Microchip electrophoresis‐single wall carbon nanotube press‐transferred electrodes for fast and reliable electrochemical sensing of melatonin and its precursors

In the current work, single‐wall carbon nanotube press‐transferred electrodes (SW‐PTEs) were used for detection of melatonin (MT) and its precursors tryptophan (Trp) and serotonin (5‐HT) on microchip electrophoresis (ME). SW‐PTEs were simply fabricated by press transferring a filtered dispersion of single‐wall carbon nanotubes on a nonconductive PMMA substrate, where single‐wall carbon nanotubes act as exclusive transducers. The coupling of ME–SW‐PTEs allowed the fast detection of MT, Trp, and 5‐HT in less than 150 s with excellent analytical features. It exhibited an impressive antifouling performance with RSD values of ≤2 and ≤4% for migration times and peak heights, respectively ( n = 12). In addition, sample analysis was also investigated by analysis of 5‐HT, MT, and Trp in commercial samples obtaining excellent quantitative and reproducible recoveries with values of 96.2 ± 1.8%, 101.3 ± 0.2%, and 95.6 ± 1.2% for 5‐HT, MT, and Trp, respectively. The current novel application reveals the analytical power of the press‐transfer technology where the fast and reliable determination of MT and its precursors were performed directly on the nanoscale carbon nanotube detectors without the help of any other electrochemical transducer.