercritical, or liquid chromatography. The proton transfer reaction mechanism is implemented in IMS by using hydronium reactant ions which have a proton affinity of 723.8 kJ/mol. Two alternative ion-molecule reactions which have been developed for IMS involve the use of ammonia and acetone as reagent gases. Mass spectrometric studies have shown that a protonated dimer ion of acetone is easily formed under high pressure conditions such as in the reactor of an IMS.
