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From

Rapid and Sensitive Spectroelectrochemical Detection of Lidocainehydrochloride and Caffeine with Screen-Printed Electrodes

A. Habekost

World Journal of Chemical Education. 2016, 4(5), 107-113 doi:10.12691/wjce-4-5-3
  • Figure 1. Chemiluminescence spectrum of [Ru(bpy)3]2+ (100 μmol/L) with lidocainehydrochloride (10 μmol/L) as coreactant. The chemiluminescence spectrum was recorded as follows: Wavelength scan 450-700 nm; scan speed 300 nm / min; electrical excitation pulse from a pulse generator (width 0.1 s; frequency 0.5 s-1; pulse height 1-3.54 V)
  • Figure 2. Experimental setup. Top: From left to right: programmable pulse-generator (Power Cassy), data acquisition system (Sensor Cassy), photomultiplier tube with glass fiber above the SPE. Bottom: Part of photo above with clearly seen SPE and glass fiber
  • Figure 3. ECL-intensity as a function of the applied voltage. Red line: only [Ru(bpy)3]2+, black dashed line: [Ru(bpy)3]2+ + caffeine (1 mmol), black line: [Ru(bpy)3]2+ with lidocaine (1 mmol)
  • Figure 4. Cyclic voltammogram of [Ru(bpy)3]2+ (1 mmol) with lidocaine (1 mmol, red line) and without lidocaine (red, dashed line). ECL-intensity (black line). Scan rate: 50 mV/s
  • Figure 5. ECL-intensity as a function of the lidocaine concentration. Inset: expansion for low concentrations
  • Figure 6. Top: Cyclic voltammograms and ECL of [Ru(bpy)3]2+ (1 mmol/L) with caffeine (1 mmol/L). Scanrate: 50 mV/s. ECL-intensity·10
  • Figure 7. Top: ECL-curves from different concentrated caffeine concentrations. Dashed line: ECL-curve from extracted caffeine. Red curve: without caffeine. Bottom: Calibration curve; the arrow shows the ECL-intensity of the coffee extract
  • Figure 8. GC-MS for 10 μmol/L of lidocaine (12.5 min: “L”) and caffeine (13 min: “C”). Experimental conditions: Column: RTX-35 (Restek), carrier gas: Helium, temperature-profile: 100°C (1 min isotherm), temperature-rate: 15°C/min, final temperature: 280°C, 5 min isotherm. Left: Injection volume: 2μL, right: Injection volume: 10 μL