Effect of mobile phase composition and highly fluorinated bonded phases on the apparent free energy of transfer of solute functional groups

Sadek, Paul C.; Carr, Peter W.; Ruggio, Michael J.

doi:10.1021/ac00134a022

Cited by 42 publications

(19 citation statements)

References 14 publications

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“…We can see that the decyl column produces the highest selectivities and the fluorinated (CH 2 ) 2 C 6 F 13 and (CH 2 ) 3 OC 3 F 7 phases produce the lowest selectivities, which is in agreement with previous results since both solutes are quite small. 15,16 The absence of any molecular shape term and the reliance of the LSER exclusively on molecular volume and not molecular surface area is a very real limitation of the approach. It is very well-known, both theoretically 67 and experimentally, that shape and molecular area [68][69][70] are more important in establishing solubility in water and octanol-water partition coefficient than is the molecular volume.…”

Section: Resultsmentioning

confidence: 99%

Comparative Study of Hydrocarbon, Fluorocarbon, and Aromatic Bonded RP-HPLC Stationary Phases by Linear Solvation Energy Relationships

et al. 1999

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The retention properties of eight alkyl, aromatic and fluorinated reversed-HPLC bonded phases were characterized through the use of Linear Solvation Energy Relationships (LSERs). The stationary phases were investigated in a series of methanol-water mobile phases. LSER results show that solute molecular size under all conditions and hydrogen bond acceptor basicity are the two dominant retention controlling factors and that these two factors are linearly correlated when either different stationary phases at a fixed mobile phase composition or different mobile phase compositions at a fixed stationary phase are considered.The large variation in the dependence of retention on solute molecular volume as only the stationary phase is changed indicate that the dispersive interactions between nonpolar solutes and the stationary phase are quite significant relative to the energy of the mobile phase cavity formation process.Principal Component Analysis (PCA) results indicate that one PCA factor is required to explain the data when stationary phases of the same chemical nature (alkyl, aromatic and fluoroalkyl phases) are individually considered. However, three PCA factors are not quite sufficient to explain the whole data set for the three classes of stationary phases. In spite of this, the average standard deviation obtained by the use of these principal components factors are significantly smaller than the average standard deviation obtained by the LSER approach. In addition, selectivities predicted through the LSER equation are not in complete agreement with experimental results.These results show that the LSER model does not properly account for all molecular interactions involved in RP-HPLC. The failure could reside in the V 2 solute parameter used to account for both dispersive and cohesive interactions since "shape selectivity" predictions for a pair of structural isomers are very bad.

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Section: Resultsmentioning

confidence: 99%

Comparative Study of Hydrocarbon, Fluorocarbon, and Aromatic Bonded RP-HPLC Stationary Phases by Linear Solvation Energy Relationships

et al. 1999

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“…In some of the earliest retention models, such as those based on interaction indices, the mobile phase has been considered to be the key element controlling elution and the bonded phase treated as a passive acceptor of the solute (1)(2)(3)(4). In other models, molecular interactions in the stationary phase have been recognized as important contributing factors (5)(6)(7)(8). However, adequate descriptions of how these interactions are affected by intercalated solvents are often missing.…”

Section: Introductionmentioning

confidence: 99%

Studies of the surface composition of phenyl and cyanopropyl bonded phases under reversed-phase liquid chromatographic conditions using alkanoate and perfluoroalkanoate esters

Gilpin¹,

Jaroniec²,

Lin³

1991

Anal. Chem.

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Two polar bonded phases, phenyl-silica and cyanopropylsllica, have been studied under reversed-phase conditions using homologues of alkanoate and perfluoroalkanoate esters as test solutes. For comparative purposes a similarly prepared n -butyl phase also has been studied under equivalent conditions. Retention measurements have been carried out as a function of mobile-phase composition for water-methanol and water-acetonitrile and Incremental methylene (-CH2-) and perfluoromethylene (~CF2~) selectlvltles calculated. These latter data have been used to estimate the thermodynamic constant K^, which describes the sorption equilibrium of solvents between mobile and stationary phases assuming Ideality of these phases. For water-methanol, differences In composition between the mobile and surface phases due to preferential Intercalation are small. However, the data Indicate a significant sorption excess of acetonitrile by the bonded phases. This preferential sorption of acetonitrile Is greatest for alkyl phases and decreases with increasing polarity of the bonded phase (l.e., cyano-silica < phenyl-silica < alkyl-silica).

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“…These specific interactions were also noticed in HPLC, even when only few fluorine atoms were present in the solute. A dramatic increase in the capacity factor of fluorinated derivatives was observed with respect to its hydrocarbon analogue (13)(14)(15). The evaluation of such new phases was studied with aromatic hydrocarbon solutes ( 14) and, recently, with 42 different solutes of various nature (15).…”

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Highly fluorinated stationary phases for analysis for polyfluorinated solutes by reversed-phase high-performance liquid chromatography

Krafft¹,

Jeannaux²,

Blanc³

et al. 1988

Anal. Chem.

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Two perfluorinated stationary phases were prepared by reacting two perfluoroalkyl amlnosilanes (RFC2H4SI(CH3)2N-(CH3)2 with Rf = C8F17 or C10F21) with Lichrosorb S1100 (10 µ ). The chromatographic properties of such stationary phases were checked with perfluoroalkylated series and corresponding hydrogenated series of compounds and compared with a classical C18 stationary phase. The perfluoroalkylated series Included Iodides (RFI), iodoethanes (RFCH2CH2I), and ethenes (RFCH=CH2), RF ranging from C2F5 to C10F21. The plots of log k', the capacity factor, versus the number of carbon atoms produced straight lines for each series and each stationary phase. With a ternary THF-DMF-water (200/50/70 (v/v/v)) mobile phase, the transfer energy per CF2 group was found to be about 1 kJ/mol, with the fluorinated stationary phases, compared to only about 0.35 kJ/mol with the hydrogenated stationary phase. It was also 0.35 kJ/mol for a CH2 group, whatever the phase. This leads to significant Increases In retention times and separation factors of the perfluoroalkylated compounds on the fluorinated phases. The analytical capabilities of such phases were demonstrated by two examples of fluorinated surfactant analysis.

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Effect of mobile phase composition and highly fluorinated bonded phases on the apparent free energy of transfer of solute functional groups

Cited by 42 publications

References 14 publications

Comparative Study of Hydrocarbon, Fluorocarbon, and Aromatic Bonded RP-HPLC Stationary Phases by Linear Solvation Energy Relationships

Comparative Study of Hydrocarbon, Fluorocarbon, and Aromatic Bonded RP-HPLC Stationary Phases by Linear Solvation Energy Relationships

Studies of the surface composition of phenyl and cyanopropyl bonded phases under reversed-phase liquid chromatographic conditions using alkanoate and perfluoroalkanoate esters

Highly fluorinated stationary phases for analysis for polyfluorinated solutes by reversed-phase high-performance liquid chromatography

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