# Metrology & measurement

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Background noise exists ubiquitously in analytical instruments, whether or not a sample is applied to the instrument. This document is concerned with mathematical methodologies for estimating the minimum detectable value in case that the most predominant source of measurement uncertainty is background noise. The minimum detectable value can directly and mathematically be derived from the stochastic characteristics of the background noise.

This document specifies basic methods to

— extract the stochastic properties of the background noise,

— use the stochastic properties to estimate the standard deviation (SD) or coefficient of variation (CV) of the response variable, and

— calculate the minimum detectable value based on the SD or CV obtained above.

The methods described in this document are useful for checking the detection of a certain substance by various types of measurement equipment in which the background noise of the instrumental output predominates over the other sources of measurement uncertainty. Feasible choices are visible and ultraviolet absorption spectrometry, atomic absorption spectrometry, atomic fluorescence spectrometry, luminescence spectrometry, liquid chromatography and gas chromatography.

This British Standard specifies requirements for the calibration and classification of torque measuring devices, including those used for the calibration of torque tools.

It describes the method of calibration, calculation of calibration results and the classification of the torque measuring device in a static mode. The information to be given on the certificate of calibration is also listed.

Annex A provides diagrams of the application of torque, and examples for the calibration of torque measuring devices. Annex B gives an example of determining uncertainty of the calibration results of the torque measuring device.