THE COMPOSITION OF THE STRONG PHOSPHORIC ACIDS

1956 ◽  
Vol 34 (6) ◽  
pp. 785-797 ◽  
Author(s):  
Anna-Liisa Huhti ◽  
Phoebus A. Gartaganis
Keyword(s):  
Room Temperature ◽  
Orthophosphoric Acid ◽  
Dynamic Equilibrium ◽  
Free Water ◽  
Phosphorus Pentoxide ◽  
Mole Percent ◽  
Pyrophosphoric Acid ◽  
Set Up ◽  
Phosphoric Acids

The composition of the strong phosphoric acids was studied in the range 68.8 to 86.3% phosphorus pentoxide by weight. Improved filter-paper chromatography made possible the quantitative determination of the nine lower members of the series, and occasionally up to the twelfth member. It was found that when the strong phosphoric acids are prepared by heating at 350 °C, a dynamic equilibrium between the component acids is set up which persists when the mixtures are cooled to room temperature. Only linear condensed polyphosphoric acids were present in the range studied. The composition corresponding to 100% orthophosphoric acid contains about 6 mole percent each of pyrophosphoric acid and “free water”. As the mole ratio of water to phosphorus pentoxide decreases, the number of component acids increases. Orthophosphoric acid is present to an appreciable extent in the stronger phosphoric acids. “Hexametaphosphoric acid” is not a separate chemical entity, but a mixture of higher linear polyphosphoric acids.

scholarly journals Stability Indicating Validated HPLC Method for the Determination of Aceclofenac and Misoprostol in Bulk and Pharmaceutical Formulation

2020 ◽  
Vol 11 (4) ◽  
pp. 7848-7853
Author(s):  
Syed Rafi ◽  
Kantipudi Rambabu
Keyword(s):  
Room Temperature ◽  
Orthophosphoric Acid ◽  
Pharmaceutical Preparation ◽  
Hplc Method ◽  
Alkaline Peroxide ◽  
Rp Hplc ◽  
Ich Guidelines ◽  
Simultaneous Evaluation ◽  
Formulation Analysis

For the simultaneous evaluation of Aceclofenac and Misoprostol using RP-HPLC, an accurate, rapid, economical, and straightforward, reliable assay technique was developed and demonstrated. The proposed method achieved effective chromatographic separation by using an inertsil ODS column (150mmx4.6mm, 3.5), acetonitrile, and 0.1 percent orthophosphoric acid (OPA) (50:50 v/v) as a mobile phase with a flow rate of 1 ml/min and a wavelength of 227 nm. The retention time (Rt) of Aceclofenac was 3.189 minutes and Misoprostol was 6.966 minutes. Chromatography was performed isocratically at room temperature with a run time of around 10 minutes. The suitability parameters of the system were investigated by multiplying the quality six times, and the results were well within acceptable limits. The linearity analysis was conducted at 10 percent to 150 percent stages, with a regression coefficient of 0.999. Aceclofenac and Misoprostol had LOD and LOQ values of 0.063 ug/ml, 0.063 g/ml, and 0.208 ug/ml and 0.208 g/ml, respectively. The drug was recovered at a rate of 98-102 percent, which means that the recovery is within reasonable limits. The validation results were satisfactory, and the approach was found to be suitable for bulk and formulation analysis. As a result, it was obvious that the proposed approach was ideal for routine pharmaceutical preparation review and quality control. Validation results were very close to the appropriate maximum. RSD values of less than 2.0 percent indicate that this approach is accurate and precise. The above method was used to perform a retail formulation assay, which showed that 100.24 percent of the formulation was present. Degradation stress conditions in acidic, alkaline, peroxide, and thermal media were investigated. Under ideal conditions, the established method provided efficient, precise, and accurate results. According to ICH guidelines, the approach was justified.

Interactions Between Al and Cr Thin Films

1976 ◽  
Vol 34 ◽  
pp. 638-639
Author(s):  
R. M. Anderson ◽  
T. M. Reith ◽  
M. J. Sullivan ◽  
E. K. Brandis
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Vacuum System ◽  
Processing Temperature ◽  
Diffusion Couples ◽  
Electronic Circuits ◽  
Intermetallic Formation ◽  
Si Substrates ◽  
Aluminum Silicon

Thin films of aluminum or aluminum-silicon can be used in conjunction with thin films of chromium in integrated electronic circuits. For some applications, these films exhibit undesirable reactions; in particular, intermetallic formation below 500 C must be inhibited or prevented. The Al films, being the principal current carriers in interconnective metal applications, are usually much thicker than the Cr; so one might expect Al-rich intermetallics to form when the processing temperature goes out of control. Unfortunately, the JCPDS and the literature do not contain enough data on the Al-rich phases CrAl7 and Cr2Al11, and the determination of these data was a secondary aim of this work.To define a matrix of Cr-Al diffusion couples, Cr-Al films were deposited with two sets of variables: Al or Al-Si, and broken vacuum or single pumpdown. All films were deposited on 2-1/4-inch thermally oxidized Si substrates. A 500-Å layer of Cr was deposited at 120 Å/min on substrates at room temperature, in a vacuum system that had been pumped to 2 x 10-6 Torr. Then, with or without vacuum break, a 1000-Å layer of Al or Al-Si was deposited at 35 Å/s, with the substrates still at room temperature.

