Development Of Immunoassay For The Determination Of Atrazine

A direct competitive enzyme-linked immunosorbent assay (ELISA) and a colloidal gold-based immunochromatographic strip were developed to detect the herbicide atrazine.The hapten was synthesized successfully and conjugated to BSA, OVA and HRP to prepare immunogen, coating antigen and enzyme tracer with the active ester method, separately. New Zealand white rabbits were immunized and the polyclonal antibody was obtained from their serum with high specificity for atrazine.The ELISA had a half-maximum inhibition concentration (IC50) of0.12ng mL-1and a limit of detection (LOD, calculated as IC15value) of0.01ng mL-1. The cross-reactivity with propazine (96.53%), prometryn (76.57%) and ametryn (28.02%) were higher among eleven triazine herbicides and others were all lower than20%. The assay was used to detect four spiked water samples (purified, tap, well and Haihe River water), one spiked soil sample and one spiked corn sample. The recovery ranged from76.5%to108.1%. And the coefficients of variation of intra-and inter-assays ranged from3.2to8.2%, and5.2to9.6%, respectively. The spiked samples were analyzed by high performance liquid chromatography (HPLC) to further verify the accuracy of ELISA. The linear regression equation between the data obtained by the ELISA and HPLC was y=1.004x-0.049with a correlation coefficient (r2) of0.991. It indicated that the ELISA was both accurate and reliable for the on-site detection of atrazine in various samples. A large number of samples could be detected simultaneously.Meanwhile, an immunochromatographic strip assay using colloidal gold-labeled antibody was developed. The visual LOD (the minimum concentration producing a significant degressive color intensity compared with the control line) of the assay for atrazine was2ng mL-1and the results could be obtained within7-10min. Four kinds of spiked water samples were analyzed directly by the test strip without any pretreatment and the LOD for water sample was2ng mL-1. Meanwhile, soil and corm samples were analyzed after simple pretreatment and the LOD was40μg kg-1. The results obtained by the immunochromatographic strip correlated well with those determined by ELISA. Because of its high specificity, fast detection and low cost, the strip could serve as an on-site screening of atrazine in water, soil and corn samples.