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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. Real versus nominal value (philosophy) - Wikipedia

    en.wikipedia.org/wiki/Real_versus_nominal_value...

    Traction power networks routinely operate well above the nominal voltage, but still within the tolerance. For example, a streetcar traction power could be rated 600 ±10% volts nominal, but the actual overhead line voltage would normally be close to 660 volts, only dropping near the nominal value in exceptional conditions.

  4. Mass (mass spectrometry) - Wikipedia

    en.wikipedia.org/wiki/Mass_(mass_spectrometry)

    The nitrogen rule states that organic compounds containing exclusively hydrogen, carbon, nitrogen, oxygen, silicon, phosphorus, sulfur, and the halogens either have an odd nominal mass that indicates an odd number of nitrogen atoms are present or an even nominal mass that indicates an even number of nitrogen atoms are present in the molecular ion.

  5. Concentration - Wikipedia

    en.wikipedia.org/wiki/Concentration

    In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: mass concentration, molar concentration, number concentration, and volume concentration. [1]

  6. Real and nominal value - Wikipedia

    en.wikipedia.org/wiki/Real_and_nominal_value

    If for years 1 and 2 (possibly a span of 20 years apart), the nominal wage and price level P of goods are respectively nominal wage rate: $10 in year 1 and $16 in year 2 price level: 1.00 in year 1 and 1.333 in year 2, then real wages using year 1 as the base year are respectively: $10 (= $10/1.00) in year 1 and $12 (= $16/1.333) in year 2.

  7. Monoisotopic mass - Wikipedia

    en.wikipedia.org/wiki/Monoisotopic_mass

    Nominal mass is a term used in high level mass spectrometric discussions, it can be calculated using the mass number of the most abundant isotope of each atom, without regard for the mass defect. For example, when calculating the nominal mass of a molecule of nitrogen (N 2) and ethylene (C 2 H 4) it comes out as. N 2 (2*14)= 28 Da C 2 H 4

  8. Calibration curve - Wikipedia

    en.wikipedia.org/wiki/Calibration_curve

    A calibration curve plot showing limit of detection (LOD), limit of quantification (LOQ), dynamic range, and limit of linearity (LOL).. In analytical chemistry, a calibration curve, also known as a standard curve, is a general method for determining the concentration of a substance in an unknown sample by comparing the unknown to a set of standard samples of known concentration. [1]

  9. Equivalent concentration - Wikipedia

    en.wikipedia.org/wiki/Equivalent_concentration

    Normality is defined as the number of gram or mole equivalents of solute present in one liter of solution.The SI unit of normality is equivalents per liter (Eq/L). = where N is normality, m sol is the mass of solute in grams, EW sol is the equivalent weight of solute, and V soln is the volume of the entire solution in liters.