the present invention provides methods and apparatus for analyzing the particulate contents of a sample such that a high proportion of the sample particles are analyzed without discrimination against high electronegativity and high ionization potential elements . in an exemplary embodiment , the invention comprises an apparatus for analyzing the particulate content of a sample having particulate diameters in the range of 0 . 001 - 10 microns . the apparatus comprises an evacuable chamber equipped with a chamber entrance through which a particle - laden gas stream enters . an inlet device , such as a capillary , communicates with the chamber entrance for inputting the particle - laden gas stream to the evacuable chamber . a laser is positioned to produce a focused laser beam which intersect the particle - laden gas stream at position approximately 0 . 1 mm from the chamber entrance . the laser beam has a power density sufficient to fragment and ionize particles entrained within the particle - laden gas stream . a detector is positioned to detect the ionized species produced by the laser . the laser beam is focused so that the beam has a cross - sectional area in the plane of intersection between the particle - laden gas stream and the laser beam that is at least as large as the cross - sectional area of the particle - laden gas stream in the plane of intersection . in one embodiment , the lens is a set of two cylindrical lenses .