Drug−Amino Acid Interactions in Aqueous Medium: Volumetric

Article pubs.acs.org/jced

Drug−Amino Acid Interactions in Aqueous Medium: Volumetric, Compressibility, and Viscometric Studies Suvarcha Chauhan,*,† Kuldeep Singh,† Kuldeep Kumar,† Sundaresan Chittor Neelakantan,‡ and Girish Kumar§ †

Department of Chemistry, Himachal Pradesh University, Summer Hill, Shimla 171005, India Department of Chemistry, Sri Sathya Sai Institute of Higher Learning, Brindavan Campus, Banglore 560067, India § PG Department of Chemistry, JCDAV College, Dasuya 144205, India ‡

S Supporting Information *

ABSTRACT: Density (ρ), speed of sound (u), and viscosity (η) measurements of amino acids L-glutamine and L-histidine in aqueous solutions of metformin hydrochloride (an antidiabetic drug) (0.01, 0.07, and 0.13 mol·kg−1) were carried out in the concentration range (0.02−0.20 mol·kg−1) at 293.15, 298.15, 303.15, 308.15, and 313.15 K. The experimental data has been meticulously used to enumerate various parameters which assist to procure valuable information regarding the presence of different kinds of intermolecular interactions present in the ternary (metformin hydrochloride + water + amino acids) system. The results were interpreted in terms of various metformin hydrochloride−amino acid intermolecular interactions through a cosphere overlap model. The ion−ion interactions are the key players in ternary system and these interactions are of higher order in the case of histidine as compared to glutamine. Also application of transition state theory has been made to calculate the thermodynamic activation parameters for metformin hydrochloride/amino acid mixture solutions. An increase in the entropy of the transition state has been observed which may be due to bond breaking. Furthermore, structure making behavior of both amino acids has been observed in metformin solution. aqueous10,11 solutions have been a subject of interest to understand the physiological action of a drug. However, the drug−protein interactions are somewhat difficult to study because of the complex conformational and configurational three-dimensional structures of protein molecules. Consequently, for a better understanding of drug−protein interactions, the physicochemical properties of amino acids or small peptides as model compounds for proteins are being investigated extensively in aqueous solutions of different types of drugs.12−14 Metformin hydrochloride is an antidiabetic or antihyperglycemic agent that helps to lower both basal and post-prandial elevated blood glucose levels in patients with type II diabetes.15,16 Metformin hydrochloride helps to control glucose

1. INTRODUCTION The drug−macromolecule interactions in aqueous medium are of utmost importance in the biochemical phenomena such as drug transport to the target, binding of drug with proteins, anesthesia, etc. in the physiological, that is, aqueous media.1 Ultimately, the drug−macromolecule interactions affect the action of a drug in the living organism, as it is based on different physiological processes and nature of the receptors for the drug molecules.2 In most of the cases, the receptor molecules for a drug are specialized integral (transmembrane) proteins, which occur freely in different chemical structures, and thus exhibit different physicochemical properties, though the biochemical properties are closely related. Further, on account of amphiphilic groups, the drug molecules show different specific or electrostatic interactions3 and thus can initiate a chain of physicochemical events leading to a pharmacological response.4,5 Therefore, the physicochemical investigations on drug interactions in aqueous,6,7 nonaqueous,8,9 and mixed © XXXX American Chemical Society

Received: July 7, 2015 Accepted: January 14, 2016

A

DOI: 10.1021/acs.jced.5b00549 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

Article

Table 1. Specification of Chemicals Used chemical name

source

CAS No.

MW/(kg·mol−1)

purification method

mass fraction puritya

(C5H10N2O3) (C6H9N3O2) Metformin hydrochloride (C4H11N5−HCl)

Merck Merck Schwitz Biotech

56-85-9 71-00-1

0.146 0.155 0.166

recrystallization recrystallization

> 0.99 > 0.99 > 0.99

L-glutamine L-histidine

a

Declared by the supplier.

temperature (0.01 K) of the viscometer filled with the experimental solutions was obtained by circulating water from a high precision water bath supplied by Narang Scientific Works (NSW) Pvt. Ltd., New Delhi. The efflux time of flow was measured by using a digital stop watch with a precision of 0.01 s. The mean of at least three flow time readings was used as the final efflux time. The standard uncertainty, u (0.068 level of confidence) in viscosity measurements was found to be 0.01 mPa·s.

metabolism in two ways: (i) by decreasing hepatic glucose production and (ii) by decreasing intestinal absorption of glucose. It improves insulin sensitivity by increasing peripheral glucose and does not cause hyperinsulinemia.17 Despite the availability of a good number of thermodynamic studies on the drug interactions in aqueous solutions of additives like surfactants,18,19 electrolytes,20 amino acids, or peptides12,13 etc., the studies on metformin hydrochloride interactions in aqueous solutions of amino acids at different temperatures are scarce.21−23 Therefore, in this study, we report the densities, speeds of sound, and viscosities of two structurally different amino acids L-glutamine (Gln) and L-histidine (His) in aqueous solutions of metformin hydrochloride (Mfm-HCl). Moreover, a wide temperature range (293.15−313.15) K, which also covers our body temperature, that is, 310.15 K, has been chosen for the present study to procure more pertinent information regarding the hydration behavior of these biological important molecules in the presence of metformin hydrochloride.

3. RESULTS AND DISCUSSION 3.1. Volumetric Measurements of L-Glutamine and LHistidine Solutions. The experimental density (ρ) and speed of sound (u) data for L-glutamine and L-histidine in pure water and aqueous solutions of metformin hydrochloride at different temperatures have been summarized in Table 2. The apparent molar volumes (Vφ) for both these amino acids were calculated from density data using following relation: Vϕ =

