Abstract:The influence of the surfactant hydrophobic chain on selectivity in micellar electrokinetic chromatography was investigated using two sets of surfactants. A series of three sarcosinate surfactants (sodium N‐lauroyl sarcosinate, sodium n−myristoyl sarcosinate, and sodium N‐parmitoyl sarcosinate) with C11, C13, and C15 hydrocarbon tails were compared. In addition, sodium dodecyl sulfate and sodium tetradecyl sulfate were investigated to determine the chain length effect for sodium sulfate surfactants. Linear sol… Show more
“…Likewise, the b and a coefficients are related to the difference in the hydrogen bond donor and acceptor strengths of the aqueous phase and the vesicles, while s and r describe the dipolarity/polarizability and the potential of the pseudophase to interact with solutes' n or π electrons, respectively. The usefulness of the LSER modeling for characterization of the nature of the underlying solute-micelle interactions [7][8][9][10][11][12] and for octanol-water partitioning has already been demonstrated. 13 A set of 41 uncharged aromatic test solutes was used for the LSER modeling (Table 1).…”
Section: Resultsmentioning
confidence: 99%
“…The water molecules that hydrate the vesicle and micelles are the real source of hydrogen bond donating of the pseudophase. Systematic studies of the effect of surfactant structure suggest that the headgroup plays a key role and that the stronger hydration of the aggregates leads to a weaker hydrogen bond donor pseudophase. − Micellar pseudophases are stronger H-bond donors, as indicated by the less negative b coefficients for SDS and SDP. This is quite interesting considering the fact that the chemical compositions of DHP and SDP are very similar, as both consist of alkyl chains and a phosphate headgroup.…”
Solute partitioning into vesicles of dihexadecyl hydrogen phosphate (DHP) was investigated by
electrokinetic chromatography (EKC). The ionic double-chain surfactant forms bilayer structures that
mimic a biological membrane when dispersed in aqueous media. The linear solvation energy relationship
(LSER) was used to gain insights about the nature of interactions and parameters that influence the
partitioning process into vesicles, micelles, and n-octanol. The Gibbs free energies of transfer of selected
functional groups from aqueous to vesicular phases were compared to those in micellar pseudophases of
sodium dodecyl sulfate (SDS) and sodium dodecyl phosphate (SDP). Size and hydrogen bond acceptor
strength of solutes are the main factors that determine their partitioning behavior, while dipolarity and
polarizability play minor, yet significant, roles. It was determined that the cohesiveness of solute
microenvironments in DHP vesicles is between those for micells and n-octanol. Vesicles are weaker hydrogen
bond donors and less dipolar than micelles; however, they interact more strongly with the n and π electrons
of solutes. Interestingly, as the organization of the pseudophase is enhanced from micelles to vesicles, their
microenvironments become closer to that of octanol. Consequently, solute partitioning in vesicle−water
correlates better with that in octanol−water than with that in micelle−water. The influence of the presence
of cholesterol in the bilayer on the interactive nature of the pseudophase was also investigated.
“…Likewise, the b and a coefficients are related to the difference in the hydrogen bond donor and acceptor strengths of the aqueous phase and the vesicles, while s and r describe the dipolarity/polarizability and the potential of the pseudophase to interact with solutes' n or π electrons, respectively. The usefulness of the LSER modeling for characterization of the nature of the underlying solute-micelle interactions [7][8][9][10][11][12] and for octanol-water partitioning has already been demonstrated. 13 A set of 41 uncharged aromatic test solutes was used for the LSER modeling (Table 1).…”
Section: Resultsmentioning
confidence: 99%
“…The water molecules that hydrate the vesicle and micelles are the real source of hydrogen bond donating of the pseudophase. Systematic studies of the effect of surfactant structure suggest that the headgroup plays a key role and that the stronger hydration of the aggregates leads to a weaker hydrogen bond donor pseudophase. − Micellar pseudophases are stronger H-bond donors, as indicated by the less negative b coefficients for SDS and SDP. This is quite interesting considering the fact that the chemical compositions of DHP and SDP are very similar, as both consist of alkyl chains and a phosphate headgroup.…”
Solute partitioning into vesicles of dihexadecyl hydrogen phosphate (DHP) was investigated by
electrokinetic chromatography (EKC). The ionic double-chain surfactant forms bilayer structures that
mimic a biological membrane when dispersed in aqueous media. The linear solvation energy relationship
(LSER) was used to gain insights about the nature of interactions and parameters that influence the
partitioning process into vesicles, micelles, and n-octanol. The Gibbs free energies of transfer of selected
functional groups from aqueous to vesicular phases were compared to those in micellar pseudophases of
sodium dodecyl sulfate (SDS) and sodium dodecyl phosphate (SDP). Size and hydrogen bond acceptor
strength of solutes are the main factors that determine their partitioning behavior, while dipolarity and
polarizability play minor, yet significant, roles. It was determined that the cohesiveness of solute
microenvironments in DHP vesicles is between those for micells and n-octanol. Vesicles are weaker hydrogen
bond donors and less dipolar than micelles; however, they interact more strongly with the n and π electrons
of solutes. Interestingly, as the organization of the pseudophase is enhanced from micelles to vesicles, their
microenvironments become closer to that of octanol. Consequently, solute partitioning in vesicle−water
correlates better with that in octanol−water than with that in micelle−water. The influence of the presence
of cholesterol in the bilayer on the interactive nature of the pseudophase was also investigated.
