Pesticide Analytical Manual Vol. I SECTION 401 E1 EXTRACTION WITH METHANOL Reference Krause, RT(1980)/ Assoc. Off. Anal. Chem. 63, 1114-1124 Principles Residues are extracted from high moisture products (>75% water)with methanol found to be the most effective extractant for N-methylcarbamates in tests using radiolabeled materials. The filtered extract is concentrated with a system that permits evaporation of the relatively high boiling point methanol without destroying heat e residues pparatus Buchner funnel(Buchner), porcelain, 12 cm diameter waporator, vacuum rotary with circulating chilled liquid (see Figure 401-b intain 1+I water/ethylene glycol solution in condensing coils and around receiving flask at -15C with 1/2 horsepower cooling unit. Insulate con- denser with Styrofoam or other material Control evaporator vacuum with vacuum pump and gauge; manometer may be used but is not preferred filter paper, Sharkskin, or 597 S&s to fit Buchner Figure401七 flask, round-bottom (r-b), 2 L, 5 Vacuum Rotary Evaporator homogenizer, Polytron Model T 10-35, with PT 35K genera tor containing knives, head equipped with metal (not Teflon)bushing homogenizer jar, four-side glass, I qt magnetic stirrer, star, 10 mm di ameter×8 mm height vacuum filtration flask. 500 mL Reagents bath]circulator methanol, distilled from all-glass To remove higher boiling solvents from solutions apparatus containing heat-labile residues. Water/ethylene Directions glycol at -15C cools receiving flask of rotary evaporator and (insulated] evaporator con- Add 150 g chopped high mois- denser ture product and 300 mL methanol to homogenizerjar Homogenize mixture 30 sec at about half speed(setting of 7)and then 60 sec at full speed Vacuum filter homogenate through Buchner fitted with filter paper and collect filtrate in 500 mL vacuum filtration flask. Reduce vacuum during filtration if filtrate begins to boil Transfer portion of filtrate equivalent to 100 g sample to 2 L r-b flaskTransmittal No. 94-1 (1/94) Form FDA 2905a (6/92) 401–3 Pesticide Analytical Manual Vol. I SECTION 401 E1 EXTRACTION WITH METHANOL Reference Krause, R.T. (1980) J. Assoc. Off. Anal. Chem. 63, 1114-1124 Principles Residues are extracted from high moisture products (>75% water) with methanol, found to be the most effective extractant for N-methylcarbamates in tests using radiolabeled materials. The filtered extract is concentrated with a system that permits evaporation of the relatively high boiling point methanol without destroying heat￾labile residues. Apparatus Buchner funnel (Buchner), porcelain, 12 cm diameter evaporator, vacuum rotary with circulating chilled liquid (see Figure 401-b). Maintain 1+1 water/ethylene glycol solution in condensing coils and around receiving flask at –15° C with 1/2 horsepower cooling unit. Insulate con￾denser with Styrofoam or other material. Control evaporator vacuum with vacuum pump and gauge; manometer may be used but is not preferred. filter paper, Sharkskin, or 597 S&S, to fit Buchner flask, round-bottom (r-b), 2 L, Ts 24/40 homogenizer, Polytron Model PT 10-35, with PT 35K genera￾tor containing knives, head equipped with metal (not Teflon) bushing homogenizer jar, four-side, glass, 1 qt magnetic stirrer, star, 10 mm di￾ameter × 8 mm height vacuum filtration flask, 500 mL Reagents methanol, distilled from all-glass apparatus Directions • Add 150 g chopped high mois￾ture product and 300 mL methanol to homogenizer jar. • Homogenize mixture 30 sec at about half speed (setting of 7) and then 60 sec at full speed. • Vacuum filter homogenate through Buchner fitted with filter paper and collect filtrate in 500 mL vacuum filtration flask. Reduce vacuum during filtration if filtrate begins to boil. • Transfer portion of filtrate equivalent to 100 g sample to 2 L r-b flask. Figure 401-b Vacuum Rotary Evaporator To remove higher boiling solvents from solutions containing heat-labile residues. Water/ethylene glycol at –15° C cools receiving flask of rotary evaporator and (insulated) evaporator con￾denser. Condenser (insulated) Motor Cooling unit Water bath 35° C Constant temperature bath circulator -15° C Needle valve Pump Manometer To vacuum pump