1 research outputs found
Quantitative Response of IMS Detector for Mixtures Containing Two Active Components
This study describes the relationship between the output
signal
of the ion mobility spectrometry (IMS) detector and the concentrations
of two compounds being simultaneously introduced into the reaction
section. Investigations were performed for three pairs of compounds,
that is, dimethyl methylphosphonate (DMMP) and acetone, methyl <i>tert</i>-butyl ether (MTBE), and acetone, as well as trimethylamine
(TMA) and <i>n</i>-nonylamine (NA). Vapors of the investigated
compounds were produced in a two-channel generator with permeation
sources and a dilution system based on mass-flow controllers. The
generator design and the method of concentration determination are
discussed in this paper. It was found that admixture can differently
influence detection of an analyte. The presence of acetone does not
effect the signal corresponding to dimer ions of DMMP. For pairs MTBE
+ acetone and TMA + NA characteristic peaks of analyte ions diminish
with growing concentration of admixture, however, the detection based
on the peak of the asymmetric dimer containing proton-bound molecules
of both compounds is effective. For the detection of TMA in the presence
of NA, the signal generated by the asymmetric dimer ions is meaningfully
higher than the signals of monomer or dimer TMA ions measured without
the NA admixture. The course of calibration dependencies was analyzed
on the basis of a simple mathematical model of the reaction region.
This model provided an estimation of the intensity of the signal for
a given ionic species for definite concentration of analyte