SAMPLING PROCEDURES

SAMPLING PROCEDURES Assessment of the quality of herbal drugs is directly dependent on the selection of sample for examination. These samples must be truly representative of the material undergoing analysis. The reliability of any analysis will depend upon how truly that sample represents the whole batch. In case of a small consignment, all parts should be examined and where this is impractical, portions for analysis should be taken from several different parts of the consignment to ensure that the material that has been supplied is homogeneous. The United States Pharmacopoeia (USP 1994) has prescribed very definite sampling procedures.

If the material is in powdered form or the pieces are less then 1 cm in any direction samples are taken by extracting cores from top to bottom of the container in each direction. If the sample size is less than 100 Kg, at least 250 g of material is taken. If the sample size is greater than 100 Kg repeated samples are taken, according to the schedule below, mixed and quartered.

Number of packages in shipment Number of packages to be sampled 1-10 1-3 10-25 2-4 25-50 3-6 50-75 6-8 75-100 8-10

Two of the diagonal quarters are rejected and the remaining two quarters carefully mixed and re-quartered until two of the quarters weigh as near as possible to, but not less than, 250 g. Samples of vegetable drugs consisting of pieces greater in size than 1 cm are taken by hand from different parts of the container or containers. If the consignment size is less then 100 Kg the minimum sample size is 500 g.

If the consignment size is greater then 100 Kg repeated sample are taken and mixed and quartered as in the first procedure until two of the quarters weigh as near as possible to, but less than, 500 g.

Sampling of Material in Bulk Inspect each container/packing unit (pack etc.) for conformity with pharmacopoeial monographs or other requirements regarding packaging and labelling. Check the integrity of the outer package and note any defects which may influence the quality or stability of the contents (physical damage, moisture etc.). Damaged containers are sampled individually. If initial inspection indicates that the batch is uniform, then the samples are to be taken in the following manners:

When a batch consists of 5 containers/units, sample is taken from all of them; and from a batch of 6-50 units, a sample from 5 packages is taken. In the case of batch of over 50 containers-sample 10% of the units, rounding up the number of units to the next highest figure of ten, are taken. For example, 51 units would be sampled as for 60.

After opening, containers are inspected for the following parameters and selected for sampling: Organoleptic characteristics (colour, texture and odour) Presentation of the material (raw, cut, crushed, compressed) The presence of admixtures, foreign matter (sand, glass particles, dirt), mould, or signs of decay The presence of insects The presence of packaging material originating from poor or degraded containers

From each container/package selected, 3 original samples are taken, taking care to avoid fragmentation. Samples should be taken from the upper, middle and lower parts. In the case of sacks and packages, 3 individual samples are taken by hand from a depth of not less than 10 cm from the top, and after cutting into the side of the package from the middle and lower parts. Samples of seeds are withdrawn with a grain probe. Material in boxes is first sampled from the upper layer, then approximately half the content is removed and samples are taken again. Finally, after further removal of material, another sample is taken from the bottom. Samples should be as uniform as possible in mass. Individual samples are combined into a pooled sample which should be mixed carefully.

The average sample is obtained by quartering The average sample is obtained by quartering. The processes of quartering consists of placing the sample, adequately mixed, formed as an even and square-shaped heap and dividing it diagonally into four equal parts. The two opposite parts are then taken diagonally, and carefully mixed. The process is repeated as necessary until the required quantity is obtained.

Any remaining material should be returned to the batch Any remaining material should be returned to the batch. The final samples are assembled and tested for the following characteristics: Degree of fragmentation (sieve test) Identity and level of impurities Determination of moisture and ash content Assay of active ingredients, where possible A portion of the final sample should be retained to serve as reference material, which may also be used for the purpose of checking quality control tests, if necessary.

Sampling of Material in Retail Packages From each wholesale container (boxes, cartons etc.) selected for sampling, two consumer packages are usually taken at random. From small batches (1 - 5 boxes), 10 consumer packages are taken. The pooled samples are prepared by mixing the contents of selected consumer packages and procedure followed as described above for the final sample.