6.—(1) Subject to sub paragraph (2), any method of analytical determination may be used to prove excess of an overall migration limit in relation to a plastic material or article.
(2) In any proceedings for an offence under these Regulations where it is alleged that a plastic material or article does not comply with regulation 9 it shall be a defence for the accused to prove that–
(a)if an aqueous simulant specified in Schedule 3 had been used, and the analytical determination of the total quantity of substances released by a sample of the plastic material or article tested had been carried out by evaporation of the simulant and weighing of the residue; or
(b)if rectified olive oil or any of its substitutes had been used as a simulant and–
(i)a sample of the plastic material or article had been weighed before and after contact with the simulant;
(ii)the simulant absorbed by the sample had been extracted and determined quantitatively;
(iii)the quantity of simulant so found had been subtracted from the weight of the sample measured after contact with the simulant; and
(iv)the difference between the initial and corrected final weights had been determined to represent the overall migration of the sample examined,
there would have been no such excess so determined.