Separation of natural antioxidants using PDMS electrophoresis microchips coupled with amperometric detection and reverse polarity

Abstract

This report describes the use of PDMS ME coupled with amperometric detection for rapid separation of ascorbic, gallic , ferulic, p‐coumaric acids using reverse polarity. ME devices were fabricated in PDMS by soft lithography and detection was accomplished using an integrated carbon fiber working electrode aligned in the end‐channel configuration. Separation and detection parameters were investigated and the best conditions were obtained using a run buffer consisting of 5 mM phosphate buffer (pH 6.9) and a detection voltage of 1.0 V versus Ag/AgCl reference electrode. All compounds were separated within 70 s using gated injection mode with baseline resolution and separation efficiencies between 1200 and 9000 plates. Calibration curves exhibited good linearity and the LODs achieved ranged from 1.7 to 9.7 μM. The precision for migration time and peak height provided maximum values of 4% for the intrachip studies. Lastly, the analytical method was successfully applied for the analysis of ascorbic and gallic acids in commercial beverage samples. The results achieved using ME coupled with amperometric detection were in good agreement with the values provided by the supplier. Based on the data reported here, the proposed method shows suitability to be applied for the routine analysis of beverage samples.

Electrodeposition of reduced graphene oxide on a Pt electrode and its use as amperometric sensor in microchip electrophoresis

“…The linear equations obtained were y = −13.71 + 1.69 x ( R = 0.998) for iodide and y = −3.07 + 0.638 x ( R = 0.996) for ascorbate, where y is the peak current (nA), x is the analyte concentration (μM), and R is the correlation coefficient. The LOD obtained for AA with the proposed Pt‐ERG electrode was lower than some previously published reports using ME‐AD and also voltammetric methods .…”

“…When compared to conventional CE systems, ME devices offer several advantages including shorter analysis times, lower sample consumption, higher throughput capability, portability, and possibility of integrating multiple analytical steps in the same platform . Currently, ME have been largely applied in medical, pharmaceutical and forensic analysis, environmental monitoring and food quality control, coupled with a variety of detection methods, such as LIF, MS, and electrochemical modes as amperometry .…”

Coupling of Independent Electrochemical Reactions and Fluorescence at Closed Bipolar Interdigitated Electrode Arrays

“…These measurements have directi mplications for the use of multiple BPE arrays for parallel, high-throughput detection schemes, such as those neededf or high bandwidth electrochemical detection in molecular separations. [25] 2. Results and Discussion 2.1.…”

Rapid and inexpensive method for the simple fabrication of PDMS‐based electrochemical sensors for detection in microfluidic devices

“…Several types of materials can be employed as electrochemical sensor and coupled to ME for amperometric detection. The most used are metallic electrodes such as platinum and gold , and carbon‐based electrodes in the form of pencil graphite lead , carbon‐ink , composite , carbon fiber , and carbon paste . In comparison with metallic electrodes, the carbon‐based sensors have advantages such as lower cost, larger availability, higher chemical stability, lower overpotential, and wider potential working range .…”