Solute–solvent interactions on the surface of reverse phases. Interactive characteristics of some short-chain aliphatic moderators having different functional groups

Abstract

The desorption-adsorption coefficients and distribution coefficients of a series of aliphatic alcohols, carboxylic acids and aldehydes between water and ODs2 reverse phase have been determined using a chromatographic procedure. The moderator concentrations over which the measurements were made were kept at sufficiently low levels so that moderator/moderator interactions in the mobile phase and moderator interactions with adsorbed moderator were kept minimal.It is shown that the desorption-adsorption coefficients decrease and the distribution coefficients between water and the reverse phase increase exponentially with the carbon number of the moderator confirming the system can be described by the Martin equation. As a result, substances having chains of five carbon atoms or more could produce complete coverage of the surface when present at a level of only a few percent in the mobile phase. Thus, the surface of the reverse phase can be strongly modified without significantly affecting the solvent characteristics of the mobile phase. It was shown that dispersive interactions between the reverse phase and the hydrocarbon chain of the moderator were the same for each moderator and from the slope of the log K against carbon-number curves, it was also shown that the logarithmic increment for each methylene group in the alkyl chain was the same for all moderators and independent of the functional group. The difference in the distribution coefficients between different moderators having alkyl chains of the same length depends solely on the dispersive interactions between the functional groups with the reverse phase and the functional group with any residual silanol groups that may be present. The method used can also determine the effective chromatographic surface area of a given reverse-phase column. It is suggested that the technique could also be used to determine the effective surface area of different types of bonded phases, give a measure of the residual polarity of the stationary phase and the magnitude of the interactive capacity of the hydrocarbon portion.

Effects of organic modifier and temperature on micellar liquid chromatography

“…Thus, the organic modifier has altered the stationary phase and the micellar mobile phase, supporting Dorsey's claim that the stationary phase has been "wetted" by the addition of organic modifier (7), which is in agreement with the equilibrium data cited previously. Further support of altering the stationary phase is given by Scott and Simpson, where it was noted by adsorption isotherms that over 90% of the CIS column is covered with propanol a t a concentration of 3% (w/v) (22). The altering of the micellar mobile phase is supported by the retention and the K 2 equilibrium data.…”

Photostabilization of Polymers

“…Many reviews on thermal102, 103,126,241,299,482,531,540,699,841,1001,1007,1012,1016,1017,1019,1020 and photo-stabilization 34 ,35,52,241,279,313,341,479,541,548,552,652, 1008,1117,1154,1155 and books on polymer stabilization 283 ,375,428,483,485, 530,532,611,685,842,934,1043,1057,1076,1135 have been published. The present list of commercially available photostabilizers is given in Appendix 2.…”

Adsorption and recovery issues of recombinant monoclonal antibodies in reversed-phase liquid chromatography†

“…Two solutions were proposed to reduce the specific adsorption phenomenon of mAbs, including the use of high mobile‐phase temperature (up to 80–90°C) and/or the addition of ancillary solvents (e.g., 1–3% n ‐butanol) to the mobile phase . This last strategy was previously described by Scott and Simpson in the 1980s and recently updated to reduce the time required for column equilibrium between successive RPLC gradients. Scott and Simpson first described the strong adsorption of n ‐butanol at the surface of the stationary phase .…”