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In United States Pharmacopeia (USP) General Chapter <711> Dissolution, there are four dissolution apparatuses standardized and specified. [6] They are: USP Dissolution Apparatus 1 – Basket (37 °C ± 0.5 °C ) USP Dissolution Apparatus 2 – Paddle (37 °C ± 0.5 °C) USP Dissolution Apparatus 3 – Reciprocating Cylinder (37 °C ± 0.5 °C)
USP establishes documentary (written) and reference (physical) standards for medicines, food ingredients, dietary supplement products, and ingredients. These standards are used by regulatory agencies and manufacturers to help to ensure that these products are of the appropriate identity, as well as strength, quality, purity, and consistency.
13 C NMR Spectrum of DMSO-d 6. Pure deuterated DMSO shows no peaks in 1 H NMR spectroscopy and as a result is commonly used as an NMR solvent. [2] However commercially available samples are not 100% pure and a residual DMSO-d 5 1 H NMR signal is observed at 2.50ppm (quintet, J HD =1.9Hz).
Proteins that have high hydrophobic amino acid content on the surface have low solubility in an aqueous solvent. Charged and polar surface residues interact with ionic groups in the solvent and increase the solubility of a protein. Knowledge of a protein's amino acid composition will aid in determining an ideal precipitation solvent and methods.
Deuterated chloroform is a general purpose NMR solvent, as it is not very chemically reactive and unlikely to exchange its deuterium with its solute, [9] and its low boiling point allows for easy sample recovery. It, however, it is incompatible with strongly basic, nucleophilic, or reducing analytes, including many organometallic compounds.
As hydrazoic acid, the protonated form of the azide anion, has a very low reduction potential E° red = -3,09 volt, and is even a stronger reductant than lithium (E° red = -3.04 volt), dry solid sodium azide can be added to molten metallic sodium (E° red = -2,71 volt) under strict anoxic conditions (e.g., in a special anaerobic glovebox with ...
The perchlorate ion forms when they dissolve in water, dissociating into ions. Many perchlorate salts also exhibit good solubility in non-aqueous solvents . [ 4 ] Four perchlorates are of primary commercial interest: ammonium perchlorate (NH 4 )ClO 4 , perchloric acid HClO 4 , potassium perchlorate KClO 4 and sodium perchlorate NaClO 4 .
[11] [12] SAG allows the unrestricted scaling of alignment over a wide range and can be used for aqueous as well as organic solvents, depending on the polymer used. As a first example in organic solvents, RDC measurements in stretched polystyrene (PS) gels swollen in CDCl 3 were reported as a promising alignment method.