An X-ray fluorescence-confined spot technique has been developed and used for the determination of sulfur in compounds from air samples collected on small membrane filters and for lead and silicon in compounds from air samples collected on paper tape. On 100-mm2 spots, the minimum detectable limit for sulfur is 0.15μg, for lead and silicon it is 0.4μg. The technique is simple, precise, and rapid and should be applicable to the determination of elements above atomic number 12.