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  2. Certified reference materials - Wikipedia

    en.wikipedia.org/wiki/Certified_reference_materials

    A certified reference material is a particular form of measurement standard. Reference materials are particularly important for analytical chemistry and clinical analysis. [2] Since most analytical instrumentation is comparative, it requires a sample of known composition (reference material) for accurate calibration.

  3. Reagent Chemicals - Wikipedia

    en.wikipedia.org/wiki/Reagent_Chemicals

    Chemicals that meet this standard may be sold as "ACS Reagent Grade" materials. Reagent standards relieve chemists of concern over chemical purity. "ACS Reagent Grade", is regarded as a gold standard measure and is in some cases required for use in chemical manufacturing, usually where stringent quality specifications and a purity of equal to ...

  4. Reference materials for stable isotope analysis - Wikipedia

    en.wikipedia.org/wiki/Reference_materials_for...

    The δ values and absolute isotope ratios of common reference materials are summarized in Table 1 and described in more detail below. Alternative values for the absolute isotopic ratios of reference materials, differing only modestly from those in Table 1, are presented in Table 2.5 of Sharp (2007) [1] (a text freely available online), as well as Table 1 of the 1993 IAEA report on isotopic ...

  5. Primary standard - Wikipedia

    en.wikipedia.org/wiki/Primary_standard

    A primary standard in metrology is a standard that is sufficiently accurate such that it is not calibrated by or subordinate to other standards. Primary standards are defined via other quantities like length, mass and time. Primary standards are used to calibrate other standards referred to as working standards. [1] [2] See Hierarchy of Standards.

  6. Globally Harmonized System of Classification and Labelling of ...

    en.wikipedia.org/wiki/Globally_Harmonized_System...

    The pictogram for harmful substances of the Globally Harmonized System of Classification and Labelling of Chemicals.. The Globally Harmonized System of Classification and Labelling of Chemicals (GHS) is an internationally agreed-upon standard managed by the United Nations that was set up to replace the assortment of hazardous material classification and labelling schemes previously used around ...

  7. Drug reference standard - Wikipedia

    en.wikipedia.org/wiki/Drug_reference_standard

    A drug reference standard or pharmaceutical reference standard is a highly characterized material suitable to test the identity, strength, quality and purity of substances for pharmaceutical use and medicinal products.

  8. Trump says US should 'NOT GET INVOLVED' in conflict in Syria

    www.aol.com/news/trump-says-us-not-involved...

    WASHINGTON (Reuters) -President-elect Donald Trump said on Saturday the U.S. should not be involved in the conflict in Syria, where rebel forces are threatening the government of President Bashar ...

  9. Glossary of chemistry terms - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_chemistry_terms

    This glossary of chemistry terms is a list of terms and definitions relevant to chemistry, including chemical laws, diagrams and formulae, laboratory tools, glassware, and equipment. Chemistry is a physical science concerned with the composition, structure, and properties of matter , as well as the changes it undergoes during chemical reactions ...

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