ISO TR 7821:1982 pdf free
ISO TR 7821:1982 pdf free.Tobacco – Preparation and constitution of identical samples from the same lot
Moreover, it is again recalled that the aim in view is not to make up samples representing the original lot but samples which are as similar as possible to each other.
Starting from these principles, and with a total number of cigarettes in all samples of 500, or 25 packets, the method to be used is as follows :
a) Select 3 units from one box. Keep two whole units, but remove half of the third unit to give a total of 25 packets.
b) Open each packet and distribute the cigarettes into 10 samples (2 cigarettes per sample).
c) In this manner, 10 samples each of 50 cigarettes are constituted and these will be as similar to each other as possible.
This case is called upon only as a last resort, because it poses difficult specific problems and because it is rare that leaves or strips themselves will constitute the material on which the collaborative, physical or chemical studies will be carried out.
Similar samples of leaves or strips are usualy used only for tests concerning changes of industrial processes. These tests require the use of industrial production machinery (for example mixing boxes) and the sampling procedure is outside the scope of this Technical Report.
However, if the lot consists of leaves or strips, analysis of the actual requirements shows that it is possible, without disadvantage to the method of test, to modify the physical aspect of the material and to use one of the methods described in the above examples.
An example will ilustrate this point, as it was an actual case which occurred some years ago.
There were various procedures to be tested for the determination of the moisture content of tobacco for different varieties of leaves1) and each initial lot to be sampled was made up of leaves. Detailed analysis of the problem showed that sampling should not be carried out on the leaves, but after treating them and reducing them to cut tobacco.
Collaborative tests were carried out in good conditions with correctly sampled lots of cut tobacco.ISO TR 7821 pdf download.