STEM and ELS Observation of Early Oxide Formation on the Surface of Cr Thin Films

1980 ◽  
Vol 38 ◽  
pp. 412-413
Author(s):  
Fumio Watari ◽  
J. M. Cowley
Keyword(s):  
Thin Films ◽  
Optical System ◽  
Room Temperature ◽  
Oxide Formation ◽  
Initial Nucleation ◽  
Diffraction Patterns ◽  
Relationship Of ◽  
Multiple Twinning ◽  
Moderately High Temperature

STEM coupled with the optical system was used for the investigation of the early oxidation on the surface of Cr. Cr thin films (30 – 1000Å) were prepared by evaporation onto the polished or air-cleaved NaCl substrates at room temperature and 45°C in a vacuum of 10−6 Torr with an evaporation speed 0.3Å/sec. Rather thick specimens (200 – 1000Å) with various preferred orientations were used for the investigation of the oxidation at moderately high temperature (600 − 1100°C). Selected area diffraction patterns in these specimens are usually very much complicated by the existence of the different kinds of oxides and their multiple twinning. The determination of the epitaxial orientation relationship of the oxides formed on the Cr surface was made possible by intensive use of the optical system and microdiffraction techniques. Prior to the formation of the known rhombohedral Cr2O3, a thin spinel oxide, probably analogous to γ -Al203 or γ -Fe203, was formed. Fig. 1a shows the distinct epitaxial growth of the spinel (001) as well as the rhombohedral (125) on the well-oriented Cr(001) surface. In the case of the Cr specimen with the (001) preferred orientation (Fig. 1b), the rings explainable by spinel structure appeared as well as the well defined epitaxial spots of the spinel (001). The microdif fraction from 20A areas (Fig. 2a) clearly shows the same pattern as Fig. Ia with the weaker oxide spots among the more intense Cr spots, indicating that the thickness of the oxide is much less than that of Cr. The rhombohedral Cr2O3 was nucleated preferably at the Cr(011) sites provided by the polycrystalline nature of the present specimens with the relation Cr2O3 (001)//Cr(011), and by further oxidation it grew into full coverage of the rest of the Cr surface with the orientation determined by the initial nucleation.

A New Method for Direct Determination of the Recoilless Fraction with Application to Magnetic Nanoparticles

2002 ◽  
Vol 721 ◽  
Author(s):  
Monica Sorescu
Keyword(s):  
Room Temperature ◽  
Average Particle Size ◽  
Direct Determination ◽  
Average Particle ◽  
Lattice Method ◽  
Recoilless Fraction ◽  
Single Room ◽  
Magnetite Particles ◽  
Physical Mixtures

AbstractWe propose a two-lattice method for direct determination of the recoilless fraction using a single room-temperature transmission Mössbauer measurement. The method is first demonstrated for the case of iron and metallic glass two-foil system and is next generalized for the case of physical mixtures of two powders. We further apply this method to determine the recoilless fraction of hematite and magnetite particles. Finally, we provide direct measurement of the recoilless fraction in nanohematite and nanomagnetite with an average particle size of 19 nm.

Single Crystal Growth of High-Pressure Phases of Ice and Salt Hydrate Far Below the Original Melting Point by Mixing Alcohol: Crystal Structure Determination of Magnesium Chloride Heptahydrate

2020 ◽  
Author(s):  
Keishiro Yamashita ◽  
Kazuki Komatsu ◽  
Hiroyuki Kagi
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Crystal Growth ◽  
Single Crystal ◽  
Room Temperature ◽  
Growth Technique ◽  
Salt Hydrate ◽  
X Ray

An crystal-growth technique for single crystal x-ray structure analysis of high-pressure forms of hydrogen-bonded crystals is proposed. We used alcohol mixture (methanol: ethanol = 4:1 in volumetric ratio), which is a widely used pressure transmitting medium, inhibiting the nucleation and growth of unwanted crystals. In this paper, two kinds of single crystals which have not been obtained using a conventional experimental technique were obtained using this technique: ice VI at 1.99 GPa and MgCl<sub>2</sub>·7H<sub>2</sub>O at 2.50 GPa at room temperature. Here we first report the crystal structure of MgCl2·7H2O. This technique simultaneously meets the requirement of hydrostaticity for high-pressure experiments and has feasibility for further in-situ measurements.

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