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In analytical chemistry, the detection limit, lower limit of detection, also termed LOD for limit of detection or analytical sensitivity (not to be confused with statistical sensitivity), is the lowest quantity of a substance that can be distinguished from the absence of that substance (a blank value) with a stated confidence level (generally 99%).
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]
NAA can detect up to 74 elements depending upon the experimental procedure, with minimum detection limits ranging from 0.1 to 1x10 6 ng g −1 depending on element under investigation. Heavier elements have larger nuclei, therefore they have a larger neutron capture cross-section and are more likely to be activated.
There are different definitions within laboratory quality control, wherein "analytical sensitivity" is defined as the smallest amount of substance in a sample that can accurately be measured by an assay (synonymously to detection limit), and "analytical specificity" is defined as the ability of an assay to measure one particular organism or ...
Memorial in Jena, Germany to Ernst Karl Abbe, who approximated the diffraction limit of a microscope as = , where d is the resolvable feature size, λ is the wavelength of light, n is the index of refraction of the medium being imaged in, and θ (depicted as α in the inscription) is the half-angle subtended by the optical objective lens (representing the numerical aperture).
The control limits are set at three standard deviations on either side of the process mean, and are known as the upper control limit (UCL) and lower control limit (LCL) respectively. [2] If the process data plotted on the control chart remains within the control limits over an extended period, then the process is said to be stable. [2] [3]
It is typically used for monitoring change detection. [1] CUSUM was announced in Biometrika, in 1954, a few years after the publication of Wald's sequential probability ratio test (SPRT). [2] E. S. Page referred to a "quality number" , by which he meant a parameter of the probability distribution; for example, the mean. He devised CUSUM as a ...
Considering detection limit, both TCD and FID reach low concentration levels (inferior to ppm or ppb). [2] Both of them require pressurized carrier gas (Typically: H 2 for FID, He for TCD) but due to the risk associated with storing H 2 (high flammability, see Hydrogen safety), TCD with He should be considered in locations where safety is crucial.