Aza heterocyclic hydrocarbons (AHHs) present in urban atmospheric particulate matter have been analyzed by high-performance liquid chromatography (HPPLC) coupled with on-line fluorescence detection after a preseparation of the AHH fraction by one-dimensional dual-band thin-layer chromatography. Efficient preseparation and a significant increase in sensitivity over other methods were achieved. The HPLC fraction was identified by comparison of retention times and fluorescence emission spectra of individual components with data for authentic samples and also by the method of standard addition. These techniques were applied to the organic material present in the atmospheric particulate matter collected in the Tokyo metropolis. The concentrations (..mu..g/g of particulates (ng/m/sup 3/)) of identified AHHs (4-azafluorene, acridine, benz(a)acridine, dibenz(a,h)acridine, dibenz(a,j)acridine, dibenz(a,c)acridine, and 10-azabenzo(a)pyrene) were at the levels of 3 x 10/sup -2/ to 3.5 (3 x 10/sup -3/ to 3 x 10/sup -1/), and these were about 10-1000 times lower than those of major polycyclic aromatic hydrocarbons. Moreover, the concentrations generally decreased with increasing ring number.