A Miniature Mass Spectrometer (MMS) with an array detector has been developed at the Jet Propulsion Laboratory (JPL). The spectrometer has a focal plane geometry, and an array detector that can measure the intensities of different masses simultaneously after their separation along the focal plane. In the past, the large mass, size and the lack of an array detector with high gain (such as an electron multiplier) did not allow the application of focal plane mass spectrometer to the measurement that required high sensitivity and portability. In the JPL developed-MMS, miniaturization has been accomplished by using rare earth magnet material and novelties in the design of the magnetic and electric sectors. A new ion detector was developed for the measurement of the intensities of different mass ions. The array detector is based on the conversion sequence of ions into electrons into photons and their final measurement by a photon array detector. MMS possesses high sensitivity, specificity, and fast response time and can be used as a universal chemical analyzer. It will find application in a variety of Home Defense tasks. MMS is presently being applied for the detection of propellants (hydrazine and its derivatives). The instrument will have a mass of 1-2 kg and consume a power of 2-4 W for operation
A method for the chemical analysis of individual aerosol particles on a real-time basis has been developed. This is accomplished by measuring their mass spectra. In this method, particles are directly introduced in the ion source of the mass spectrograph in the form of a beam. Volatilization and ionization of a particle in an ion source of the mass spectrograph is performed by using a pulsed high-energy Nd-YAG laser. Each particle, when hit by the laser pulse, produces a burst of ions of different masses. These ions are spatially separated according to their masses along the focal plane of a mass spectrograph and their intensities are measured simultaneously by an array detector. Some of the preliminary results on the mass spectral measurement of potassium biphthalate particles are presented. Volatilization and ionization of particles eliminate any possible substrate sample matrix interferences in the analysis. In order to preserve the real-time feature of the method for the analysis of particles present in low concentrations, the aerosol sample is concentrated by using a two-stage virtual impactor.
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