MATRIX: Corn Oil
RANGE OF DETECTION: 10 to 500 ppb
MATERIALS: Atrazine RaPID Assay, Kit and Sample Diluent. Reagents: acetonitrile (pesticide grade). Equipment: 15 mL polypropylene tubes with screw caps, 15 mL polypropylene centrifuge tubes, serological pipets, test tube rack and pan balance.
EXTRACTION PROCEDURE: Weigh 5 g of corn oil into a 15 mL polypropylene tube. Using a serological pipet add 5 mL of acetonitrile, cover with screw cap and shake for 30 seconds. Place the tube in a rack and allow the oil and acetonitrile phases to separate (approximately two minutes). Transfer 4 mL of the acetonitrile (upper) layer to a clean centrifuge tube using a serological pipet. Extract the oil layer again by adding another 5 mL of acetonitrile to it. Follow the procedure above. Transfer 4 mL of the acetonitrile layer to the test tube containing the first 4 mL that was removed. Mix the 8 mL of acetonitrile extract thoroughly. The extract should be free of any dispersed oil. Any oil present can be removed from the acetonitrile extract by centrifugation at 1000 x g for five minutes. The oil will be on the bottom.
ANALYSIS: Dilute the acetonitrile extract 1:50 in Atrazine Sample Diluent using serological pipets (e.g. 0.1 mL extract plus 4.9 mL Sample Diluent). Analyze the diluted extract as the 'sample' according to the package insert for the Atrazine RaPID Assay.