Distribution phenomena of mobile-phase components and determination of dead volume in reversed-phase liquid chromatography

McCormick, Randy M.; Karger, Barry L.

doi:10.1021/ac50064a005

Cited by 429 publications

(197 citation statements)

References 31 publications

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“…In this way carboxy group of phenolic acids can participate in stable H-bond formation as proton donor, especially with MeOH (Alam and Callis 1994). However, concentration of methanol in the stationary phase region of MeOH system is considerably smaller than that of THF system (McCormick and Karger 1980;Gritti et al 2007). The discussed effect is additionally confirmed by the retention data of phenol.…”

Section: Methanol Vs Tetrahydrofuranmentioning

confidence: 82%

“…The three organic solvents, methanol, acetonitrile and tetrahydrofuran, are the most often applied in practice of RP HPLC (reversed-phase high-performance liquid chromatography). These modifiers demonstrate strong extraction into the stationary phase of C18 type in reversed phase systems (McCormick and Karger 1980;Slaats et al 1981;Gilpin et al 1990;Kazakevich et al 2001;Bocian et al 2009). This extraction increases in the order MeOH, ACN and THF.…”

Section: Introductionmentioning

confidence: 99%

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Separation selectivity of some phenolic acids in RP HPLC systems with binary mobile phase comprised various modifiers

Klimek-Turek

Dzido

2010

Adsorption

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Retention of phenolic acid has been correlated for reversed-phase high-performance liquid chromatography systems with different binary mobile phases containing methanol, acetonitrile or tetrahydrofuran as modifiers and buffer at pH 3.0, 4.6 and 5.0. The changes of separation selectivity of solutes, when one modifier is replaced by another in the eluent, has been explained taking into consideration molecular interactions of the solutes with components of the stationary phase region, i.e. extracted modifier, and ordering of the stationary phase by the modifier.Keywords Modifier selectivity · Mechanism of separation selectivity in reversed phase liquid chromatography · Phenolic acids

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Section: Methanol Vs Tetrahydrofuranmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Separation selectivity of some phenolic acids in RP HPLC systems with binary mobile phase comprised various modifiers

Klimek-Turek

Dzido

2010

Adsorption

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“…Many models are proposed to express the analyte distribution between the eluent and the stationary phase. [30][31][32][33] Recent investigations have shown that alkyl chains bonded to the silica surface are densely packed or liquid-like 32) and that methanol forms a monomolecular adsorbed layer on a silica surface on the top of collapsed bonded layer.…”

Section: Resultsmentioning

confidence: 99%

Hydrophobicity Parameters Determined by Reversed-Phase Liquid Chromatography. XV: Optimal Conditions for Prediction of log Poct by Using RP-HPLC Procedures.

Yamagami

Kawase

Iwaki

2002

CHEMICAL & PHARMACEUTICAL BULLETIN

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Recently, in connection with the remarkable development of computational technologies for rational drug designs, the necessity has become apparent of rapid measurement or estimation of molecular properties of chemicals having a potential for medical use. In particular, hydrophobicity (as expressed by the logarithm of 1-octanol/water partition coefficient, log P oct ) is identified as one of the most important properties that govern potencies; its prediction has attracted much attention from medicinal chemists, agrochemists and many investigators in various fields such as pharmacology, toxicology, environmental chemistry and food chemistry. 1,2)Instead of measuring log P oct by the standard but time-consuming shake-flask method, reversed-phase chromatography (RP-HPLC) has increasingly been used as a powerful tool to predict log P oct from the readily accessible retention factor, log k, (given by kϭ(t R Ϫt 0 )/t 0 where t 0 and t R express elution times of the non-retained substance and sample, respectively).Extensive studies have been made to establish an optimal RP-HPLC system providing a good linearity between log P oct and log k.3-10) Many workers have used an ODS-type column with methanol-water mobile phases to obtain a normalized parameter, log k W (k W : the retention factor extrapolated to 0% organic modifier), as an alternative to log P oct . 3,5,8) In our experience, this log k W approach works well for non-polar solutes but tends to provide overestimated log P oct values for strong H-acceptors. [10][11][12][13][14][15] From systematic studies of log k obtained under various HPLC conditions for typical heteroaromatic compounds such as (di)azines, furans and thiophenes, we were led to the conclusion that the use of an eluent containing around 50% methanol, which usually provides a more direct correlation with log P oct , is the most convenient and practical procedure for rapid estimation of log P oct provided H-donors (amphiprotic compounds) are treated separately.11-15) Our results so far obtained are illustrated graphically in Fig. 1. This conclusion has been derived from the following results.First, we have shown that, for each series of monosubstituted (di)azines, log P oct can be excellently correlated with log k in different compositions of methanol-water eluents by a general formula Eq. 1 containing two terms correcting for H-bonding effects: 16) log kϭalog P oct ϩrs I ϩsS HA ϩconst.( 1) where the s I parameter represents the Charton's inductive electronic substituent constant, 17) and S HA designates the substituent H-acceptor scale that we have recently defined where the value of S HA is set at unity for H (the unsubstituted * To whom correspondence should be addressed. The use of log k derived from reversed phase (RP)-HPLC retention times provides a convenient method for estimating log P oct values (P oct : 1-octanol/water partition coefficient). In order to establish optimal HPLC conditions, the difference between chromatographic (C18 modified column and aqueous methanol eluents) and bulk solve...

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“…[15][16][17][18] The mobile phase velocity, which varied along the conical column, was u 1 at the inlet and u n at the outlet of the column. The relation between the initial and final velocity was u n =Mu 1 , where M represents the ratio between the cross-sectional area at the inlet and at the outlet of the column (M=A 1 /A n ).…”

Section: Resultsmentioning

confidence: 99%

Conically Shaped Chromatographic Column

Pečavar

Vovk²,

Marsel³

et al. 1999

ANAL. SCI.

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We investigated a column with varying physical properties. A change in velocity was induced by a continuously varying the diameter inside the column. Analytical dimensions of the column were used. The diameter was continuously reduced from the analytical one (4.0 mm) to a diameter typical for narrow-bore columns (2.5 mm). Our interest was focused on the efficiency of a conical column and on the mobile phase velocity in it. The results obtained with the conical column were compared to those obtained with the conventional analytical column and the narrow column. The diameter of the narrow column (3.3 mm) was the same as the average diameter of the conical column. The advantage of the conical column over the narrow column was the greater loadability of the conical column and better dynamic efficiency. Compared to the conventional analytical column, a higher linear velocity at the same flow rate was achieved. Therefore, the retention times were shorter and consumption of the mobile phase was smaller.

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Distribution phenomena of mobile-phase components and determination of dead volume in reversed-phase liquid chromatography

Cited by 429 publications

References 31 publications

Separation selectivity of some phenolic acids in RP HPLC systems with binary mobile phase comprised various modifiers

Separation selectivity of some phenolic acids in RP HPLC systems with binary mobile phase comprised various modifiers

Hydrophobicity Parameters Determined by Reversed-Phase Liquid Chromatography. XV: Optimal Conditions for Prediction of log Poct by Using RP-HPLC Procedures.

Conically Shaped Chromatographic Column

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