IMMUNODETECTION OF HERBICIDE 2,4-DICHLOROPHENOXYACETIC ACID BY FIELD-EFFECT TRANSISTOR-BASED BIOSENSORS

An immunosensor method for determination of herbicide 2,4 dichlorophenoxyacetic acid (2,4-D) was developed. It is based on the use of the competition between 2,4-D in analyzed probes and 2,4-D-peroxidase conjugate for binding with antibodies being immobilized on porous photo-activated cellulose membranes. These membranes were attached to the gate region of pH-sensitive field transistor (FET) and electrochemical detection of enzyme activity was carried out. Mixture of ascorbic acid (0.1 mM), o- phenylenediamine (1.0 mM), hydrogen peroxide (1.0 mM) was used as substrate solution. The initial rate of pH shift of the FETs gate region was recorded as measured parameter. The developed system permits to determine 2,4-D in water solutions for concentrations down to 1 ng/ml. This portable and inexpensive immunosensor meets modem requirements as analytical system for ecological monitoring.