A simple closed-vessel nitric acid digestion method for a polyethylene/polypropylene polymer blend

A simple, high pressure asher digestion method was developed for a polyethy lene/polypropylene polymer blend. A 0.15-g sample has been digested in 2.5 mL nitric acid in a quartz closed vessel under high pressure and high tempe rature. The digestate was then filtered and analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES). Twenty-three elements were determined in the sample. Detection limits were in the low parts-per-billi on range, and precision was better than 5% relative standard deviation for most metals. The accuracy of the method was determined by performing spike recoveries for 11 test elements. Recoveries were in the 90-100% range for a ll elements. The digestion technique eliminated the need for the harsh acid mixtures (including H2SO4 + HNO3 and H2O2) that are routinely used for pol ymer samples.