Determination of carbofuran and diuron in FIA system using electrochemical sensor modified with organometallic complexes and graphene oxide

• FIA analysis is becoming the major technique in the field of automatic analysis.
• FIA has been used for analysis of wide variety of substances.
• Organometallic complexes are biomimetic catalysts of the P450 enzyme.
• Graphene oxide has large surface area, excellent conductivity and low cost.
• FIA is chemically clean, low cost, higher sensitivity and selectivity.

This paper describes the development of an electrochemical sensor coupled to flow injection analysis system for the detection of pesticides. The proposed sensor was prepared using a carbon paste electrode modified with hemin and nickel (II) 1,48,11,15,18,22,25-octabutoxy-29H, 31H-phthalocyanine complex as possible catalysts P450 enzyme and graphene oxide in order to improve the sensitivity of the sensor. In the first place, we used the cyclic voltammetry in a response range of −0.2 to 1 V to monitor the electrochemical response of each pesticide. In optimized conditions, an amperometric study of the proposed sensor was conducted applying the potential of 0.45 and 0.8 V for the redox reaction of carbofuran-phenol and diuron. The system showed a linear response in a concentration range between 5.0 × 10−6 and 1.4 × 10−4 and 5.0 × 10−5 and 1.0 × 10−3 mol L−1 and detection limit of 1.7 × 10−6 and 2.0 × 10−5 mol L−1 for carbofuran and diuron, respectively. The proposed sensor was applied in soil and carrot samples and the results obtained in the recovery study were close to 100%. The reliability of the proposed sensor was confirmed after comparing the results with those obtained in the comparative method (HPLC).