2. EXPERIMENTAL SECTION 2.1. Materials. The amino acids L-glutamine and L-histidine, both of A.R. grade, were obtained from Merck, Germany, and used after recrystallizations from distilled water. Metformin hydrochloride procured from Schwitz Biotech was analyzed to be 99.66% pure by chromatography and used as such without any pretreatment. The deionized distilled water having conductivity (2−3) μS·cm−1 and pH 6.8−7.0 at T = 298.15 K was obtained from a Millipore-Elix system and used for all experiments. The provenance and purity of chemicals used have also been provided in Table 1. 2.2. Methods. Stock solutions of metformin hydrochloride (0.01, 0.07, and 0.13) mol·kg−1 were prepared in distilled water and were used as solvents for the preparation of amino acid solutions. The required concentrations of L-glutamine and Lhistidine (0.02−0.20 mol·kg−1) were obtained by adding small aliquots of a concentrated amino acid solution to 20 mL of metformin hydrochloride stock solutions. The solutions so prepared were gently stirred on a magnetic stirrer before being subjected to measurements. A balance (Shimadzu) with a precision of 0.0001 g was used during the preparation of all the solutions. The density and speed of sound values of aqueous Lglutamine and L-histidine solutions in the absence and presence of metformin hydrochloride were measured simultaneously with the instrument DSA-5000 from Anton Paar, Austria. The calibration and working principle of the instrument were explained in our previous study.24 The working frequency for the measurement of speed of sound is ∼3 MHz. The standard uncertainty, u (0.068 level of confidence) in density and speed of sound measurements was estimated as 0.08 kg·m−3 and 0.20 m·s−1, respectively. The viscosity measurements were carried out using a jacketed Ostwald viscometer. However, the viscometer was calibrated before use as reported in the literature.25 The constant

⎡ (ρ − ρ ) ⎤ M o ⎥ −⎢ ρ ⎣⎢ mρρo ⎥⎦

(1)

where M is the molar mass of the amino acid (kg·mol−1), ρo and ρ are the densities of the solvent and solution (kg·m−3), respectively, m is the molality (mol·kg−1) of the experimental solution. The calculated Vφ values are included in Table S2 of the Supporting Information, and found to vary linearly with the concentration of amino acids (Figure 1) at all the experimental conditions. Therefore, the partial molar volumes (Voφ) were obtained by least-squares fitting of Vφ data to the equation:26 Vϕ = V ϕo + Svm

(2)

where the experimental slope, Sv, means the solute−solute interactions and the intercept, Voφ, represents the solute− solvent interactions. The Voφ and Sv values with standard errors have been tabulated in Table S3 of Supporting Information. The Sv values for L-glutamine and L-histidine in all the studied systems are found to be negative, suggesting weak solute− solute interactions.27 The Voφ values of L-glutamine and Lhistidine (within the experimental errors) in pure water at T = 298.15 K, are found to be in good agreement with corresponding literature values as shown in the parentheses28−31 (Table S3). Further investigation of Table S3 insinuates that all the Voφ values are positive for both the investigated amino acids.21 This can be rationalized by the cosphere overlap model developed by Friedman and Krishnan,32 as the properties of the water molecules in the hydration cospheres around amino acid and metformin hydrochloride molecules depend on the nature of their intermolecular interactions. The metformin hydrochloride−amino acid interactions can be classified as21 (1) ion−ion interactions between C 4H11N 5H +/Cl − ions of metformin hydrochloride and COO−/NH3+ ions of amino acids; (2) ion−hydrophobic interactions between ionic groups B

DOI: 10.1021/acs.jced.5b00549 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

Article

Table 2. Density, ρ, and Speed of Sound, u, for L-Glutamine and L-Histidine in Pure Water and Aqueous Solutions of Metformin Hydrochloride at Different Temperatures and Experimental Pressure, p = 0.1 MPaa ρ/kg·m−3

m mol·kg

−1b

293.15 K

d

298.15 K

997.055 998.094 999.147 1000.201 1001.256 1002.315 1003.371 1004.431 1005.494 1006.559 1007.625

d

303.15 K

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20

998.218 999.262 1000.319 1001.379 1002.440 1003.504 1004.568 1005.633 1006.693 1007.765 1008.823

995.651 996.679 997.722 998.771 999.819 1000.868 1001.916 1002.971 1004.023 1005.091 1006.144

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20

998.570 999.553 1000.553 1001.568 1002.599 1003.649 1004.719 1005.813 1006.922 1008.025 1009.157

997.402 998.374 999.361 1000.369 1001.388 1002.429 1003.489 1004.578 1005.668 1006.791 1007.943

995.993 996.948 997.929 998.915 999.922 1000.954 1002.006 1003.084 1004.157 1005.269 1006.428

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20

1000.829 1001.780 1002.747 1003.731 1004.739 1005.761 1006.796 1007.859 1008.928 1010.027 1011.123

999.633 1000.577 1001.539 1002.518 1003.516 1004.524 1005.558 1006.616 1007.692 1008.776 1009.888

998.200 999.128 1000.080 1001.056 1002.046 1003.056 1004.088 1005.138 1006.200 1007.276 1008.378

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20

1003.134 1003.820 1005.033 1005.999 1007.000 1008.019 1009.055 1010.164 1011.316 1012.468 1013.675

1001.905 1002.831 1003.771 1004.721 1005.688 1006.688 1007.697 1008.768 1009.821 1010.936 1012.098

1000.448 1001.350 1002.280 1003.218 1004.178 1005.169 1006.146 1007.156 1008.231 1009.255 1010.341

