1.3.2 Sulfur Dioxide. The collection efficiency of SO2 in 3^ H2O2 solution as absorber in two impingers connected in series has been determined (8). With 15 mL peroxide solution contained in each midget impinger, collection efficiency was found to be 96%. Over the temperature and concentration range examined, no change in the collection efficiency was observed. Collection efficiency dropped to 90% at a sampling rate of 3 L/min. When using much higher sampling rates, e.g. 12 L/min, in conjunction with a 47 mm diameter silica-fiber, and two 250 mL capacity impingers in series, each containing 150 mL of 3% H2O2, a collection efficiency 98% of SO2 was obtained (9).