Extraction of light filth from whole peppermint leaves: collaborative study

Results are reported for a collaborative study of a method for the extraction of light filth from whole peppermint leaves. A 5 g sample is defatted with isopropanol in a simple reflux appartus. Rat hairs, insect fragments, and whole insects are isolated by wet sieving on a No. 230 sieve, a deaerating boil in 40% isopropanol solution, flotation with Tween 80-Na4EDTA (1 + 1) and mineral oil-heptane (85 + 15), and trappings in a Wildman trap flask. Average recoveries obtained by 6 collaborators for 3 spike levels of rat hairs (5, 10, 15) were 83.3, 87.5, and 82.2%, respectively. For whole insects (5, 10, 15) recoveries averaged 85.0, 80.0 and 77.2% respectively; for insect fragments (20, 30, 50) recoveries averaged 79.6, 88.3, and 84.8%, respectively. The average recoveries for the 3 levels of each analyte were not significantly different. The method has been adopted official first action.