A SIMPLE ASSAY FOR 2,4-DICHLOROPHENOXYACETIC ACID USING COATED TEST-STRIPS

ABSTRACT

Immunoassay test strips utilizing ascending chromatography have been devised for the detection of 2,4-dichlorophenoxyacetic acid (2,4-D). This test is inexpensive, requires no instrumentation, and relies on the application of antibodies to 2,4-D adsorbed onto colloidal gold particles. The assay, although not completely optimized is capable of detecting 0.02 µg/mL. The format for this assay involves addition of the unknown sample to a small test tube that contains 0.25 mL buffer and anti-2,4-D colloidal gold conjugate followed by addition of the test strip. The anti-2,4-D gold conjugate co-migrates with the sample past pre-adsorbed bovine albumin labeled with 2,4-D (BSA-2,4-D). If 2,4-D is present in the unknown sample at concentrations above the threshold value, then the colloidal gold-labeled anti-2,4-D antibody will not bind to the BSA-2,4-D adsorbed to the nitrocellulose strip but will continue to migrate toward the top of the strip. To determine the presence of the analyte, the colloidal gold labeled antibody that binds to the BSA-2,4-D zone (as determined by a visible purple band) is compared to positive (containing concentrations of 2,4-D above 0.02 µg/mL) and negative controls (containing no analyte).

Keywords:

• Immunoassay test strips
• Lateral flow immunoassay
• 2,4-D
• Environmental monitoring

Acknowledgments