Delayed Sample Introduction System for Ion Mobility Spectrometry

Ion mobility spectrometry (IMS) is one of the most sensitive instrumental analysistechniques, which is extensively used for detection of drugs and explosives. It works basedon measuring the speed of ionized sample in atmospheric pressure under weak electric field.IMS is also used in laboratory for qualitative and quantitative analysis [1]. In this technique,sample must be transformed into the gas phase in order to be ionized [2]. There are severalmethods for introducing sample into IMS. Typical sample introduction system usuallyincludes a hot chamber, receiving the sample as solid, liquid or gas that is then transportedinto the ionization region by the carrier gas. Since the carrier gas is continuously running, thesample vapor flows from the beginning of the injection into the IMS cell, and would continueuntil the vapor is finished. The problem associated with the conventional method for solidsample introduction is that the injection port is continuously washed out by the carrier gas, sothe evaporated sample is diluted. Hence, it is gradually dispersed during the heating anddesorbing process. Consequently the signal becomes weak and spread over time. This is alsothe case for the solutions. Here we introduce a novel technique to overcome the problemsassociated with the conventional sample introduction systems for IMS.