0.02 0.04 0.06 0.08 0.10 0.12 0.14

999.369 1000.533 1001.696 1002.859 1004.028 1005.193 1006.363

998.178 999.317 1000.460 1001.587 1002.730 1003.870 1005.017

996.746 997.854 998.962 1000.070 1001.180 1002.286 1003.395

d

u/m·s−1 308.15 K

313.15 K

L-Glutamine mMfm‑HCl/mol·kg−1 = d d

293.15 K

0.00c 994.032 992.244 1482.96d 995.051 993.226 1483.95 996.088 994.257 1485.35 997.129 995.294 1486.86 998.171 996.332 1488.42 999.218 997.372 1490.07 1000.265 998.413 1491.77 1001.309 999.457 1493.53 1002.359 1000.499 1495.28 1003.412 1001.561 1497.18 1004.482 1002.601 1498.97 mMfm‑HCl/mol·kg−1 = 0.01 994.369 992.542 1483.30 995.309 993.475 1484.62 996.278 994.421 1486.03 997.255 995.391 1487.55 998.261 996.387 1489.18 999.284 997.379 1491.00 1000.307 998.405 1492.91 1001.361 999.458 1494.84 1002.436 1000.503 1496.95 1003.548 1001.648 1498.99 1004.698 1002.787 1501.25 mMfm‑HCl/mol·kg−1 = 0.07 996.524 994.710 1490.25 997.441 995.624 1491.58 998.392 996.566 1493.01 999.354 997.531 1494.51 1000.340 998.526 1496.08 1001.359 999.527 1497.81 1002.384 1000.548 1499.57 1003.423 1001.587 1501.35 1004.489 1002.655 1503.21 1005.569 1003.738 1505.19 1006.692 1004.859 1507.35 mMfm‑HCl/mol·kg−1 = 0.13 998.785 996.926 1496.33 999.678 997.812 1497.67 1000.589 998.715 1499.07 1001.518 999.629 1500.54 1002.462 1000.581 1502.05 1003.416 1001.512 1503.64 1004.404 1002.478 1505.44 1005.404 1003.489 1507.23 1006.412 1004.532 1508.95 1007.436 1005.566 1510.74 1008.507 1006.601 1512.59 L-Histidine mMfm‑HCl/mol·kg−1 = 0.00 995.102 993.257 1484.44 996.183 994.314 1486.22 997.262 995.368 1487.98 998.340 996.420 1489.73 999.416 997.470 1491.46 1000.492 998.515 1493.18 1001.570 999.558 1494.89

C

298.15 K

303.15 K

308.15 K

313.15 K

1497.06d 1497.98 1499.32 1500.78 1502.29 1503.91 1505.59 1507.28 1508.98 1510.73 1512.64

1509.39d 1510.29 1511.58 1513.00 1514.47 1516.05 1517.65 1519.36 1521.00 1522.68 1524.48

1520.08d 1520.93 1522.19 1523.60 1524.98 1526.51 1528.13 1529.76 1531.38 1533.14 1534.83

1529.19d 1530.00 1531.28 1532.64 1533.99 1535.49 1537.06 1538.63 1540.29 1541.99 1543.65

1497.34 1498.60 1500.01 1501.52 1503.18 1504.87 1506.74 1508.58 1510.76 1512.82 1515.14

1509.68 1510.89 1512.25 1513.75 1515.40 1517.00 1518.78 1520.57 1522.62 1524.59 1526.73

1520.30 1521.52 1522.83 1524.30 1525.74 1527.39 1529.33 1531.17 1533.22 1535.25 1537.29

1529.37 1530.54 1531.87 1533.30 1534.91 1536.61 1538.31 1539.97 1542.05 1543.82 1545.91

1503.88 1505.15 1506.51 1508.06 1509.65 1511.35 1513.11 1514.88 1516.78 1518.78 1520.98

1515.76 1517.00 1518.34 1519.80 1521.33 1522.92 1524.66 1526.44 1528.35 1530.28 1532.39

1526.05 1527.20 1528.53 1530.01 1531.55 1533.18 1534.85 1536.62 1538.36 1540.43 1542.42

1534.81 1535.98 1537.25 1538.67 1540.12 1541.69 1543.26 1544.89 1546.69 1548.68 1550.59

1509.67 1510.94 1512.30 1513.76 1515.35 1517.03 1518.78 1520.50 1522.33 1523.99 1525.99

1521.33 1522.58 1523.87 1525.31 1526.80 1528.35 1529.94 1531.72 1533.39 1535.38 1537.35

1531.34 1532.56 1533.85 1535.18 1536.62 1538.12 1539.74 1541.37 1543.28 1545.09 1546.99

1539.84 1541.02 1542.25 1543.62 1545.00 1546.49 1547.99 1549.49 1551.09 1552.79 1554.87

1498.47 1500.21 1501.94 1503.65 1505.35 1507.03 1508.7

1510.74 1512.41 1514.07 1515.72 1517.35 1518.97 1520.54

1521.35 1522.98 1524.6 1526.21 1527.81 1529.39 1530.98

1530.4 1531.98 1533.55 1535.11 1536.66 1538.19 1539.72

DOI: 10.1021/acs.jced.5b00549 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

Article

Table 2. continued ρ/kg·m−3

m mol·kg

−1b

293.15 K

298.15 K

303.15 K

u/m·s−1 308.15 K

313.15 K −1

0.16 0.18 0.20

1007.531 1008.709 1009.890

1006.164 1007.319 1008.469

1004.503 1005.610 1006.715

0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20

999.640 1000.721 1001.817 1002.921 1004.055 1005.184 1006.328 1007.505 1008.682 1009.887

998.446 999.500 1000.563 1001.658 1002.778 1003.901 1005.055 1006.205 1007.402 1008.578

997.004 998.027 999.068 1000.118 1001.196 1002.269 1003.371 1004.488 1005.648 1006.817

0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20

1001.886 1003.013 1004.182 1005.392 1006.664 1007.998 1009.445 1010.876 1012.402 1013.895

1000.653 1001.706 1002.844 1003.966 1005.138 1006.391 1007.621 1008.896 1010.266 1011.708

999.188 1000.206 1001.257 1002.326 1003.455 1004.604 1005.779 1006.987 1008.216 1009.532

0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20

1004.000 1004.920 1005.897 1006.965 1008.038 1009.202 1010.457 1011.738 1013.093 1014.526

1002.740 1003.626 1004.550 1005.518 1006.557 1007.628 1008.794 1009.988 1011.309 1012.703

1001.238 1002.058 1002.922 1003.797 1004.729 1005.669 1006.656 1007.717 1008.821 1009.883

293.15 K

mMfm‑HCl/mol·kg = 1002.644 1000.598 1003.719 1001.632 1004.781 1002.666 mMfm‑HCl/mol·kg−1 = 995.347 993.498 996.350 994.478 997.370 995.478 998.409 996.482 999.459 997.517 1000.538 998.583 1001.613 999.651 1002.735 1000.789 1003.838 1001.937 1005.009 1003.104 mMfm‑HCl/mol·kg−1 = 997.472 995.622 998.457 996.562 999.472 997.530 1000.518 998.496 1001.569 999.491 1002.657 1000.485 1003.796 1001.466 1004.959 1002.498 1006.104 1003.525 1007.257 1004.605 mMfm‑HCl/mol·kg−1 = 999.540 997.659 1000.321 998.418 1001.138 999.199 1001.988 1000.008 1002.843 1000.849 1003.757 1001.698 1004.689 1002.608 1005.624 1003.543 1006.588 1004.477 1007.582 1005.437

