pH, density, specific gravity, melting range, optical rotation, osmolality, viscosity and related tests.
| Tests |
|
|---|---|
| Method | Tested to the USP chapter, monograph or customer specification you choose. |
| Results | Reported against your monograph or specification, with pass/fail where limits apply. |
| Price | Quoted per project |
Each test measures one physical property under stated conditions. Where a USP general chapter is listed, the test follows it as the monograph directs; otherwise it follows your monograph or specification.
Measures the pH of a solution or liquid product with a calibrated pH meter, at the concentration and temperature the monograph or specification states.
Density is mass per unit volume. We measure it with a pycnometer, a vessel of calibrated volume that is weighed empty and then filled with the sample, or with a digital density meter, which measures the density of a liquid sample electronically. Density changes with temperature, so the result is reported with the temperature of measurement, and the temperature and technique follow your monograph or specification.
Specific gravity compares the density of a liquid with the density of water, so it is a ratio with no units. We determine it with the same pycnometer or digital density meter, and report it with the sample and water temperatures your monograph or specification states.
Determines the temperature range over which a substance changes from solid to liquid. USP <741> notes that a highly pure material may appear to melt almost at once while most show a range, and that sample size, particle size, heat diffusion and heating rate affect the result, so the conditions follow the monograph.
Measures the angle through which a substance or its solution rotates plane-polarized light. USP <781> describes this as a property of optically active substances, generally those with one or more asymmetric centers. Results are reported as the observed angle of rotation, or as the specific rotation calculated from it, with the measurement conditions the monograph states.
Measures the osmotic concentration of a solution, reported as osmolality or osmolarity as the monograph or specification requires. Osmolality is expressed per kilogram of solvent and osmolarity per liter of solution; USP <785> covers both.
Determines the viscosity of a Newtonian fluid, one whose viscosity does not depend on the rate of shear, which is the scope USP <911> describes for capillary methods.
Measures the torque on a rotor turning at constant speed in the liquid, the principle USP <912> describes. It gives the viscosity of Newtonian fluids and the apparent viscosity of non-Newtonian fluids; because viscosity depends on temperature, the temperature is controlled and reported.
Checks that a stated amount of a solid dissolves completely in the stated solvent and that the solution is clear, as the monograph or specification describes. It shows whether the material dissolves as expected at that concentration and is free of insoluble matter. The result is reported as conforming or not conforming.
For a suspension or similar product, the test looks at how the solid settles under the conditions your monograph or specification sets, and where the document asks, whether it disperses again on shaking. The observation or measured value is reported against the acceptance criteria in your document; tell us the procedure and criteria.
The sample is weighed before and after the conditions your monograph or specification defines, and the loss of weight is reported against the acceptance criteria in that document. The procedure, conditions and criteria come from your document; tell us which applies.
Send the material or product sealed and labeled, with its storage conditions.
Tell us the monograph or specification, the tests you need and the number of samples. We work to the current official USP-NF unless you name another applicable edition, and confirm the sample amount at quote.
Questions about a sample or a method, call 360-967-7010 or email [email protected].
