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

Abstract

Infinite dilution binary diffusion coefficients (D 12 ) were determined for 10 R-amino acids, glycine, alanine, R-aminon-butyric acid, norvaline, valine, norleucine, leucine, isoleucine, alloisoleucine, and tert-leucine in water over a temperature range from (293.2 to 333.2) K with the Taylor dispersion technique. At 298.2 K, the literature data for the two R-amino acids alloisoleucine and tert-leucine are not available, whereas the determined D 12 values of the others are in good agreement with the data reported previously within the experimental errors of ( 2.0 %. The D 12 values for all R-amino acids studied were well-represented by two simple correlations, and the accuracies for the correlations were examined for each R-amino acid.

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

“…Differences Table 1 Values of D 12 , u, ε and DeSc 1/2 for each ␣-amino acid a ␣-Amino acid in the D 12 values among ␣-amino acids with the same molecular weights were not observed in our previous study [16]. As discussed later, this could result from the much lower hydrophilicity of Hse compared to Thr [21].…”

“…(4) with two adjustable constants α and β accurately represents the measured D 12 data of the ␣-amino acids [16], C5-alcohols [22] and sugars [23] in dilute aqueous solutions, as well as various systems such as organic compounds in supercritical fluids [24], in a mixture of carbon dioxide and hexane [25] and in organic solvents [26] under various pressures:…”

“…The experimental apparatus and procedure were identical with those employed in the previous study [16], and are briefly described below. The degassed water was supplied at a fixed flow velocity of ≈7.0 × 10 −3 m s −1 with a syringe pump (100DM, Isco).…”

“…Recently, we measured the D 12 values of several ␣-amino acids of the NH 2 -CH(COOH)-R form, where R is the alkyl up to a butyl group, in dilute aqueous solutions at temperatures from 293.2 to 333.2 K [16]. In the present study, we focus on ␣-amino acids having a hydroxyl group: serine, Ser (R CH 2 -OH), threonine, Thr [R CH(CH 3 )-OH], its stereoisomer allothreonine, aThr [R CH(CH 3 )-OH] and homoserine, * Corresponding author.…”

Analytical mitigation of solute–capillary interactions in double detection Taylor Dispersion Analysis

“…The diffusion coefficient of injected solutes undergoing Taylor dispersion can be deduced by fitting Taylor's solution to the taylorgrams [27]. Alternatively, this can be achieved by calculating the moments of the profile [3][4][5][6][7][8]12,28,29] or by measuring its height and area [30].…”