The Dielectric Constant of Solutions of Dipolar Ions.

Wyman, Jeffries

doi:10.1021/cr60064a005

Cited by 81 publications

(39 citation statements)

References 18 publications

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“…These results show that the variation in the concentration of urea in the eluent seemingly alters the retention of the solutes in a manner similar to the conventional methanol-water mobile phase. However, it should be stressed that the addition of urea gives rise to a very slight change in the dielectric nature of the aqueous urea solution, 26 which is the entire difference to the aqueous methanol system.…”

Section: Addition Of Urea In a Neat Aqueous Nacl Mobile Phasementioning

confidence: 99%

“…4. A high permittivity and viscosity of an aqueous urea solution 26,32 is indicative of the existence of strong cooperative structures between urea and water through hydrogen bonding. 33 It does not seem that urea or guanidium ion is directly adsorbed on the superficial alkyl chains on the 850 ANALYTICAL SCIENCES JULY 2001, VOL.…”

Section: Effect Of Water Structure Breaker Agents On the Solvation Ofmentioning

confidence: 99%

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The Use of Water Structure Breakers, Urea and Guanidium Chloride, New Mobile Phase Modifiers in Reversed-phase Partition High-Performance Liquid Chromatography

2001

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IntroductionToday, RP-HPLC employing a hydrocarboneous bonded stationary phase, typically an n-octadecyl silanized packing surface with a hydro-organic mobile phase, has been quite popular for the separation of a wide variety of mixtures. The RP-HPLC separation processes are thought to be controlled by the so-called hydrophobic interaction 1 at work on phasepartitioning event of solute molecules between the mobile and stationary phases. Because the retention of solutes depends on the solute-solvent interaction, 2,3 manipulation of the organicsolvent content in the mobile phase is reasonably important. In addition, the stationary phase also plays a highly active role in chromatographic processes. It has been speculated that as the content of an organic solvent in a mobile phase decreases, the bending and tangling of alkyl chains on the particle surface take place through a hydrophobic interaction, 4 which doubtless reduces the separation efficiency. Modifiers in the mobile phase, which are employed for the benefit of separation improvement, strongly affect RP-HPLC processes in two ways: partitioning of the solutes and solvation of the stationary phase.The interaction between the nonpolar moiety of a molecule and water, the so-called hydrophobic interaction, is an important factor in many physicochemical processes: for example, protein denaturation, 5-7 surfactant micellization and absorption. 8 More basically, the slight solubility of hydrocarbon liquids in water is easy to observe but unexpectedly difficult to explain. 9 It is generally accepted that the hydrophobic interaction is due to an increased "ordering" or "structuring" of water molecules in the close vicinity of a nonpolar solute. 10Thus a very common conclusion is that the small solubility of nonpolar solutes in water results from this entropy-unfavorable structuring processes. Here, we define an additive which destroys the structure of pure water as a "water structure breaker", 11 such as urea and guanidium chloride (GuCl). In fact, that the longrange order inherent in water solvent is destroyed in urea solution has been demonstrated using nuclear magnetic resonance spectroscopy. 12 Urea and GuCl are also well-known as powerful protein denaturants. [13][14][15][16] In addition, the solubilities of some hydrocarbons in water increase in the presence of urea. 11,17 An explanation for this phenomenon is that the breakup of a strengthened water structure ("iceberg" structure 18 ) around the nonpolar solutes is quite readily achieved by the "hydrophobic interaction breakers". So far, most investigations of water structure-breaking agents have been focused on their effects on some physicochemical phenomena: micelle formation, 19,20 self-association of dyes, 21 protein denaturation, etc. In contrast, there have been few studies that utilized water structure-breaking agents in separation techniques. Urea has often been used only as a denaturant or an unfolding agent in the hydrophobic interaction chromatography of protein. Organic solvent-free mobile-phase sy...

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Section: Addition Of Urea In a Neat Aqueous Nacl Mobile Phasementioning

confidence: 99%

Section: Effect Of Water Structure Breaker Agents On the Solvation Ofmentioning

confidence: 99%

The Use of Water Structure Breakers, Urea and Guanidium Chloride, New Mobile Phase Modifiers in Reversed-phase Partition High-Performance Liquid Chromatography

2001

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“…{>ersion region on the low frequency side. Wyman in his work on ammo acids and related compounds [5] with molecular weights as high as 150 found no evidence of anomalous dispersion at wave lengths down to 2.5 m (120 Mc). The molecular weights of the benzein derivatives discussed in this paper are between 350 and 400, but the lowest frequencies used (27 m or 11 Mc) are less than onetenth of those just mentioned.…”

Section: Sources Of Errormentioning

confidence: 99%

Polar structure of some benzein indicators

Elliott¹,

Acree²

1939

J. RES. NATL. BUR. STAN.

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In the study of electronic effects associated with changes of color of indicators, the approximate electric moments have been measured for a-naphtholbenzein and thymolbenzein in benzene solution. The values obtained were 4.3 X 10-18 and 6.8 X 10-18 esu, respectively. These values are much lower than those predicted for the benzein type of molecule on the basis of t he static dipolar structure shown in figure 2. They are compatible, however, with the quinone-phenolate resonance theory and indicate that these molecules are predominantly in the structure shown as Air figure 1, with very little of the resonant dipolar form A 2•

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“…В системах с большой диэлектрической постоянной растворителя ε* уравнение Клаузиуса -Мосотти не выполняется, а вместо него исполь-зуют уравнение 43 ε -8° -а Ъ где а и Ъ -константы. На основании этих соображений получается тот же результат Итак, зная молекулярный вес исследуемого белка, можем найти диполь-ный момент молекулы μ на основании измерений низкочастотного инкремента и высокочастотного декремента.…”

Section: Sunclassified

Dielectric constants of biological objects

Sedunov¹,

Frank-Kamenetskii²

1963

Usp. Fiz. Nauk

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The Dielectric Constant of Solutions of Dipolar Ions.

Cited by 81 publications

References 18 publications

The Use of Water Structure Breakers, Urea and Guanidium Chloride, New Mobile Phase Modifiers in Reversed-phase Partition High-Performance Liquid Chromatography

The Use of Water Structure Breakers, Urea and Guanidium Chloride, New Mobile Phase Modifiers in Reversed-phase Partition High-Performance Liquid Chromatography

Polar structure of some benzein indicators

Dielectric constants of biological objects

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