An investigation of electroosmotic flow and pressure pumped luminol chemiluminescence detection for cobalt analysis in a miniaturised total analytical system

The luminol chemiluminescence reaction has been investigated for the determination of cobalt in a planar glass micro reactor. Reagents were mobilised within an etched glass chip with 200 microm wide channels using either electrically driven flow with voltages below 200 V cm(-1) or negative pressure pumping. Surfactants were used to assist mobilisation of the luminol for electrically driven flow and this also increased the chemiluminescence intensity in that system. A calibration over seven orders of magnitude was achieved for cobalt(II) nitrate with the negative pressure pumping system, and the limit of detection at the 95% confidence level was 3 x 10(-11) mol l(-1). The limit of detection for the electrokinetic flow was 4 x 10(-11) mol l(-1) and the linear range was between 10(-10) to 10(-6) mol l(-1). The advantages and disadvantages of both mobilisation methods are discussed for this reaction.