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Regulation 7(1) and (2) and paragraph 2(c)of Part 1 of Schedule 3, paragraph 2(c) of Part 2 of Schedule 3 and Notes 1 and 2 of Schedule 7

SCHEDULE 6 Maximum limits for constituents of natural mineral waters

  

Note:

The constituents described above refer to constituents naturally present in the water at source and not to substances present as the result of contamination.

Regulation 7(2)

SCHEDULE 7 Performance characteristics for analysing the constituents in Schedule 6

  

Notes:

1.  The method of analysis used to measure the concentration of the constituents in Schedule 6 must 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.