Volume 44, Issue 1 (January 1999)
The Analysis of Methamphetamine Hydrochloride by Thermal Desorption Ion Mobility Spectrometry and SIMPLISMA
Ion mobility spectrometry (IMS) has been successfully developed to yield an advanced portable instrument. Such instruments may detect trace quantities of regulated substances at the crime scene. The atmospheric ion chemistry that occurs within the instrument may hinder the determination of analytes in realworld samples. The use of temperature programming adds an extra dimension to the data that improves the selectivity of the IMS data when chemometric processing is applied. The SIMPLISMA (SIMPLe-to-use-Interactive Self-Modeling Mixture Analysis) method is demonstrated for modeling variances in IMS data that are introduced from the temperature program. Methamphetamine hydrochloride IMS peaks are obscured by chemical interferences that arise from cigarette smoke residue. Cigarette smoke residue is pervasive at crime scenes. The ability of SIMPLISMA to resolve the analyte peaks that correspond to methamphetamine hydrochloride from interfering cigarette smoke has been demonstrated. A reduced mobility of 1.62 cm2V−1s−1 was observed for a methamphetamine hydrochloride monomer. With the IMS drift tube at room temperature, a second peak was observed at 1.24 cm2V−1s−1, which is consistent with a dimer ion. This peak has not been previously reported.