Microchip capillary electrophoresis coupled to sinusoidal voltammetry for the detection of native carbohydrates

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Abstract
The development of a microchip electrophoresis system involving integrated frequency based electrochemical detection is described. The use of poly(dimethylsiloxane) (PDMS) as the channel substrate greatly simplifies the fabrication process while decreasing cost and time consumption. Characterization of this system is accomplished through the detection of native carbohydrates at planar copper electrodes. Various photolithographic techniques are explored in the optimization of electrode area. Separation efficiency of 1×105 theoretical plates per meter is demonstrated. Sinusoidal voltammetry utilizes information in the frequency domain to achieve sensitive detection through either of two approaches, maximization of signal or minimization of noise. Mass detection limits (S/N = 3) of less than 200 amol have been accomplished for glucose and sucrose. Sinusoidal voltammetry also facilitated the selective isolation of an analyte signal from a pair of chromatographically unresolved species through the use of phase discrimination.