—(1) An inspector may purchase any article advertised for sale or offered or exposed for sale, which he knows or has reason to believe to consist of or contain any controlled drug.
(2) The person in possession or charge of the article mentioned in paragraph (1) shall supply that article to the inspector and shall not charge more than the advertised or a reasonable price therefor.
(3) An inspector making any such purchase may —
select the actual case, bottle or package which he requires; or
demand to be served from any receptacle pointed out by him,
and the person in possession or charge shall comply with such requirement or demand.
(4) An inspector purchasing any article with the intention of submitting that article to analysis shall immediately on completion of the purchase —
notify the seller or his agent selling the article his intention to have the article analysed;
divide the article into 3 parts;
mark and seal or fasten up each one of the parts in such manner as its nature will permit;
deliver one of the parts to the seller or his agent and another to the Director of Scientific Servicesfor analysis; and
retain the third part for comparison.