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1334360 
Technical Report 
Decomposition of Dioctyl Phthalate (DOP) 
Frund ZN Jr; Thompson, RE 
1995 
NIOSH/00233872 
13 
4 
6-15 
The effects of prolonged heating on dioctyl-phthalate (117817) (DOP) were investigated to quantify changes in purity, structure, and aerosol particle size distribution. Samples of fresh DOP (purity 99.11%) were heated at 167 degrees-C for 336 hours (hr) in a hot smoke ATI Q127 DOP penetrometer interfaced to an ATEC model 303 dilution unit of a model LAS-X Particle Measuring Systems laser/aerosol spectrometer. Heating at 167 degrees typically volatilized sufficient DOP to produce an air stream concentration of 100 micrograms per liter. Fresh DOP showed only traces of impurities, indicated by mass spectrometry, that corresponded to a 2-ethylhexylbenzoic-acid ester and 2-ethylhexanol. Prolonged heating caused very little decomposition, although the DOP changed to a brownish color. The estimated purity was 98.4%. Trace amounts of two impurities were detected. One was identified as phthalic-anhydride (85449) and the other as a long chain hydrocarbon. Approximately 0.51% of the impurities in heated DOP were due to 2-ethylhexanol. The geometric mean diameters of the particles generated from fresh and heated DOP were 0.224 and 0.244 micrometer (micron), respectively. Approximately 44% of the aerosol particles generated from fresh DOP samples and 53% of those from heated samples had particle sizes of 0.26 to 0.34micron. The authors conclude that DOP undergoes very little decomposition after prolonged heating. 
DCN-234296; Phthalates; Thermal decomposition; Laboratory testing; Chemical structure; Decomposition products; Aerosol particles; Chemical analysis; Oil mists