A compact and low-cost miniaturized analysis system composed of microchip electrophoresis and chemiluminescence detection manipulated by a simple subatmospheric pressure fluid-driven device

Abstract

A portable and low-cost miniaturized analysis system was proposed, in which microchip electrophoresis (MCE) and chemiluminescence (CL) were used as the separation and detection units, respectively. A porous monolithic plug was created in the separation channel of the microchip as a select valve, which prevented the pressure-driven CL reagents flowing back into the separation channel but allowed electrophoretic migration along the separation channel. The sensitivity was greatly enhanced by improving the mixing efficiency using a spiral detection channel with an increased length facing the photomultiplier tube (PMT). Peak width could be significantly reduced by increasing the flow rate of CL reagents. Putting grounding electrode before the detection channel significantly improved the reproducibility. A simple and compact subatmospheric pressure fluid-driven device was developed for manipulating the whole analytical process, including variable-volume sample loading, electrophoretic separation and CL reagents transportation. All miniaturized components for constructing a portable MCE-CL system are commercially available. This approach considerably simplified the operation and equipments for constructing an efficient MCE-CL system. Nine metal cations, such as Cr(III), Co(II), Cu(II), Ni(II), Au(III), Mn(II), Zn(II), Pt(II), Pb(II) were successfully separated within 200 s. Migration time precisions ranging from 0.39% for Cr(III) to 2.1% for Cu(II) were obtained for ten consecutive determinations with peak height precisions from 1.67% for Co(II) to 5.73% for Pb(II). Detection limits ranging from 7.5 × 10⁻¹¹ mol L⁻¹ for Co(II) to 8.3 × 10⁻⁹ mol L⁻¹ for Pb(II) were achieved, which were about three orders lower than the present MCE-CL system. It has been applied for the determination of metals in tea. The results with the recoveries from 97.0% to 102.3% proved that the proposed MCE-CL system offers a number of benefits including miniaturization, high sensitivity and better resolution.