Effective screen-printed potentiometric devices modified with carbon nanotubes for the detection of chlorogenic acid: application to food quality monitoring

All-solid state screen-printed electrodes were fabricated for chlorogenic acid (CGA) detection. The screen-printed platforms were modified with multi-walled carbon nanotubes (MWCNTs) to work as a lipophilic solid-contact transducer. The sensing-membrane was plasticized with a suitable solvent mediator and incorporating [Ni-II(bathophenanthroline)(3)][CGA](2) complex as a sensory material. In a 30 mM phosphate solution (buffer, pH 6), the sensor revealed a Nernstian-response towards CGA ions with a slope of -55.1 +/- 1.1 (r(2) = 0.9997) over the linear range 1.0 x 10(-7) to 1.0 x 10(-3) (0.035-354.31 mu g mL(-1)) with a detection limit 7.0 x 10(-8) M (24.8 ng mL(-1)). It revealed a stable potentiometric response with excellent reproducibility and enhanced selectivity over several common ions. Short-term potential stability and the interfacial sensor capacitance was estimated using both electrochemical-impedance spectroscopy (EIS) and chronopotentiometry techniques. The presented electrochemical platform revealed the merits of design simplicity, ease of miniaturization, good potential-stability, and cost-effectiveness. It is successfully applied to CGA determination in different coffee beans extracts and juice samples. The data obtained were compared with those obtained by liquid chromatography reference method (HPLC).

Automated summary

A novel all-solid state screen-printed electrode was developed for chlorogenic acid detection by modifying with multi-walled carbon nanotubes and suitable sensing membrane. The electrode showed Nernstian-response and high sensitivity towards CGA ions in coffee bean extracts and juice samples, demonstrating good stability and selectivity.