Analysis of samplesN.I.
1.—(1) The district council must ensure that each sample is analysed in accordance with Annex III to Directive 98/83 and this Schedule.
(2) For each parameter specified in the first column of Table 1 in Part 2 the method of analysis is specified in the second column of that table.
(3) For each parameter specified in the first column of Table 2 in Part 2 the method of analysis is one that is capable of—
(a)measuring concentrations and values with the trueness and precision specified in the second and third columns of that table; and
(b)detecting the parameter at the limit of detection specified in the fourth column of that table.
(4) For hydrogen ion, the method of analysis must be capable of measuring a value with a trueness of 0.2pH unit and a precision of 0.2 pH unit.
(5) The method of analysis used for odour and taste parameters must be capable of measuring values equal to the parametric value with a precision of 1 dilution number at 25 ºC.
(6) For the purpose of this paragraph—
“limit of detection” is—
(a)three times the relative within-batch standard deviation of a natural sample containing a low concentration of the parameter; or
(b)five times the relative within-batch standard deviation of a blank sample;
“precision” (the random error) is twice the standard deviation (within a batch and between batches) of the spread of results about the mean;
“trueness” (the systematic error) is the difference between the mean value of the large number of repeated measurements and the true value.