MATRIX: Grain corn
ANALYTES: Atrazine, Alachlor, Cyanazine, and Metolachlor
RANGE OF DETECTION:
Atrazine: 20-1000 ppb
Alachlor: 20-1000 ppb
Cyanazine: 20-600 ppb
Metolachlor: 20-1000 ppb
RaPID Assay Kit and Sample Diluent Reagents: methanol (pesticide grade), distilled or deionized water.
Equipment: laboratory grinding mill or coffee grinder, 20-mesh sieve, serological pipets, 10 x 13 mm glass test tubes, test tube rack, 125 mL polypropylene widemouthed bottles with polypropylene screw closures, freezer (~0°C).
Apparatus: laboratory blender or mixer (Method A), water bath shaker (Method B).
SAMPLE PREPARATION: Grind the corn sample (>25 g) to a fine powder (i.e. to pass through a 20-mesh sieve).
Method A: (Homogenization) Add 20 g of the powder to 80 mL of 4:1 methanol/water (4 parts methanol plus 1 part water) in a blender jar. Blend for two minutes at high speed. Transfer the homogenate to a polypropylene sample bottle. Cap the bottle tightly and place in freezer overnight (~ 12 hours).
Method B: (Heating)
Add 20 g of the powder to 80 mL of 4:1 methanol/water (4 parts methanol plus 1 part water) in a polypropylene sample bottle. Hand tighten the cap and invert several times to mix. Loosen the cap slightly and position the sample upright in a shaker water bath at 65-70°C. Agitate the sample for 2 hours at 35 revolutions (oscillations) per minute. Remove the sample bottle from the water bath. Tighten the cap and allow the sample to sit at room temperature for one hour. Place sample in freezer overnight (ò 12 hours).
ANALYSIS: Remove the sample bottle from the freezer and invert the bottle several times to mix. Let the contents come to room temperature allowing the solids to settle. Dilute an aliquot of the supernatant 1:50 in a glass test tube with the appropriate Sample Diluent (provided in the RaPID Assay Kit) using serological pipets (e.g. 0.1 mL extract plus 4.9 mL diluent).
Analyze the diluted extract as the 'sample' according to the package insert for the RaPID Assay.