Performance criteria of the instrumental method of analysis
4.—(1) The detection limit for lead and cadmium must be equal to or lower than—
(a)0.1 mg/litre for lead; and
(b)0.01 mg/litre for cadmium,
where the detection limit is defined as the concentration of the element in the 4% acetic acid solution, as referred to in paragraph 3(3), which gives a signal equal to twice the background noise of the instrument.
(2) The limit of quantification for lead and cadmium must be equal to or lower than:
(a)0.2 mg/litre for lead; and
(b)0.02 mg/litre for cadmium.
(3) Recovery: the recovery of lead and cadmium added to the 4% acetic acid solution, as referred to in paragraph 3(3), must lie within 80-120% of the added amount.
(4) Specificity: the instrumental method of analysis used must be free from matrix and spectral interferences.