Evaluation of a rapid technique for measuring the diffusion coefficients of small molecules

Abstract

The diffusion coefficients of sucrose, glycol, and glycine in water have been measured at 25.OoC by using the schlieren optical system of a preparative ultracentrifuge. The schlieren optical system was modified by the incorporation of a 35 mm single lens reflex camera. The values obtained were well within 2% of values found in existing literature and had an intrinsic precision of better than 2%.

Effects of hydroxyl groups on binary diffusion coefficients of α-amino acids in dilute aqueous solutions

“…The binary diffusion coefficient, D 12 , is one of the most important physical properties in estimating mass transfer rates. There are many reports on D 12 measurements of ␣-amino acids in aqueous solutions [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. However, few D 12 data of ␣-amino acids containing hydroxyl groups are available in the literature [2,4,14,15].…”

Infinite Dilution Binary Diffusion Coefficients of Several α-Amino Acids in Water over a Temperature Range from (293.2 to 333.2) K with the Taylor Dispersion Technique

“…Binary diffusion coefficients (D 12 ) for R-amino acids, of which one structural formula is expressed as NH 2 -CH(COOH)-R with an alkyl group R, in water have been measured for 50 years or more. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Lyons and Thomas determined the D 12 values of glycine at two temperatures of (274.2 and 298.2) K. 1 Later, Longsworth measured the D 12 values of glycine, alanine, R-amino-n-butyric acid, norvaline, valine, norleucine, and leucine aqueous solutions at 274.2 K 2 and at 298.2 K. 3 For glycine and alanine aqueous solutions, moreover, the D 12 values over the temperature range from (274.2 to 310.2) K were reported by the same author. 4 At almost the same time, Gutter and Kegeles made the D 12 measurements for an alanine aqueous solution at 298.2 K. 5 Dunlop reported the D 12 values of glycine at 298.2 K. 6 Later, Woolf et al examined the D 12 data for a glycine aqueous solution at 298.2 K. 7 Ellerton et al determined the D 12 values of glycine, R-amino-n-butyric acid, and valine at 298.2 K. 8 Lemaguer et al measured the D 12 values for a glycine aqueous solution at 298.2 K. 9 Chang and Myerson examined the D 12 data of glycine at three temperatures of (298.2, 308.2, and 318.2) K. 10 Paduano et al measured the D 12 values for a norleucine aqueous solution at 298.2 K. 11 Myerson and Lo reported the D 12 data of glycine and valine at 298.2 K. 12 Lu and Leaist measured D 12 values of glycine at 298.2 K. 13 Wu et al 14 and Ma et al 15 Hence, in the present study, the infinite dilution D 12 values for R-amino acids of NH 2 -CH(COOH)-R where R's are alkyl groups up to a butyl group, which are glycine (Gly), alanine (Ala), R-amino-n-butyric acid (Abu), norvaline (Nva), valine (Val), norleucine (Nle), leucine (Leu), isoleucine (Ile), alloisoleucine (aIle), and tert-leucine (t-Leu) in water, were measured over the temperature range from (293.2 to 333.2) K by the Taylor dispersion method.…”

“…Binary diffusion coefficients ( D 12 ) for α-amino acids, of which one structural formula is expressed as NH 2 -CH(COOH)-R with an alkyl group R, in water have been measured for 50 years or more. − Lyons and Thomas determined the D 12 values of glycine at two temperatures of (274.2 and 298.2) K . Later, Longsworth measured the D 12 values of glycine, alanine, α-amino- n -butyric acid, norvaline, valine, norleucine, and leucine aqueous solutions at 274.2 K 2 and at 298.2 K .…”

“…Ellerton et al determined the D 12 values of glycine, α-amino- n -butyric acid, and valine at 298.2 K . Lemaguer et al measured the D 12 values for a glycine aqueous solution at 298.2 K . Chang and Myerson examined the D 12 data of glycine at three temperatures of (298.2, 308.2, and 318.2) K .…”

Binary Diffusion Coefficients of Aqueous Straight-Chain Amino Acids at Infinitesimal Concentration and Temperatures from (298.2 to 333.2) K

“…Measurements of diffusion coefficients for amino acids and their derivatives in aqueous solutions have been reported since at least the late 1930s, at atmospheric pressure and mainly at room temperature, from dilute to concentrated solutions. − Most studies were on α-amino acids, − ,− ,− salts of α-amino acids, , and peptides, ,,,, and other than α-amino acids, β-alanine ,,,, and isomers of aminobutanoic acids have been studied. Almost all studies were on the mutual diffusion coefficients, but some of them were on the self-diffusion coefficients. , …”