Fabrication of a Magnet-Assembled Alignment Device for the Amperometric Detection of Carbohydrates in Combination with CE

Abstract

The article describes the preparation of a magnet-assembled alignment device for the amperometric detection of carbohydrates in combination with capillary electrophoresis (CE). It consists of a self-positioning copper disc detection electrode plate, an NdFeB magnet, a painted iron screw nut as well as a cap bearing a grounding electrode, an auxiliary electrode and a reference electrode. Coaxially aligned copper wire and stainless steel tube were enclosed between two poly(methyl methacrylate) plates by far infrared-assisted encapsulation to fabricate the self-positioning electrode plate. The performance and advantages of the alignment device were demonstrated by the separation and detection of standard mixtures of mannitol, sucrose, glucose and fructose by CE. The four carbohydrates were well separated within 13 min in a 40-cm long capillary at a separation voltage of 9 kV using a 75 mM NaOH aqueous solution. Good linearity was observed between the peak current and concentration of carbohydrates over three orders of magnitude with detection limits (S/N = 3) ranging from 0.7 to 0.9 µM. The present system exhibited long-term stability and reproducibility with relative standard deviations of less than 5% for peak currents (n = 15). The advantages of the magnet-assembled alignment device include its simple design and construction, high alignment reproducibility, ease of operation, high degree of integration, portability and low cost. The method has been successfully applied in the determination of carbohydrates in Zingiber officinale Roscoe. Coaxially aligned copper wire and stainless steel guiding tube were enclosed between two PMMA plates by far infrared-assisted encapsulation to prepare self-positioning copper disc detection plate that was sandwiched between a magnet and a painted iron screw nut to form magnet-assembled alignment device for the amperometric detection of capillary electrophoresis.