columnless gc/ims (ii) - B & S Analytik GmbH

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IJIMS 5(2002)2,160-174, p. 165M8A2000 Teflon was greater than 2 layers of S&S filter paper, Figure 14e shows thatthe retention times of both chemicals were shorter and the peak shapes were sharperthan those in Figure 14d. This again indicates that the chromatographic effect was themain factor contributing to their separation when extra layer(s) of material were addedover the sample filter paper.CONCLUSIONSThe improvement in peak detection quality during Ionscan analysis either bytemperature ramping in the desorber region or by the chromatographic effect has beendemonstrated with three examples encompassing chemicals with different polarities.Temperature ramping in the desorber region and the chromatographic effect wereachieved by adding extra layer(s) of material under or over the sample filter paper,respectively. These methods were fast and simple to apply without any hardware orsoftware modification to the existing Ionscan. The only change was to extend thedesorption time to 15 or 20 seconds in order to collect data for high molecular weightcompounds with long retention times such as cocaine and heroin. Modification to thelayer materials such as deactivation of the surface of the material or by changing thesurface of materials by applying coating chemicals will be studied in the future todetermine their effect on the separation of chemicals with similar polarity.REFERENCES1. Su, C., Rigdon, S., Babcock, K., Noble, T., and deFur, P., “Columnless GC/IMS (I)– A Study of The Variation in The Thermal Desorption Profiles of Three Models ofIonscan IMS Instrument.” Proceedings of Eighth Int. Conference on Ion MobilitySpectrometry, Buxton, UK, August 1999, in press.2. The Merck Index, Ninth Edition, Merck & Co., Inc., Rahway, NJ, 1976.
IJIMS 5(2002)2,160-174, p. 166Table 1. Average Retention Time and Standard Deviation of Five ReplicateAnalyses of Methamphetamine, Cocaine and Heroin with DifferentMaterials Added Under the Sample Filter PaperLayer(s) ofMaterialThickness( µm )Methamphetamine Cocaine Heroin( sec ) ( sec ) ( sec )No S&S paper 0.0 1.9 ± 0.2 2.7 ± 0.2 3.7 ± 0.41 S&S paper 0.2 3.0 ± 0.2 4.3 ± 0.2 5.4 ± 0.32 S&S papers 0.4 3.5 ± 0.4 5.8 ± 0.2 7.5 ± 0.63 S&S papers 0.6 5.1 ± 0.5 7.9 ± 0.5 10.2 ± 0.51 M8A2000 Teflon pad 0.6 4.3 ± 0.4 6.7 ± 0.2 9.9 ± 0.51 Cellulose pad 0.8 5.8 ± 0.6 9.5 ± 0.5 12.9 ± 0.4Table 2. Average Retention Time and Standard Deviation of Five ReplicateAnalyses of Methamphetamine, Cocaine and Heroin with DifferentMaterials Added Over the Sample Filter PaperLayer(s) ofMaterialThickness( µm )Methamphetamine Cocaine Heroin( sec )( sec ) ( sec )No S&S paper 0.0 1.9 ± 0.2 2.7 ± 0.2 3.7 ± 0.41 S&S paper 0.2 3.5 ± 0.5 6.1 ± 0.5 8.1 ± 0.72 S&S papers 0.4 5.8 ± 1.2 10.2 ± 0.9 13.7 ± 0.83 S&S papers 0.6 9.9 ± 1.4 15.6 ± 0.8 20.5 ± 0.81 M8A2000 Teflon Pad 0.6 2.3 ± 0.5 4.2 ± 0.2 6.3 ± 0.21 Cellulose pad 0.8 14.1 ± 0.7 18.7 ± 0.5 22.8 ± 0.7
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