0.00 1496.56 1498.23 1499.86 0.01 1485.09 1486.87 1488.65 1490.42 1492.18 1493.94 1495.70 1497.45 1499.21 1500.91 0.07 1491.95 1493.62 1495.32 1496.99 1498.65 1500.37 1502.01 1503.83 1505.60 1507.46 0.13 1497.97 1499.61 1501.24 1502.83 1504.58 1506.38 1507.87 1509.62 1511.37 1513.07

298.15 K

303.15 K

308.15 K

313.15 K

1510.34 1511.96 1513.58

1522.15 1523.73 1525.32

1532.51 1534.08 1535.6

1541.23 1542.74 1544.25

1499.09 1500.83 1502.56 1504.28 1505.98 1507.70 1509.37 1511.08 1512.75 1514.47

1511.32 1512.96 1514.60 1516.25 1517.88 1519.54 1521.17 1522.80 1524.38 1525.98

1521.87 1523.44 1525.02 1526.62 1528.22 1529.78 1531.36 1532.91 1534.59 1536.12

1530.87 1532.38 1533.90 1535.40 1536.97 1538.47 1539.96 1541.48 1542.96 1544.48

1505.49 1507.13 1508.71 1510.22 1511.81 1513.42 1515.13 1517.03 1518.59 1520.13

1517.25 1518.78 1520.30 1521.81 1523.37 1524.90 1526.55 1528.30 1529.96 1531.53

1527.47 1528.92 1530.40 1531.78 1533.38 1534.84 1536.41 1538.07 1539.58 1541.32

1536.16 1537.53 1538.92 1540.37 1541.83 1543.24 1544.76 1546.32 1547.84 1549.62

1511.21 1512.80 1514.43 1516.10 1517.79 1519.49 1521.09 1522.94 1524.58 1526.39

1522.75 1524.21 1525.69 1527.21 1528.66 1530.32 1531.91 1533.45 1535.12 1536.78

1532.69 1534.10 1535.49 1536.93 1538.48 1539.79 1541.47 1542.95 1544.98 1546.79

1541.11 1542.42 1543.75 1545.02 1546.41 1547.87 1549.32 1550.79 1552.30 1554.00

Standard uncertainties, u, are u(T) = 0.01 K, u(p) = 0.002 MPa, u(ma) = 0.002 mol·kg−1, u(mb) = ± 0.003 mol·kg−1, u (ρ) = 0.08 kg·m−3, and u (u) = 0.2 m·s−1 (level of confidence =0.68). bm is the molality of amino acid in water and water + metformin−hydrochloride solvent systems. cm is the molality of metformin hydrochloride in water. dReference 24. a

and consequently results in increase in ΔtrVoφ values. However, as the temperature increases, the release of some water molecules from the loose hydration layers of amino acids into the bulk of solution may take place followed by the strengthening of ion−ion interactions and volume expansion.33 Comparatively, the ΔtrVoφ values are higher in magnitude for Lhistidine than that of L-glutamine at all experimental conditions (Table S3). It may be due to the more dominating nature of type (1) interactions in the case of L-histidine as a consequence of the presence of extra positive charge on its imidazole ring in aqueous solutions.34 3.2. Compressibility Measurements of L-Glutamine and L-Histidine Solutions. The apparent molar isentropic compression (κs,φ) values for L-glutamine and L-histidine were calculated using the relation,

of metformin hydrochloride/amino acids and the nonpolar groups of amino acids/metformin hydrochloride; (3) hydrophobic−hydrophobic interactions between the nonpolar groups of metformin hydrochloride and nonploar side chain of amino acids. In accordance with the cosphere overlap model,32 the observed positive Voφ and ΔtrVoφ (Table S3 of Supporting Information) values can be related to the predominance of the above said interactions of type (1) over the interactions of types (2) and (3). The interactions of type (1) are considered to be responsible for diminishing the electrostriction of the water molecules in the proximity of zwitter ionic centers of the amino acids, which lead to a positive volume contribution.22 A pronounced increase in ΔtrVoφ values (Table S3) has been noticed with concentration of metformin hydrochloride and temperature as well. The increase in concentration of drug may add to greater extent of ion−ion interactions as compared to ion−hydrophobic or hydrophobic−hydrophobic interactions

⎡ (κs − κs,o) ⎤ ⎥ + κsVϕ κs, ϕ = ⎢ ⎢⎣ ⎥⎦ mρo D

(3) DOI: 10.1021/acs.jced.5b00549 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

Article

Figure 1. Representative plots of Vφ versus concentration for (a) Lglutamine and (b) L-histidine in 0.13 mol·kg−1 aqueous solution of metformin hydrochloride at 293.15 K (■), 298.15 K (●), 303.15 K (▲), 308.15 K (▼), and 313.15 K (◀).

Figure 2. Representative plots of κs versus concentration of (a) Lglutamine and (b) L-histidine in 0.13 mol·kg−1 aqueous solution of metformin hydrochloride at 293.15 K (■), 298.15 K (●), 303.15 K (▲), 308.15 K (▼), and 313.15 K (◀).

where κs and κs,o are the isentropic compressibilities of the solution and solvent (TPa−1), respectively, and can be calculated according to the relations S2 and S3 in Supporting Information. The κs data have been reported in Table S5 of the Supporting Information and illustrated graphically in Figure 2. The κs values decrease with molal concentration of both the amino acids and temperature as well (Figure 3), in aqueous metformin hydrochloride solutions. Similar types of trends have also been reported in the literature for amino acid, 4aminobutyric acid in aqueous solutions of metformin hydrochloride.23 This decrease in κs may be attributed to an increase in the number of incompressible molecules or ions, and formation of zwitterions−water dipoles and zwitterions−ions compact structures in solutions.23 Though, the temperature effect on isentropic compressibility may be due to rupture of water structure around the zwitterions of amino acids and hydrophilic groups of metformin hydrochloride, which results in the strengthening of ion−ion interactions. In addition, the κs values for L-histidine in all the solvent systems are found to be higher in magnitude than L-glutamine, suggesting stronger

metformin hydrochloride− L-histidine interactions as explained by volumetric parameters. The κs,φ values have been recorded in Table S2 of the Supporting Information. The linear variation of κs,φ with molalities of amino acids (Figure 3) helps to compute the partial molar isentropic compressions (κos,φ) and slopes (Sk) by using method of linear regression of following relation: κs, ϕ = κs,oϕ + Skm