“…But, when the anionic surfactant changes to sodium lauroyl sarcosine (SLS) which contains a different hydrophilic group −COO - and a comparable hydrophobic chain comparable in molecular structure to that of the SDS molecule, no tubular structure of PANI is obtained in the product, and only micrometer-sized particulates are formed (see Supporting Information, Figure S2). Different from the three above-mentioned surfactants (SDS, SDBS, and AOT) which are demonstrated to be good acidic dopants doping through the electrostatic interaction with polymer chains, , SLS is difficult to use to protonate PANI chains and to dope into the product because of its weak acidity, thereby losing the directing function for constructing PANI rectangular sub-microtubes. 5 SEM images of PANI rectangular sub-microtubes synthesized in the presence of (a) SDBS with the concentration range of 0.57−0.70 mM and (b) AOT with the concentration range of 0.56−0.88 mM.…”
A facile and low-cost approach has been developed for tailoring polyaniline rectangular sub-microtubes as a novel nanostructure of a conducting polymer in dilute sodium dodecyl sulfate (SDS) solution by the oxidation polymerization of aniline at room temperature. It was found that the size and uniformity of polyaniline rectangular sub-microtubes could be appropriately adjusted by tuning the concentration of aniline and the molar ratio of oxidant to aniline, respectively. The morphological evolution of rectangular sub-microtubes under different reaction times has been followed, and a possible formation mechanism has also been discussed in this report. The directing role of other anionic surfactants with -SO3(-) as the hydrophilic group for constructing polyaniline rectangular sub-microtubes has been investigated in detail.
“…The list of potential surrogate chromatographic models, identified as just described, together with the source for the original chromatographic data is assembled in Table 3. [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] The systems are ranked in descending order by the sum of the system constant differences and the list length restricted to the 10 closest fits for any individual biopartitioning process. To achieve diversity in the selection process (near) duplicate systems were eliminated, for example, all the bile salts have similar system constant ratios and can be substituted for each other without much impact on the ranking.…”
A systematic approach for identifing surrogate chromatographic models for biopartitioning processes is described. The method is based on a comparison of the system constant ratios of the solvation parameter model for biopartitioning processes and a database of system constant ratios for reversed-phase liquid chromatographic and micellar electrokinetic chromatographic systems compiled from literature sources. An acceptance filter of < or = 0.2 is applied for each difference in system constant ratio for the compared systems to provide a reasonable probability of success without outputting too many systems with limited predictive properties. Surrogate chromatographic models identified for the non-specific toxicity of neutral organic compounds to the fathead minnow and the soil-water distribution constant are tested by construction of a correlation model for the characteristic property of the biological process and the chromatographic retention factors for a structurally varied group of compounds. Although these models are not the best that could be obtained based on ranking of the differences in system constant ratios the predictive ability of the correlation models is suitable for typical applications and similar to the accepted uncertainty in the measurements of the biological property. Retention factors on the immobilized artificial membrane column (IAM PC DD 2) with 10% (v/v) methanol-water as mobile phase are able to estimate non-specific toxicity to the fathead minnow with a standard error (SE) of 0.22 log units and coefficient of determination (r2) of 0.97 for 31 compounds. Retention factors on a Bakerbond DIOL column with 20% (v/v) acetonitrile-water as mobile phase are able to estimate the soil-water distribution constant with an SE of 0.38 log units and r2 = 0.88 for 59 compounds. Other potential surrogate chromatographic models are identified for non-specific toxicity to the guppy, tadpole, Vibrio fischeri and Terahymena pyriformis as well as the plant cuticle matrix-water distribution constant. On the other hand reversed-phase chromatographic systems seem poorly suited for estimating intestinal absorption and the blood-brain distribution constant.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
