Heat capacities of monomer models of some hydrophilic polymers in an aqueous solution from 20° to 60 °C

1982 ◽  
Vol 47 (10) ◽  
pp. 2692-2701 ◽  
Author(s):  
Ján Biroš ◽  
Antonín Sikora ◽  
Antonín Živný ◽  
Julius Pouchlý
Keyword(s):  
Aqueous Solution ◽  
Heat Capacities ◽  
Hydrophilic Polymers ◽  
The Other ◽  
Bulk Liquid ◽  
Apparent Molar Heat Capacities ◽  
Apparent Heat Capacity ◽  
Dilute Aqueous Solution ◽  
Specific Volumes ◽  
Good Agreement

The apparent molar heat capacities of propionic and isobutyric acids and of 2-hydroxyethyl pivalate and 2-(2'-hydroxyethoxy)ethyl pivalate in a dilute aqueous solution were determined with a DASM-1 m calorimeter. Moreover, the apparent specific volumes of these compounds in the aqueous solution and their molar heat capacities in the bulk liquid state were also determined. In the range 20° - 60 °C the apparent heat capacity in the aqueous solution is temperature-independent, or (in the case of propionic acid) increases slightly with temperature. The apparent heat capacities measured at 25 °C were compared with values estimated using various reported additivity schemes. Good agreement was observed for both acids; the other two compounds with more complicated molecules showed significant deviations from additivity.

scholarly journals Green quantitative spectrofluorometric analysis of rupatadine and montelukast at nanogram scale using direct and synchronous techniques

2021 ◽  
Vol 8 (11) ◽  
Author(s):  
Rana Ghonim ◽  
Mohamed I. El-Awady ◽  
Manar M. Tolba ◽  
Fawzia Ibrahim
Keyword(s):  
Aqueous Solution ◽  
Sodium Dodecyl Sulfate ◽  
Sodium Dodecyl ◽  
Comparison Method ◽  
Assessment Tools ◽  
The Other ◽  
Statistical Interpretation ◽  
First Derivative ◽  
Ich Guidelines ◽  
Good Agreement

Two green-sensitive spectrofluorometric methods were investigated for assay of rupatadine (RUP) [method I] and its binary mixture with montelukast (MKT) [method II]. Method I depends on measuring native fluorescence of RUP in the presence of 0.10 M H 2 SO 4 and 0.10%w/v sodium dodecyl sulfate at 455 nm after excitation at 277 nm. The range of the first method was 0.20–2.00 µg ml −1 with detection and quantitation limits of 59.00 and 179.00 ng ml −1 , respectively. Method II depends on the first derivative synchronous spectrofluorometry. The derivative intensities were measured for the two drugs in an aqueous solution containing Mcllvaine's buffer pH 2.60 at fixed Δ λ of 140 nm. Each drug was estimated at zero-contribution of the other. The intensity was measured at 261 and 371 nm for RUP and MKT, respectively. The method was linear over 0.10–4.00 and 0.20–1.60 µg ml −1 with limits of detection 31.00 and 66.00 ng ml −1 and limits of quantitation 94.00 and 200.00 ng ml −1 for RUP and MKT, respectively. The method was extended to determine this mixture in laboratory-prepared mixtures and combined tablets. Method validation was performed according to ICH guidelines. Statistical interpretation of data revealed good agreement with the comparison method. Method greenness was confirmed by applying three different assessment tools.

X-IRRADIATION OF RIBOSE AND DEOXYRIBOSE DERIVATIVES

1962 ◽  
Vol 40 (1) ◽  
pp. 1553-1565
Author(s):  
D. K. Myers
Keyword(s):  
Aqueous Solution ◽  
Nucleic Acids ◽  
The Other ◽  
Free Sugar ◽  
Blood Samples ◽  
Other Hand ◽  
Dilute Aqueous Solution ◽  
X Irradiation ◽  
In Cells

During X-irradiation of ribosides and deoxyribosides in dilute aqueous solution, purine and sugar moieties were destroyed at approximately the same rate. Pyrimidine moieties, on the other hand, were destroyed more rapidly, resulting in a fairly rapid liberation of free sugar during irradiation of pyrimidine ribosides or deoxyribosides. No marked differences in the rates of destruction of ribose and deoxyribose derivatives were observed in these experiments.Similar reactions were observed during irradiation of blood samples. However, acid-soluble ribonucleotides in the blood proved to be much more sensitive than the nucleic acids or proteins to destruction by X-radiation. The significance of these findings is discussed with relation to the damage produced in cells by X-irradiation.