(4) o κs,φ ,

where the intercept, measures the solute−solvent interactions and the slope, Sk, affords information regarding solute−solute interactions. Thus, obtained κos,φ values were employed to calculate the o ) partial molar isentropic compression of transfer (Δtrκs,φ (equation S4 in Supporting Information) of amino acids from water to aqueous metformin hydrochloride solutions and are included in the Supporting Information. To best of our knowledge, no compressibility data of these amino acids in pure water is available in the literature for comparison purposes. The negative κos,φ values (Table S3) E

DOI: 10.1021/acs.jced.5b00549 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

Article

The viscosity data have been analyzed in terms of A- and Bcoefficients of viscosity using the Jones−Dole equation37 of the form ψ = (ηr − 1)/m1/2 = A + Bm1/2

(5)

where ηr(=η/ηo) is the relative viscosity of the solution, η and ηo are the viscosities of solution and the solvent, respectively, and m is molality of amino acids. The Falkenhagen coefficient, A, accounts for the solute−solute interactions, while the Jones− Dole coefficient, B, is a measure of structural modifications induced by the solute−solvent interactions.37,38 The intercepts and slopes of linear regression of ψ vs m1/2 plots (Figure 4) give the values of A- and B-coefficients, respectively. The values of A- and B-coefficients for L-histidine and L-glutamine in all the cases have been reported in Table S6. The A-coefficients are found to be negligible (i.e., close to zero) indicating weak solute−solute interactions.39 The positive Bcoefficients (Table S6) for both the amino acids are indicative of kosmotropes,40 since amino acids are the strongly hydrated solutes and, therefore, exhibit a larger change in the viscosity of the solution with concentration. Thus, the B-coefficients in all cases are suggesting strong solute−solvent interactions. The solute−solvent interactions seem to be more effective in the presence of L-histidine as reflected by its higher B-coefficients compared to those in L-glutamine. Furthermore, from Table S6, the decrease in the B-coefficients with rise in temperature, that is, negative dB/dT values shows the structure promoting tendency of L-histidine and L-glutamine. Thus, the dB/dT values are complementing the conclusions drawn from the discussion of the Hepler’s constants in the Supporting Information. Also, the Eyring transition theory was applied for the system to calculate some activation parameters such as free energy of activation of viscous flow per mole of solvent (Δμo1*), the free energy of activation of viscous flow per mole of solute (Δμo2*), the activation entropy (ΔSo2*), and activation enthalpy (ΔHo2*) for viscous flow, which are found to be of immense value in order to understand the different intermolecular interactions present in the system.41 These calculated parameters have been included in the Supporting Information. The V1o , Δμo1*, and Δμo2* data have been summarized in Table S7 of the Supporting Information. After examination of Table S7, it is evident that for both the amino acids Δμo2* values are positive and much larger than those of Δμo1* values. This suggests that the interactions between amino acids and solvent (aqueous metformin hydrochloride) molecules in the ground state are stronger than in the transition state. Consequently, the formation of the transition state is less favored in terms of energy due to breaking or distortion of the intermolecular bonds.42 It is interesting to note that Δμo2* values also show dependence on the type of amino acid; greater values have been observed for L-histidine as compared to Lglutamine. Further, the Δμo2* values follow an irregular trend with regards to temperature; however, these values increase as the concentration of metformin hydrochloride increases from (0.01 to 0.13) mol·kg−1, indicate the strengthening of metformin hydrochloride-amino acid interactions, and making the flow of solute molecules difficult.43 Also the values of TΔSo2* and ΔHo2* at different temperatures are recorded in Table S7. It is interesting to note that for both the amino acids, the ΔHo2* and TΔSo2* values are positive. This occurs because the attainment of the transition state for viscous

Figure 3. Representative plots of κs,φ versus concentration of (a) Lglutamine and (b) L-histidine in 0.13 mol·kg−1 aqueous solution of metformin hydrochloride at 293.15 K (■), 298.15 K (●), 303.15 K (▲), 308.15 K (▼), and 313.15 K (◀).

showing the presence of strong solute−solvent interactions result in less compressible solutions.35 A significant rise in κos,φ values with concentration of metformin hydrochloride and temperature indicates the strengthening of metformin hydrochloride−amino acid interactions due to a release of large water molecules from a secondary solvation layer of zwitterionic centers of amino acids into the bulk of water, which makes the solutions more compressible. Similar observation has been made by others36 for some amino acids in dilute aqueous solutions. Also, the relatively smaller negative Sk values (except for L-histidine in pure water) (Table S3) for both the amino acids at all concentrations of metformin hydrochloride, suggest very weak solute−solute interactions. All these results derived from the compressibility studies are in accordance with the results of the volumetric measurements. 3.3. Viscometric Measurements of L-Histidine and LGlutamine Solutions. The experimental viscosity (η) values for L-glutamine and L-histidine in pure water and aqueous solutions of metformin hydrochloride at different temperatures have been listed in Table 3. F

DOI: 10.1021/acs.jced.5b00549 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

Article

Table 3. Viscosity, η, for L-Glutamine and L-Histidine in Pure Water and Aqueous Solutions of Metformin Hydrochloride at Different Temperatures and Experimental Pressure, p = 0.1 MPaa η/mPa·s m mol·kg−1b

