Particle analysis is useful for determining chemical compositions in a wide range of disciplines, from ascertaining the source of a petroleum sample to duplicating a fragrance. The technique is appealing to a broad cross-section of analytical sciences, but its applications are limited because, for existing equipment, sample size is limited, and testing is carried out under a high vacuum.
A real-time particle analyzer was developed that overcomes these limitations. In addition to identifying the elemental composition of a compound, it can determine the ratios of isotopes for each element within a sample. The system features a scaled-up laser and containment system for processing larger particles, and transports the atomized samples in a low-pressure stream of inert gas rather than in a vacuum. The inert gas provides a medium in which the sample retains a homogeneous mixture that is representative of the original particle's composition. The gas also supports multiple analyses, thus providing enough information to discriminate between isotopes as well as elements.
The particle analyzer includes a laser ablation chamber, a gas-filled conduit, and a mass spectrometer. An aerosol particle supply system that can employ, for example, an aerodynamic lens system, supplies aerosol particles into the laser ablation chamber. The laser ablation chamber can be operated at a low pressure, from 0.1 mTorr to 30 mTorr. The gas-filled conduit reduces the electrical charge distribution and the speed of ablated particles as the ablated particles collide with buffer gases in the gas-filled conduit.
The analyzer is self-contained and portable, so it can carry out analyses in the field. Its unique features make it particularly useful wherever screening is done for chemical and nuclear hazards, including environmental monitoring, first response to emergencies, and homeland security.