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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. Reference materials for stable isotope analysis - Wikipedia

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

    The isotopic reference frame of Standard Mean Ocean Water (SMOW) was established by Harmon Craig in 1961 [17] by measuring δ 2 H and δ 18 O in samples of deep ocean water previously studied by Epstein & Mayeda (1953). [18] Originally SMOW was a purely theoretical isotope ratio intended to represent the mean state of the deep ocean.

  4. Standard Reference Method - Wikipedia

    en.wikipedia.org/wiki/Standard_Reference_Method

    The Standard Reference Method or SRM [1] is one of several systems modern brewers use to specify beer color. Determination of the SRM value involves measuring the attenuation of light of a particular wavelength (430 nm) in passing through 1 cm of the beer, expressing the attenuation as an absorption and scaling the absorption by a constant (12.7 for SRM; 25 for EBC).

  5. Internal standard - Wikipedia

    en.wikipedia.org/wiki/Internal_standard

    Selecting an internal standard in inductively coupled plasma spectroscopy can be difficult, because signals from the sample matrix can overlap with those belonging to the analyte. Yttrium is a common internal standard that is naturally absent in most samples. It has both a mid-range mass and emission lines that don't interfere with many analytes.

  6. 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]

  7. Calibration gas - Wikipedia

    en.wikipedia.org/wiki/Calibration_gas

    A calibration gas is a reference gas or gas mixture used as comparative standard in the calibration of analytical instruments, like gas analysers or gas detectors.Therefore, a calibration gas has to be of a precisely defined nature or composition, like zero gas or span gas, for example 500 ppm carbon monoxide in nitrogen.

  8. Standard solution - Wikipedia

    en.wikipedia.org/wiki/Standard_solution

    A standard solution created from a secondary standard cannot have its concentration accurately known without stoichiometric analysis against a primary standard. An example of a secondary standard is sodium hydroxide, a hydroscopic compound that is highly reactive with its surroundings. The concentration of a standard solution made with sodium ...

  9. Reference range - Wikipedia

    en.wikipedia.org/wiki/Reference_range

    The standard definition of a reference range for a particular measurement is defined as the interval between which 95% of values of a reference population fall into, in such a way that 2.5% of the time a value will be less than the lower limit of this interval, and 2.5% of the time it will be larger than the upper limit of this interval, whatever the distribution of these values.

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