L-glutamine

293.15 K

298.15 K

303.15 K

L-histidine

308.15 K

313.15 K −1

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20

1.0019d 1.0116 1.0175 1.0221 1.0267 1.0310 1.0349 1.0389 1.0432 1.0472 1.0512

0.8903d 0.8984 0.9028 0.9067 0.9104 0.9143 0.9175 0.9212 0.9246 0.9277 0.9308

0.7973d 0.8039 0.8076 0.8109 0.8141 0.8170 0.8200 0.8224 0.8254 0.8283 0.8316

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20

1.0099 1.0174 1.0220 1.0260 1.0301 1.0340 1.0379 1.0415 1.0455 1.0487 1.0519

0.8925 0.8983 0.9021 0.9057 0.9088 0.9121 0.9149 0.9179 0.9210 0.9242 0.9273

0.8013 0.8062 0.8093 0.8121 0.8149 0.8178 0.8202 0.8229 0.8257 0.8280 0.8305

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20

1.0152 1.0234 1.0281 1.0327 1.0371 1.0409 1.0450 1.0491 1.0533 1.0566 1.0605

0.8990 0.9055 0.9094 0.9131 0.9167 0.9203 0.9231 0.9260 0.9298 0.9334 0.9368

0.8074 0.8124 0.8157 0.8191 0.8219 0.8251 0.8278 0.8302 0.8326 0.8352 0.8382

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20

1.0185 1.0269 1.0317 1.0361 1.0406 1.0443 1.0488 1.0528 1.0568 1.0607 1.0654

0.9052 0.9119 0.9159 0.9197 0.9237 0.9269 0.9307 0.9337 0.9372 0.9405 0.9441

0.8126 0.8180 0.8213 0.8244 0.8276 0.8305 0.8336 0.8360 0.8387 0.8419 0.8450

293.15 K

298.15 K

303.15 K

308.15 K

313.15 K

0.8903d 0.8996 0.9048 0.9091 0.9138 0.9175 0.9222 0.9259 0.9293 0.9336 0.9374

0.7973d 0.8051 0.8093 0.8130 0.8165 0.8198 0.8233 0.8265 0.8301 0.8339 0.8372

0.7190d 0.7253 0.7289 0.7320 0.7348 0.7378 0.7407 0.7435 0.7466 0.7492 0.7524

0.6526d 0.6578 0.6608 0.6633 0.6660 0.6682 0.6709 0.6734 0.6756 0.6783 0.6810

0.8925 0.9001 0.9047 0.9087 0.9126 0.9166 0.9200 0.9238 0.9276 0.9321 0.9357

0.8013 0.8063 0.8095 0.8128 0.8159 0.8188 0.8219 0.8252 0.8279 0.8303 0.8335

0.7245 0.7278 0.7304 0.7332 0.7356 0.7383 0.7405 0.7429 0.7449 0.7470 0.7497

0.6566 0.6608 0.6633 0.6657 0.6680 0.6707 0.6729 0.6752 0.6775 0.6801 0.6827

0.8990 0.9060 0.9104 0.9146 0.9188 0.9223 0.9260 0.9299 0.9338 0.9368 0.9408

0.8074 0.8133 0.8166 0.8200 0.8233 0.8270 0.8299 0.8330 0.8357 0.8394 0.8428

0.7285 0.7334 0.7363 0.7391 0.7420 0.7447 0.7478 0.7500 0.7530 0.7560 0.7587

0.6606 0.6650 0.6674 0.6700 0.6725 0.6751 0.6772 0.6795 0.6823 0.6847 0.6873

0.9052 0.9129 0.9172 0.9209 0.9248 0.9287 0.9327 0.9368 0.9415 0.9453 0.9493

0.8126 0.8192 0.8232 0.8269 0.8302 0.8335 0.8366 0.8403 0.8440 0.8477 0.8512

0.7333 0.7384 0.7417 0.7445 0.7473 0.7499 0.7527 0.7558 0.7594 0.7621 0.7647

0.6662 0.6701 0.6729 0.6753 0.6775 0.6798 0.6825 0.6849 0.6873 0.6897 0.6921

c

mMfm‑HCl/mol·kg = 0.00 0.7190d 0.6526d 1.0019d 0.7243 0.6569 1.0132 0.7275 0.6595 1.0194 0.7302 0.6621 1.0250 0.7329 0.6638 1.0301 0.7352 0.6660 1.0349 0.7379 0.6682 1.0403 0.7405 0.6702 1.0446 0.7425 0.6716 1.0491 0.7448 0.6740 1.0540 0.7469 0.6759 1.0581 mMfm‑HCl/mol·kg−1 = 0.01 0.7245 0.6566 1.0099 0.7286 0.6600 1.0184 0.7312 0.6624 1.0235 0.7337 0.6645 1.0284 0.7361 0.6665 1.0327 0.7387 0.6685 1.0369 0.7409 0.6707 1.0405 0.7430 0.6726 1.0459 0.7447 0.6744 1.0500 0.7471 0.6762 1.0546 0.7497 0.6778 1.0588 mMfm‑HCl/mol·kg−1 = 0.07 0.7285 0.6606 1.0152 0.7324 0.6637 1.0242 0.7352 0.6658 1.0298 0.7378 0.6682 1.0350 0.7402 0.6699 1.0400 0.7427 0.6720 1.0446 0.7450 0.6739 1.0494 0.7472 0.6756 1.0537 0.7493 0.6777 1.0578 0.7518 0.6796 1.0622 0.7537 0.6819 1.0668 mMfm‑HCl/mol·kg−1 = 0.13 0.7333 0.6662 1.0185 0.7375 0.6696 1.0280 0.7405 0.6721 1.0331 0.7431 0.6743 1.0377 0.7457 0.6767 1.0425 0.7484 0.6786 1.0470 0.7509 0.6808 1.0518 0.7533 0.6829 1.0572 0.7554 0.6844 1.0617 0.7576 0.6867 1.0664 0.7598 0.6889 1.0714

Standard uncertainties, u, are u(T) = 0.01 K, u(p) = 0.002 MPa, u(ma) = 0.002 mol·kg−1, u(mb) = 0.003 mol·kg−1, and u(η) = 0.01 mPa·s (level of confidence = 0.68). bm is the molality of amino acid in water and water + metformin hydrochloride solvent systems. cm is the molality of metformin hydrochloride in water. dReference 38. a

flow is related to bond breaking and decrease in order in the present ternary systems.43 The ΔHo2* data reveal that the formation of activated species for viscous flow becomes more difficult in the case of L-histidine as compared to L-glutamine. Moreover, the L-histidine−metformin hydrochloride aqueous

system is more ordered than the

L-glutamine−metformin

hydrochloride aqueous system as pointed out by the TΔSo2* values (Table S7). G

DOI: 10.1021/acs.jced.5b00549 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

■

Article

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jced.5b00549. Densities and speeds of sound of pure liquids with literature values, apparent molar volume, apparent molar isentropic compression, standard partial molar volume, standard partial molar isentropic compression, and transfer values of partial molar volume and partial molar isentropic compression, values of coefficients, a, b, and c, of equation (S5) partial molar expansion coefficients, Hepler’s constant, isentropic compressibility, Falkehagen coefficient, Jone’s Dole coefficient and its transfer values, mean volume of solvent, free energy of activation of viscous flow per mole of solvent, free energy of activation of viscous flow per mole of solute, entropy of activation of viscous flow and enthalpy of activation of viscous flow for amino acids in aqueous metformin hydrochloride solutions at different temperatures (PDF)

■

AUTHOR INFORMATION

Corresponding Author

*Tel.: +91 177 2830803. Fax: +91 177 2830775. E-mail: [email protected]. Funding

Suvarcha Chauhan and Kuldeep Kumar thank UGC New Delhi for the financial assistance under the project (F. No. 42−249/ 2013/SR) and basic scientific research fellowship (F. No. 7− 75/2007/BSR), respectively. Notes

The authors declare no competing financial interest.

