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

Abstract

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 μm 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 × 10⁻¹¹ mol l⁻¹. The limit of detection for the electrokinetic flow was 4 × 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.