Ion Mobility Spectrometry in Carbon Dioxide

Heating rates of 20-30 "C gave satisfactory results for several additives, but no effort was made to establish an optimum heating rate. Extraction of polypropylene pellets with acetonitrile a t room temperature overnight gave clear evidence for the additives, but the extraction was approximately 2% efficient. Extraction with boiling decalin (4, 5) gave 0.053 wt 70 UV-531 in this sample. The samples used in this work, 1-2 mg, do not constitute either upper or lower limits on the amounts of polymer that can be used. Smaller samples allow one to study the distribution of additives within a bulk sample. This use of small samples (I1 mg) allows determination of heterogeneities of additive concentrations in bulk samples but would not produce a good average value of additive concentration in a large batch of polymer. Care must be maintained in these studies that the bulk of the decomposition products of polypropylene do not contaminate the metal surfaces in the acceleration region of the mass spectrometer.