Analysis of peroxyacetyl nitrate (PAN), peroxypropionyl nitrate, peroxy-rt-butyryl nitrate, and peroxyisobutyryl nitrate (PiBN) with a non-polar capillary column indicated PAN not to coelute with PiBN. Isopropyl nitrate coeluted with PAN, n-butyl nitrate with PiBN and ethyl nitrate with chloroform, at oven temperature 30 degreesC. In addition methyl nitrate, n-propyl nitrate, 2-butyl nitrate, 2-methyl-2-butyl nitrate, 3-pentyl nitrate and 2-pentyl nitrate were studied. Their response factors in the electron-capture detector were also determined. Tetrachloroethylene, carbon tetrachloride and chloroform whose vapors occur in the atmosphere were also examined. (C) 2001 Elsevier Science B.V. All rights reserved.