Confirmation of performance is desirable from time to time for every analytical instrument.
The need for validation can arise from a change of operators, a peculiar result, an unfamiliar material, or simply from equipment wear and tear. Micromeritics products, with a few exceptions, do not require calibration per se; they derive results from well-established laws utilizing detection of basic parameters such as time, temperature, pressure, mass, and the like. Micromeritics instruments, nevertheless, are no exception to the desirability for periodic performance evaluation, because detectors, like everything else, age, drift, and occasionally fail.
An effective means for detecting operational mistakes or erroneous applications and for assuring consistent, reproducible results is to retain a quantity of one or more appropriate materials with known, well-characterized properties which can be used to test instrument performance. The reference materials subsequently listed by primary property are offered by Micromeritics for this corroborative purpose. Each has been carefully selected to be representative of the parameter, or parameters, for which it is recommended, to be non-hazardous, and to have an extended shelf life.
The lot of material from which each reference portion was extracted has been repeatedly analyzed. This has been done on a number of instruments, by different operators, and, in some cases, even using different techniques. We do not claim our reference materials to be standards. The extensive, blind testing utilizing independent laboratories which would enable us to make such a statement has not been undertaken. We are confident, nevertheless, and so assert, that an instrument giving the result, or results, within the limits specified with each reference material is operating satisfactorily.
When you order a reference material, you will receive with it information on how best to prepare it for analysis (for example, how to disperse it in a liquid, degas time and temperature, and the like), recommended quantity for a test as appropriate for the instrument in question, and other essential data (for example, density, starting diameter, flow path, etc.). Material properties are tabulated along with their limits of accuracy. As appropriate, a typical property trace such as a size distribution, an adsorption and desorption isotherm, or an intrusion and extrusion curve is included.
|Alumina Chips, s.s.a.:
2360/2370/2375 = 0.50 m2/g (N2), (15-g pk)
all others = 0.46 m2/g (Kr), (15-g pk)
|Glass Powder, s.s.a. = 5.3 m2/g, (10-g pk)
|Carbon Black, 24.1 m2/g
s.s.a. = 215 m2/g, (10-g pk) a.p.d. = 115 Å
|Note s.s.a. = specific surface area, p.v. = pore volume, a.p.d. = average pore diameter
TriStar II Reference Materials
The silica-alumina is a typical porous high surface area reference material. The surface area of silica-alumina typically exceeds 200 m2/g and the pore size is a nominal 100 Å. This material is recommended for users that analyze amorphous materials with surface area ranging from 10 to greater than 300 m2/g and for both non-porous and porous materials in the 40-3000 Å range. Silica-alumina is suitable for use with BET, t-plot, and BJH pore size reports.
Standard Reference Blacks are available from 20 to greater than 100 m2/g. These are stable and very well characterized materials. They are recommended for all users but may be especially suited for researchers in the carbon, tire, and filler industries. The carbon black reference materials are suitable for use with the BET and STSA reports.
A 5 m2/g glass reference material is recommended for industries and users that characterize materials in the 1 through 50 m2/g range. Glass reference material is suitable for use with the BET surface area report.
Low surface area alpha alumina (less than 1 m2/g) is available for use with krypton. Alpha alumina is recommended for researchers in the pharmaceutical, abrasives, soil, and other areas that require the characterization of materials with surface areas less than 1 m2/g. Alpha alumina reference material is recommended for use with krypton and the BET surface area report.