AOAC Official Method 974.33 Filth in Green Leafy Vegetables
First Action 1974
A. Light Filth
(Applicable to whole or chopped kale, turnip, mustard, and collard greens.)
(a) Canned (First Action 1979; Final Action 1988).—Drain can contents on No. 8 sieve 2 min and reserve brine. Immediately take
100 g from sieve. If pieces are 1 cm in length, place in 2 L trap flask. Cut larger pieces on small cutting board to this size to avoid interference
with magnetic stirring. Wash residue from cutting into trap flask with 40% isopropanol. Add 40% isopropanol to fill trap flask to 1 L mark. Add magnetic stirring bar (13 ´ 76 mm). Add 50 mL light mineral oil, 945.75C(p) (see 16.1.01). Place flask on magnetic stirrer, 970.66B(c) (see 16.1.02). Slowly bring stirrer to maximum speed at which stirring bar is just visible at bottom of vortex, avoiding visible or audible splashing. Proper stirring will produce vertical rolling of contents. Stir 5 min, remove flask from stirrer, and let stand 1 min. Add 40% isopropanol down rod to fill flask. Manually stir material in bottom of flask with rotary motion ca 15 s. Repeat stirring at two 5 min intervals. Raise stirring rod from bottom of flask and clamp. Let stand additional 10 min and trap off into beaker. Repeat trapping with 35 mL oil, stirring manually 1 min. Filter onto ruled papers.
