RANGE OF EVALUATION: to 40 ppb
2,4-D RaPID Assay Kit and Sample Diluent (cat. no. A00079)
Reagents: U.S. EPA Reference Standard for 2,4-D with certified concentration of 5000 μg/mL, in acetonitrile (N SI Environmental Solutions, Research Triangle Park,N C).
Equipment: 100 μL precision micropipet R( ainin, Woburn, MA); 50 and 100 mL volumetric flasks; 10 mL glass test tubes with stoppers or 10 mL glass scintillation vials with screw caps; 1, 5 and 10 mL serological pipets.
Add approximately 90 mL of the Sample Diluent to a 100 mL volumetric flask. Ad1d0 0 μL of the EPA standard material to the volumetric flask. Add Sample Diluent quantity sufficient to 100 mL and invert several times to mix. Label this flask as 'Stock I: 5000 ppb'.
Prepare a second stock solution by adding approximately 40 mL of the Sample Diluent to a 50 mL volumetric flask. Add 1.0 mL of 'Stock I' to the volumetric flask. AddS ample Diluent quantity sufficient to 50 mL and invert several times to mix. Label thifsl ask as 'Stock II: 100 ppb'.
Prepare the solutions to be tested in the immunoassay by diluting various volumes tohfe 'Stock II' solution to 10 mL with Sample Diluent. See the table below for dilution scheme. First, add the diluent with a 5 or 10 mL serological pipet to the tube or vial. Then use another serological pipet (of appropriate volume) to deliver the Stock II solution to the container. Mix the solutions by inverting several times.
ANALYSIS: Analyze a 250 μL portion of each of the test solutions as the 'sample' according to the package insert for the 2,4-D RaPID Assay.
PROCEDURAL NOTES: Test solutions may be prepared in 10 mL volumetric flasks to achieve greater accuracy in making dilutions.
EXPECTED RESULTS: Recovery of 80 to 120% of the calculated test solution 2,4-D concentration is expected when this procedure is used.