Electrochemical detection peak response

A significant peak must be obtained at range settings of 500 nA to make oxidative electrochemical detection feasible (try both mobile phases and different electrode materials if no response is obtained). 

Fig. 6. (A) The electrochemical detection of hybridization on Au electrode surface. Probe oligonucleotides with 5 -thiol are incubated on the Au surface for 12h. Strong covalent bond between thiols and Au surface results in the formation of the probe-modified electrode (A1), noncomplementary oligonucleotides are incubated with the probe-modified electrode (A2) however, no hybridization takes place between these two strands (A3), the redox label, Hoechst 33258, is incubated with the probe-modified-electrode (A4), since the redox label cannot intercalate with the single-strand probe oligonucleotides on the surface, a small electrochemical current response is obtained (A5). The current intensity at the peak potential (-0.6V) is recorded relative to the background response of the blank buffer solution (dashed grey line). (B) The electrochemical detection of hybridization on Au electrode surface. Probe oligonucleotides with 5 -thiol are incubated on the Au surface for -12 h for the preparation of the probe-modified electrode (B1), target oligonucleotides are...

The modem HPLC system is a very powerful analytical tool that can provide very accurate and precise analytical results. The sample injection volume tends to be a minor source of variation, although fixed-loop detectors must be flushed with many times their volume in sample to attain high precision. Assuming adequate peak resolution, fluorimetric, electrochemical, and UV detectors make it possible to detect impurities to parts per billion and to quantitate impurities to parts per thousand or, in favorable cases, to parts per million. The major sources of error in quantitation are sample collection and preparation. Detector response and details of the choice of chromatographic method may also be sources of error. 

It has been demonstrated that the presence of CNTs greatly increases the oxidation peak current of 6-benzylaminopurine. The CNT-modified electrode is suitable for the determination of trace amounts of benzylaminopurine and has the advantages of high sensitivity, quick response, and good stability [86], Wang et al. have studied the electro-catalytic oxidation of thymine at a a-cyclodextrin incorporated CNT coated electrode in an alkaline media. A sensitive detection scheme for thymine has been further developed by using differential pulse voltammetry [87], The electrochemical determination... 

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