An electrochemical impedimetric immunosensor for ultrasensitive determination of ketamine hydrochloride

In this paper, an immunosensor for ultrasensitive and specific detection of ketamine is reported with electrochemical impedance as read-out signal. It is constructed based on the self-assembly modification (SAM) of 3-mercaptopropionic acid on Au electrode, the activation strategy by 1-ethyl-3-(3-dimethylaminoprophyl) carbodiimide (EDC)/n-hydroxysulfsuccinimide (NHS) and the immobilization of ketamine antibody to form the sensing surface. The antibody acts as the sensing host due to its specific covalent bonding with ketamine. The technique of electrochemical impedance spectroscopy (EIS) is employed to read-out the sensing signal. The value of electron transfer resistance (Ret) responds to the concentration of ketamine with a detection limit of 0.41 pmol/L. The immunosensor can be regenerated for more than 5 times resorted to elution by NaOH–H3PO4 (pH 12.0). When it was applied to detect the ketamine in spiked serum samples after 2000-folds dilution, there were satisfactory recoveries from 89.0% to 136.4% and tolerable interference from blood components. The so-prepared sensor is proven as a dominant element than those once reported ones in terms of the sensitivity and simplicity.