Chitosan-metal Composite Modified Electrodes: Preparation And Their Application In Electrochemical Detection Of Hydrogen Peroxide

Chitosan is prepared by the deacetylation of chitin and possesses free amines and hydroxyl groups which are available for chelating metallic ions and adsorpting organic molecules or biomolecules, so chitosan are widely used in the fields of food industry, medicine, agriculture and materials science. Because of its good adorption and film-forming abilities, the study on sensors based on chitosan-modified electrodes is hot research topic. However, the fact that chitosan shows poor solubility in neutral or basic aqueous media limits its application. In this work, O-carboxymethyl chitosan (O-CMC) was synthesized to improve its solubility, and three kinds of new chitosan-metal composite modified electrodes were designed and prepared. The resulting electrodes were used in electrochemical sensors to detect H2O2. The major work and results are outlined as follows:(1) O-carboxymethyl chitosan (O-CMC) was synthesized by the reaction of chitosan and monochloroacetic acid. O-CMC was then deposited onto the surface of glassy carbon electrode by Chronoamperommetry. Subsequently, Cu2+ was adsorpted into the chitosan film on the surface of electrode and further reduced to Cu nanoparticels to obtain the carboxymethyl chitosan/Cu composite modified electrode. H2O2 was detected by the sensor based on the modified electrode. The detection results show a linear response to H2O2 concentration range from 1 to 10000μmol/L with a related coefficient of 0.9997. The sensitivity is 33μA·L·mmol-1·cm-2 and the detection limit is 1μmol/L.(2) The carboxymethyl chitosan/Ag composite modified electrode was prepared by using the same method as mentioned above. H2O2 was detected by the sensor based on the modified electrode. The detection results show a linear response to H2O2 concentration range from 10 to 6000μmol/L with a related coefficient of 0.9999. The sensitivity is 37μA·L·mmol-1·cm-2 and the detection limit is 1 nmol/L.(3) Aniline and chitosan solution was mixed with diluted hydrochloric acid in an electrochemical cell and the mixture was ultrasonically agitated for minutes. The chitosan/polyaniline composite film was electrochemically deposited onto the surface of glassy carbon electrode at a potential of 0.9 V for 200 seconds. The chitosan/polyaniline/Pd composite modified electrode was prepared by using the same method as mentioned above. H2O2 was detected by the sensor based on the modified electrode. The detection results show a linear response to H2O2 concentration range from 10 to 7000μmol/L with a related coefficient was 0.9998. The sensitivity is 46μA·L·mmol-1·cm-2 and the detection limit is 1μmol/L.All the sensors for H2O2 detection exhibite fast response, good repeatability and long-term stability.