■

REFERENCES

(1) Singla, M.; Jindal, R.; Kumar, H. Volumetric, acoustic, and UV absorption studies on solute−solvent interactions of dipeptides of glycine with aqueous amoxicillin solutions. Thermochim. Acta 2014, 591, 140−151. (2) King, F. D. Medicinal Chemistry, Principles and Practices; The Royal Society of Chemistry: United Kingdom Cambridge, 1984. (3) Sharma, P.; Chauhan, S. Studies of partial Molar Volumes of Some Narcotic-Analgesic Drugs in Aqueous-Alcoholic Mixtures at 25◦C. Int. J. Thermophys. 2008, 29, 643−655. (4) Sadavongvivad, C. Receptor theory of drug action. J. Sci. Soc. Thailand 1972, 3, 61−72. (5) Ahluwalia, V. K.; Chopra, M. Medicinal Chemistry; Ane Books: New Delhi, India, 2008 (6) Dhondge, S. S.; Zodape, S. P.; Parwate, D. V. Volumetric and viscometric studies of some drugs in aqueous solutions at different temperatures. J. Chem. Thermodyn. 2012, 48, 207−212. (7) Chadha, R.; Kashid, N.; Jain, D. V. S. Microcalorimetric studies to determine the enthalpy of solution of diclofenac sodium, paracetamol and their binary mixtures at 310.15 K. J. Pharm. Biomed. Anal. 2003, 30, 1515−1522. (8) Domanska, U.; Pobudkowska, A.; Pelczarska, A.; Gierycz, P. pKa and solubility of drugs in water, ethanol, and 1-octanol. J. Phys. Chem. B 2009, 113, 8941−8947. (9) Iqbal, M. J.; Chaudhry, M. A. Effect of temperature on volumetric and viscometric properties of some non-steroidal anti-inflammatory drugs in aprotic solvents. J. Chem. Thermodyn. 2010, 42, 951−956. (10) Bhardwaj, V.; Sharma, P.; Chauhan, M. S.; Chauhan, S. Thermodynamic, FTIR, 1H-NMR, and acoustic studies of butylated hydroxyanisole and sodium dodecyl sulfate in ethanol, water rich and ethanol rich solutions. J. Mol. Liq. 2013, 180, 192−199.

Figure 4. Representative plots of Ψ versus m1/2 (a) L-glutamine and (b) L-histidine in 0.13 mol·kg−1 aqueous solution of metformin hydrochloride at 293.15 K (■), 298.15 K (●), 303.15 K (▲), 308.15 K (▼), and 313.15 K (◀).

4. CONCLUSIONS The general outcome drawn from the discussed different techniques is that ionic/electrostatic interactions are playing the major role for both of the investigated amino acids in aqueous solutions of metformin hydrochloride which get further strengthened with increase in metformin hydrochloride concentration, ionic character of amino acids, and temperature as well. The variation of expansion coefficients with temperature is indicative of a different hydration behavior of these amino acids as compared to that of common electrolytes. The positive values of Hepler’s constant have been argued for the structure−making behavior of these amino acids in aqueous metformin hydrochloride solutions, which is further substantiated by their negative dB/dT values. The Δμo2* values are revealing in that the formation of transition state is less favored in terms of energy for the present ternary systems. Moreover, the attainment of the transition state is accompanied by bond breaking and decrease in order as confirmed by the positive ΔHo2* and TΔSo2* values, respectively. H

DOI: 10.1021/acs.jced.5b00549 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

