Use Of A Ccd-Based Imaging Detector And Capillary Sampling Techniques For Environmental Testing

A microformat ELISA has been developed for the simultaneous determination of multiple 2,4-dichlorophenoxyacetic acid (2,4-D) samples using a CCD-camera and highly efficient chemiluminescent enzyme substrates. The linear range was 4.5x10(-10)-4.5x10(-7) M with a lower detection limit of 4.3x10(-10) M, corresponding to 96 pg/ml or 192 pg/well with a CV of 12.5%. The use of gold coated silicon wafers and glass capillaries as solid phase supports in the imaging ELISA is also described. The highly reflective gold surfaces improved the linear range and the sensitivity as compared to thick-film patterned surfaces, Sampling in capillary tubes reduces the sensitivity and the linear range, but there are indications that the capillaries can act as light guides and thereby improve the light collection efficiency.