Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/13/2009
Publication Date: N/A
Interpretive Summary: N/A
Technical Abstract: Differential mobility spectrometry (DMS), also commonly referred to as high-field asymmetric waveform ion mobility spectrometry (FAIMS), is a rapidly advancing technology for gas-phase separation. DMS has the potential to emerge as a major stand-alone separation technique such as LC or GC. To date, several applications of DMS have been made for a wide variety of matrices such as explosives, warfare agents and pesticides. Among its main advantages over traditional instrumentation techniques are that is significantly faster, simple, and inexpensive. DMS is readily miniaturized, making it ideal as a rapid analytical screening technique for in field detection of insecticides. A novel method based on DMS technology has been developed and evaluated for the detection of insecticides. Evaluation of DMS parameters such as carrier gas flow rate and composition, dispersion voltage and sensor temperature will be discussed in this presentation. Methods (95/120) Sample working solutions were prepared in either pure acetone, acetonitrile or methanol at concentrations ranging from 1 to 10 ng/µL. Experiments were completed using two Sionex MicroDMx analyzers. One that was attached as a detector to a Finnigan GC and used for measurements of field dependence of mobility, for quantitative characterization of response, and for studies with modifications of the drift gas. The second analyzer was coupled in front of a mass spectrometer, so the core ions in DMS spectra could be mass identified. In both instruments, the analytical parameters and components were identical and included a width of 0.5 mm between the electrodes (4 x 15 mm) and a 3 mCi 63Ni ion source. Preliminary Data (190/300) The sensitivity of a DMS system is greatly affected by parameters such as carrier gas composition and moisture level, and inner and outer electrode cell temperatures. For this reason, these parameters were evaluated to optimize the transmission of ions throughout the DMS analyzer. Initial studies of differential mobility spectra for negative ions from organophosphates insecticides in pure N2 showed compensation voltages from -1 to -24 V with a separation voltage (field) of 1200 V (24 kV/cm). Less fragmentation was observed at lower electric fields. Preliminary studies also showed that increasing the drift gas flow rate increased the transmission of ions to the detector, but decreased the resolution. The optimization of the different parameters that affect the sensitivity and resolution of a DMS-based method is evaluated and discussed in this presentation.