| High performance capillary electrophoresis (HPCE) is a type of new technique of separation. The basic theory of HPCE is that to separate mixed substances by the difference of electromigration of the electriferous in electric field. In recent years, HPCE has been one of the most rapid developed studying area of analytical chemistry because of its special characteristics.Semi-differential Voltammetry is to record the correlation curve of the semi-differential value of the Ampere current and the value of potential. And it includes 1.5th-differential voltammetry and 2.5th-differential voltammetry, also record the correlation curve of the 1.5th-differential value, 2.5th-differential value of the Ampere current with the value of potential. It obviously improve the resolving capability and the sensitivity. As higher order of differentials, the resolving capability and the sensitivity will be better.It has many studies on wavelet transform to resolve the problems of noise and base curve excursion in electrochemical detection system. Wavelet transform is called" mathematics microscope" because it can decompose chemical signals into multi-scaled elements and use corresponding sampling steps according different scaled elements to focus on any parts of signals.Using the Semi-differential Voltammetry electrochemical detection system constructed by ourselves, we detect three kinds of amino acids. And using the method of wavelet transform, we separate out the complex signals and get the result of the linearity of three kinds of amino acids is 1.67 × 10-3 -5.43 × 10-7mol/L, and the limit of detection(LOD) is5.43 × 10-7 mol/L (S/N=3) , r=0.998. And we study the LOD of Thr, under 1.5th-differential voltammetry, the LOD is 1.91 × 10-8 mol/L;under 2.5th-differential voltammetry, the result is 4.76 × 10-9 mol/L.
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