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A new method to introduce the concentration gradient into the capillary has been developed and its application to DNA capillary electrophoresis is presented. The concentration gradient produced by mixing 5% w/v polyacrylamide-co-poly(N-dimethylacrylamide) (PAM-co-PDMA) solution and 1 x Tris/N-tris(hydroxymethyl)methyl-3-amino-propanesulfonic acid/EDTA (TT) + 5 M urea buffer was successfully achieved by using two programmable syringe pumps with strict control of dead volume, flow rate, and pressure balance. This method has the advantages of high stability, reproducibility, and versatility. The column with concentration gradient greatly improved the resolution, especially for the large DNA fragments, due to a decrease in band width broadening with time. A column containing 2-4% w/v gradient in four steps had a longer read length, shorter separation time and better resolution (after 380 base) than that of 4% w/v single concentration polymer solution. The number of steps in the gradient had almost no effect on the performance. The change in the average concentration by relocating the position of the same step gradient, i.e., a combination of different low concentration to high concentration polymer solution ratios, resulted in a different migration time, read length and resolution. 相似文献
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Rampf E Schröder U de Wette FW Kulkarni AD Kress W 《Physical review. B, Condensed matter》1993,48(14):10143-10152
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John L. Huston Robert G. Scott Martin H. Studier 《Journal of mass spectrometry : JMS》1976,11(4):383-387
Fluorination of bituminous coal by elemental fluorine yields a solid product from which a solid distillate can be made by vacuum pyrolysis. Both fluorinated materials are easily made and are useful for mass spectrometric unit mass assignments. They have certain advantages over the commonly used perfluorokerosene, particularly for use in the high mass region. 相似文献
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J J Katz H H Strain A L Harkness M H Studier W A Svec T R Janson B T Cope 《Journal of the American Chemical Society》1972,94(22):7938-7939
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