Apparent molar heat capacities and volumes of unsaturated heterocyclic solutes in aqueous solution at 25 °C

1980 ◽  
Vol 58 (7) ◽  
pp. 704-707 ◽  
Author(s):  
Octavian Enea ◽  
Carmel Jolicoeur ◽  
Loren G. Hepler
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Heterocyclic Compounds ◽  
Infinite Dilution ◽  
Heat Capacities ◽  
Group Additivity ◽  
Standard State ◽  
Apparent Molar Heat Capacities ◽  
Partial Molar Heat Capacities

Measurements at 25 °C with flow calorimeters and densimeters have led to heat capacities and densities of aqueous solutions of 15 unsaturated heterocyclic compounds containing nitrogen. From the results of these measurements we have obtained apparent molar heat capacities and volumes of the solutes. Extrapolations to infinite dilution have led to corresponding standard state apparent and partial molar heat capacities and volumes, which have been analyzed in terms of atomic and group additivity relationships.

Apparent molar heat capacities and volumes of silver nitrate and silver perchlorate in aqueous solution at 298 K

1978 ◽  
Vol 24 (1) ◽  
pp. 111-115 ◽  
Author(s):  
Prem Paul Singh ◽  
Jan Spitzer ◽  
Robert M. McKay ◽  
Keith G. McCurdy ◽  
Loren G. Hepler
Keyword(s):  
Aqueous Solution ◽  
Silver Nitrate ◽  
Heat Capacities ◽  
Apparent Molar Heat Capacities ◽  
Silver Perchlorate

X-IRRADIATION OF RIBOSE AND DEOXYRIBOSE DERIVATIVES

1962 ◽  
Vol 40 (11) ◽  
pp. 1553-1565 ◽  
Author(s):  
D. K. Myers
Keyword(s):  
Aqueous Solution ◽  
Nucleic Acids ◽  
The Other ◽  
Free Sugar ◽  
Blood Samples ◽  
Other Hand ◽  
Dilute Aqueous Solution ◽  
X Irradiation ◽  
In Cells

During X-irradiation of ribosides and deoxyribosides in dilute aqueous solution, purine and sugar moieties were destroyed at approximately the same rate. Pyrimidine moieties, on the other hand, were destroyed more rapidly, resulting in a fairly rapid liberation of free sugar during irradiation of pyrimidine ribosides or deoxyribosides. No marked differences in the rates of destruction of ribose and deoxyribose derivatives were observed in these experiments.Similar reactions were observed during irradiation of blood samples. However, acid-soluble ribonucleotides in the blood proved to be much more sensitive than the nucleic acids or proteins to destruction by X-radiation. The significance of these findings is discussed with relation to the damage produced in cells by X-irradiation.

Apparent molar heat capacities and volumes of aqueous solutions of several 1:1 electrolytes at elevated temperatures

1986 ◽  
Vol 64 (5) ◽  
pp. 926-931 ◽  
Author(s):  
Preet P. S. Saluja ◽  
Jacques C. LeBlanc ◽  
Harold B. Hume
Keyword(s):  
Heat Capacity ◽  
Aqueous Solutions ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Constant Pressure ◽  
Solubility Limit ◽  
Heat Capacities ◽  
Apparent Molar Heat Capacities ◽  
Flow Microcalorimeter ◽  
Good Agreement

The results of heat capacity (Cp) and density (d) measurements at 0.6 MPa and in the temperature range 298.15–373.15 K are presented for several 1:1 electrolytes in water. The flow microcalorimeter and densimeter used for these measurements were modificatons of the room-temperature designs. Data were obtained over concentrations ranging from 0.02 to 1.0 mol kg−1 (or to the solubility limit, whichever was lower). The heat capacity of a solution relative to that of water was measured with a precision of ±0.1 mJ K−1 g−1 at all temperatures. The density of a solution relative to that of water was measured with a precision of ±5 μg cm−3. These Cp and d results were used to calculate the apparent molar heat capacities, [Formula: see text], and volumes, [Formula: see text], at 298.15, 323.15, 348.15, and 373.15 K, at a constant pressure of 0.6 MPa. These results are in good agreement with available literature data.

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