A dynamically modified microfluidic poly(dimethylsiloxane) chip with electrochemical detection for biological analysis

Separation and direct detection of amino acids, glucose and peptide in a 3.1 cm separation channel made of poly(dimethylsiloxane) (PDMS) with end‐column amperometric detection at a copper microdisk electrode was developed. This system is the integration of a normal sized working electrode with electrochemical detection on a PDMS microfabricated device. The PDMS channels dynamically modified by 2‐morpholinoethanesulfonic acid (MES) show less adsorption and more enhanced efficiency than that of unmodified ones when applied to separations of these biological molecules. The migration time is less than 100 s and the reproducibility of migration time is satisfactory with relative standard deviation (RSD) of 2.8% in 19 successive injections. The limits of detection of arginine (Arg), glucose, and methionine‐glycine (Met‐Gly) are estimated to be 2.0, 8.5, and 64.0 νM at S/N = 3, approximately 0.5–16.0 fmol, respectively. Variances influencing the separation efficiency and amperometric response, including injection, separation voltage, detection potential, or concentration of buffer and additive, are assessed and optimized.