# The Natural Mineral Water, Spring Water and Bottled Drinking Water (England) Regulations 2007, Schedule 7: Performance characteristics for analysing the constituents in Schedule 6

Extent: E+W

Notes:
1.The method of analysis used to measure the concentration of the constituents in Schedule 6 shall be capable of measuring concentrations equal to the parametric value with the specified accuracy, precision and detection limits.
2.Regardless of the sensitivity of the method of analysis, the result must be expressed to at least the same number of decimal places as the maximum limit set out in Schedule 6 for the particular constituent being analysed.
3.Accuracy is the systematic error and represents the difference between the average value of a large number of repeated measurements and the exact value.
4.Precision represents the random error and is expressed in general as the standard deviation (within a batch and between batches) of a sample of results from the average.
5.Acceptable precision is equal to twice the relative standard deviation.
6.The detection limit is—
(a)three times the relative standard deviation within a batch of a natural sample containing a low concentration of the constituent; or
(b)five times the relative standard deviation within a batch of a virgin sample.
7.The method should make it possible to determine cyanide in all its forms.
Constituent
Accuracy of parametric value in %
Precision of parametric value
Detection limit of parametric value in %
Antimony
25
25
25
Arsenic
10
10
10
Barium
25
25
25
Cadmium
10
10
10
Chromium
10
10
10
Copper
10
10
10
Cyanides
10
10
10
Fluoride
10
10
10
Lead
10
10
10
Manganese
10
10
10
Mercury
20
10
20
Nickel
10
10
10
Nitrate
10
10
10
Nitrite
10
10
10
Selenium
10
10
10

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Source: https://www.legislation.gov.uk/uksi/2007/2785/schedule/7 (the official version)
Page: https://openlegislation.uk/natural-mineral-water-spring-water-and-bottled-drinking-water-england-regulations-2007/schedule-7
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.