RANGE OF DETECTION: 20 ppb to 1 ppm
Chlorothalonil RaPID AssayÒ Kit and Sample Diluent Reagents: acetone (pesticide grade), sodium chloride. Equipment: 250 mL polypropylene bottles, 15 mL polypropylene tubes, 13 x 100 mm glass test tubes, 50 mL precision pipet, 5 mL serological pipet, vortex mixer, scale or balance.
The concentration of non-systemic pesticides applied to crops may vary significantly across the surface of the crop resulting in 'hot' and 'cold' spots. For this reason, a sufficiently large sample of the celery should be pre-processed (chopped by hand or in a food processor) in order to obtain a representative homogeneous sample for extraction.
Add 100 mL of acetone to 50 grams of chopped celery sample in a 250 mL polypropylene bottle. Shake by hand for 15 to 20 seconds. Allow the solids to settle for about five minutes. Transfer approximately 4 mL of the extract (upper layer) to a 15 mL polypropylene tube and add 1/4 teaspoon (or approx. 2.0 g) of sodium chloride. Cap the tube and vortex to mix thoroughly. Allow the aqueous and acetone phases to separate (about 5 minutes).
Transfer 50 mL of the acetone phase (top layer) to a glass test tube and add 4.95 mL of Chlorothalonil Sample Diluent with a serological pipet. Analyze the diluted extract as the 'sample' according to package insert of the RaPID Assay.