in the spectrum of lasalocid, which is assigned to ( -+ Na)Na+. With monensin spotted on a TLC plate, the sensitivity of detection was established as well below 0.1 µg.A major concern was the possible interference related to the components in the TLC adsorbent and the masking tape. However, no background interference was observed in the mass range of interest based on blank tests of both fluorescent and nonfluorescent TLC plates and direct tests of the masking tape. Also, contamination of the ion source by the TLC adsorbent, i.e., silica gel, was not observed. However, after the depletion of the FAB matrix liquid, the flake of adsorbent from plastic-backed TLC sheets appeared to remain intact while that from glass TLC plates tended to disintegrate. For this reason we favor the Use of plastic-backed TLC sheets.In conclusion, we have demonstrated a simple and rapid method for directly obtaining FAB spectra of TLC fractions which circumvents the problems associated with the previously cited methods.
ACKNOWLEDGMENTWe wish to thank D. B. Borders and . T. Lee of Lederle Laboratories, American Cyanamid Company, for providing the coccidiostats and the TLC separation procedure.LITERATURE CITED(1) Deverse, F.
Fundamental characteristics of a new type of chromatography with micellar solutions of ionic surfactants were examined.Electrokinetic phenomena In open-tubular capillaries move two phases, aqueous and micellar, with different velocities and micellar solubilization operates as the distribution process of solutes. Sodium dodecyl sulfate (SOS) solutions and a 0.05 mm l.d. X 650 mm fused silica tube were employed and high dc voltages up to 25 kV were applied. Linear relationships were observed between current and migration velocities of water, micelle, and any solute, but not between applied voltages and the velocities. This discrepancy can be reasonably Interpreted In terms of the temperature rise of the solution In the tube resulting from Joule heating. Optimum resolutions can be obtained when the capacity factor Is about 2, because retention times are limited between those of an insolublllzed solute or water and a totally solubilized solute or micelle. Observed dependence of capacity factors on current can also be explained by the temperature rise. Thermodynamic parameters in micellar solubilization were presented.
This review highlights recent developments and applications of on-line sample preconcentration techniques in capillary electrophoresis (CE) from 2010 to April 2013. Various preconcentration techniques based on the analyte velocity change in two or three discontinuous solutions system including field-amplified stacking, transient isotachophoresis, pH-mediated stacking, sweeping, and their modified and combined techniques have been employed to enrich and separate biological, environmental, food, toxicological, forensic and nanoparticle samples in CE. More than 170 published research articles collected from Scopus databases from the year 2010 described the on-line sample preconcentration techniques. This review provides comprehensive tables listing the applications of the on-line sample preconcentration techniques with categorizing by the fundamental preconcentration mechanism and application area.
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