PubMed · 4697921
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T Tenforde, E J Clarke, R D MacGregor, M J Streibel, P W Todd. 1973. A convenient microelectrophoresis assembly.. https://doi.org/10.1007/bf02478161
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Hydroquinone was found to suppress bubble formation at the outlet electrode of a sheathless capillary electrophoresis/electrospray ionization-mass spectrometer by replacing the oxidation of water (2H2O(1)<-->O2(g) + 4H+ + 4e) with that of more easily oxidized hydroquinone (hydroquinone<-->p-benzoquinone + 2H+ + 2e). Formation of p-benzoquinone replaces the formation of oxygen gas, effectively suppressing gas bubble formation. Several electrode materials, including platinum, gold-coated stainless steel, and stainless steel wires, were tested. However, hydroquinone suppressed bubbles only at the platinum electrode. Combination of the in-capillary electrode sheathless interface using platinum wire, hydroquinone as a buffer additive, and pressure programming at the inlet of the capillary electrophoresis provided a rugged high efficiency interface for analysis of protein digests using CE/ESI-MS.
Dark ground optical microscopy, electron microscopy, and high performance liquid chromatography (HPLC) have been used to quantify the effects of formulation changes on the phase inversion dynamics and in vitro drug release properties of a PLGA-based drug delivery system. Gel growth rates and water influx rates are determined from plots of the square of the respective front motion with time. Results show that additives that accelerate the solution gelation rate at constant morphology result in high initial release rates. Conversely, additives that slow the rate of gelation dramatically reduce the initial drug release rate and lead to a more dense sponge-like morphology. Moreover, the phase inversion dynamics and morphology are the same regardless of whether the solutions are quenched with water, a PBS buffer solution or horse serum.
The analysis of nucleosides and nucleotides have in most cases been performed by HPLC using either reversed-phase HPLC with gradient elution or using reversed-phase ion-pair chromatography. In this paper we have explored the possibility of using capillary electrochromatography (CEC) in order to avoid the use of gradients or ion-pairing reagents. CEC is in many ways comparable to HPLC, but CEC is theoretically able to provide better separations due to the higher efficiency caused by the flowfront being more plug-like as also is the case in CE, which is to be compared to the more parabolic flow observed in HPLC. The separation of six nucleosides (adenosine, cytidine, guanosine, inosine, thymidine and uridine) was investigated with respect to concentration of buffers, pH, amount of acetonitrile, temperature and voltage in order to optimise the separation. Baseline separation was achieved for the six nucleosides in less than 13 min using a background electrolyte consisting of (5 mM acetic acid, 3 mM triethylamine, pH 5.0)-acetonitrile (92:8, v/v).