Article

(11) Rajagopal, K.; Jayabalkrishnan, S. S. Volumetric, ultrasonic speed, and viscometric studies of salbutamol sulphate in aqueous methanol solution at different temperatures. J. Chem. Thermodyn. 2010, 42, 984−993. (12) Chauhan, S.; Chaudhary, P.; Sharma, K.; Kumar, K.; Kiran. Temperature-dependent volumetric and viscometric properties of amino acids in aqueous solutions of an antibiotic drug. Chem. Pap. 2013, 67, 1442−1452. (13) Pal, A.; Chauhan, N. Interactions of amino acids and peptides with the drug pentoxifylline in aqueous solution at various temperatures: A volumetric approach. J. Chem. Thermodyn. 2012, 54, 288− 292. (14) Kumar, H.; Kaur, K. Interaction of antibacterial drug ampicillin with glycine and its dipeptides analyzed by volumetric and acoustic methods at different temperatures. Thermochim. Acta 2013, 551, 40− 45. (15) Corti, G.; Cirri, M.; Maestrelli, F.; Mennini, N.; Mura, P. Sustained−release matrix tablets of metformin hydrochloride in combination with triacetyl-β-cyclodextrin. Eur. J. Pharm. Biopharm. 2008, 68, 303−309. (16) Hu, L. D.; Liu, Y.; Tang, X.; Zhang, Q. Preparation and in vitro/ in vivo evaluation of sustained-release metformin hydrochloride pellets. Eur. J. Pharm. Biopharm. 2006, 64, 185−192. (17) Harahap, Y.; Purnasari, S.; Hayun; Dianpratami, K.; Wulandari, M.; Rahmawati, R.; Chany, F.; Senjaya, R. N. Bioequivalence study of metformin HCl XR caplet formulations in healthy Indonesian volunteers. J. Bioequivalence Bioavailability 2011, 3, 16−19. (18) Kaushal, D.; Rana, D. S.; Chauhan, M. S.; Umar, A.; Chauhan, S. The effect of sodiumdodecyl sulphate on furosemide−a cardiovascular drug in water−methanol at different temperature. J. Mol. Liq. 2013, 188, 237−244. (19) Chauhan, S.; Chauhan, M. S.; Kaushal, D.; Syal, V. K.; Jyoti, J. Study of micellar behavior of SDS and CTAB in aqueous media containing furosemide−a cardiovascular drug. J. Solution Chem. 2010, 39, 622−638. (20) Banipal, T. S.; Singh, H.; Banipal, P. K. Volumetric and viscometric properties of some sulpha drugs in aqueous solutions of sodium chloride at T= (288.15 to 318.15) K. J. Chem. Eng. Data 2010, 55, 3872−3881. (21) Rajagopal, K.; Jayabalakrishnan, S. S. Effect of temperature on volumetric and viscometric properties of homologous amino acids in aqueous solutions of metformin hydrochloride. Chin. J. Chem. Eng. 2010, 18, 425−445. (22) Rajagopal, K.; Jayabalakrishnan, S. S. A volumetric and viscometric study of 4-aminobutyric acid in aqueous solutions of metformin hydrochloride at 308.15, 313.15 and 318.15 K. J. Serb. Chem. Soc. 2011, 76, 129−142. (23) Rajagopal, K.; Jayabalakrishnan, S. S. Ultrasonic studies of 4− aminobutyric acid in aqueous metformin hydrochloride solutions at different temperatures. Int. J. Thermophys. 2010, 31, 2225−2238. (24) Kumar, K.; Chauhan, S. Volumetric, compressibility and viscometric studies on sodium cholate/sodium deoxycholate−amino acid interactions in aqueous medium. Thermochim. Acta 2015, 606, 12−24. (25) Kumar, K.; Patial, B. S.; Chauhan, S. Interactions of saccharides in aqueous glycine and leucine solutions at different temperatures of (293.15 to 313.15) K: a viscometric study. J. Chem. Eng. Data 2015, 60, 47−56. (26) Romero, C. M.; Negrete, F. Effect of temperature on partial molar volumes and viscosities of aqueous solutions of α−DL− aminobutyric acid, DL−norvaline and DL−norleucine. Phys. Chem. Liq. 2004, 42, 261−267. (27) Pal, A.; Soni, S. Volumetric approach to the interaction of diglycine in aqueous solutions of sulpha drugs at T = 288.15−308.15 K. Fluid Phase Equilib. 2012, 334, 144−151. (28) Natarajan, M.; Wadi, R. K.; Gaur, H. C. Apparent molar volumes and viscosities of some α− and α,ω−amino acids in aqueous ammonium chloride solutions at 298.15 K. J. Chem. Eng. Data 1990, 35, 87−93.

(29) Yuan, Q.; Li, Z. F.; Wang, B. H. Partial molar volumes of L− alanine, DL−serine, DL−threonine L-histidine, glycine, and glycylglycine in water, NaCl, and DMSO aqueous solutions at T = 298.15 K. J. Chem. Thermodyn. 2006, 38, 20−33. (30) Rajagopal, K.; Johnson, J. Studies in volumetric and viscometric properties of L-histidine in aqueous solutions of xylose solution over temperature range (298.15 to 313.15) K. Int. J. Chem. Tech Res. 2015, 8, 346−355. (31) Zhao, H. Viscosity B− coefficient and standard partial molar volumes of amino acids, and their roles in interpreting the protein (enzyme) stabilization. Biophys. Chem. 2006, 122, 157−183. (32) FriedMan, H.; Krishnan, C. V. Water: A Comprehensive Treatise; Plenum Press, New York. 1973. (33) Rajagopal, K.; Gladson, S. E. Partial molar volume and partial molar compressibility of four homologous α−amino acids in aqueous sodium fluoride solutions at different temperatures. J. Chem. Thermodyn. 2011, 43, 852−867. (34) Kumar, K.; Patial, B. S.; Chauhan, S. Conductivity and fluorescence studies on the micellization properties of sodium cholate and sodium deoxycholate in aqueous medium at different temperatures: effect of selected amino acids. J. Chem. Thermodyn. 2015, 82, 25−33. (35) Chauhan, S.; Kumar, K. Effect of glycine on aqueous solution behavior of saccharides at different temperatures: volumetric and ultrasonic studies. J. Mol. Liq. 2014, 194, 212−226. (36) Kikuchi, M.; Sakurai, M.; Nitta, K. Partial molar volumes and adiabatic compressibilities of amino acids in dilute aqueous solutions at 5, 15, 25, 35, and 45 °C. J. Chem. Eng. Data 1996, 40, 935−942. (37) Jones, G.; Dole, M. The viscosity of Aqueous Solutions of Strong Electrolytes with Special Reference to Barium Chloride. J. Am. Chem. Soc. 1929, 51, 2950−2964. (38) Chauhan, S.; Kumar, K.; Chauhan, M. S.; Rana, D. S.; Umar, A. Acoustical and volumetric studies of proline in ethanolic solutions of lecithin at different temperatures. Adv. Sci., Eng. Med. 2013, 5, 991− 997. (39) Feakins, D.; Freemantle, D. J.; Lawrence, K. G. Transition state treatment of the relative viscosity of electrolytic solutions. Applications to aqueous, non−aqueous and methanol + water systems. J. Chem. Soc., Faraday Trans. 1 1974, 70, 795−806. (40) Iqbal, M. J.; Chaudhry, M. A. Thermodynamic study of three pharmacologically significant drugs: Density, viscosity, and refractive index measurements at different temperatures. J. Chem. Thermodyn. 2009, 41, 221−226. (41) Chauhan, S.; Kumar, K. Partial molar volumes and isentropic compressibilities of some saccharides in aqueous solutions of leucine at different temperatures. J. Chem. Eng. Data 2014, 59, 1375−1384. (42) Pal, A.; Kumar, S. Viscometric and volumetric studies of some amino acids in binary aqueous solutions of urea at various temperatures. J. Mol. Liq. 2004, 109, 23−31. (43) Nain, A. K.; Lather, M.; Sharma, R. K. Volumetric, ultrasonic and viscometric behavior of L−methionine in aqueous−glucose solutions at different temperatures. J. Mol. Liq. 2011, 159, 180−188.

I

DOI: 10.1021/acs.jced.5b00549 J. Chem. Eng. Data XXXX, XXX, XXX−XXX