Electrochemical Determination of Neurotransmitters at Crown Ether Modified Carbon Nanotube Composite: Application for Sub‐nano‐sensing of Serotonin in Human Serum

We propose an electrochemical sensor based on applying two successive thin layers from a mixture of multiwalled carbon nanotubes‐ionic liquid crystal and crown ether at glassy carbon electrode surface (GC/(CNTs‐ILC)/Crown). The sensor was used for sensitive determination of neurotransmitters based on effective synergism between its components. The compact conducting surface of (CNTs‐ILC) with large surface area allowed the assembling of stable host‐guest inclusion complexes between crown ethers and neurotransmitters. The GC/(CNTs‐ILC)/Crown exhibited excellent electro‐catalytic activity toward the determination of serotonin (ST) in a wide linear dynamic range: 0.005 μmol L−1 to 100 μmol L−1. In the concentration range 0.005 μmol L−1 to 1 μmol L−1, the detection limit is 2.03×10−10 mol L−1 and quantification limit is 6.78×10−10 mol L−1 with correlation coefficient 0.999. The sensor was successfully applied for ST detection in human serum samples with satisfied recovery results. The sensor showed excellent analytical performance for the determination of ST in terms of low detection limit, good sensitivity and reproducibility. Furthermore excellent anti‐interference ability and simultaneous determination of ST in presence of other compounds as ascorbic acid, dopamine and antidepressant drug were achieved.