Small But MightySource: MPI Research
By Deni Jo Williams, Melissa Whitsel, and Michael Wallace, MPI Research
As a contract research organization, samples are received for analysis that were taken at a Sponsor or manufacturing location. Production batches of formulated product may fill entire train cars while only one pound of material is submitted for analysis. From that one pound, only one to two grams may be used for analysis. When analyzing samples derived from a much larger batch, the samples must be properly composited to produce meaningful analytical results.
In order to accomplish this, a robust sampling plan should be determined. The sampling plan should ensure that the sample is representative of the whole and that the plan itself can be reliably repeated. The best sampling plan takes into account differences in particle sizes, the degree of heterogeneity of the sample, and intended analysis parameter.
Formulated products which are comprised of components of varying particle sizes are difficult to sample. In some powders, the active ingredient may have a very small particle size while the excipient materials may have a larger particle size. These factors are usually accounted for in the manufacturing process but may be over looked in the sampling process. While the product may be continuously blended during formulation, the sample may be taken without blending. Thus, the concentration of active ingredient in the sample might not be representative of the bulk. Consequently, the assay result will be erroneous although the product may be formulated properly. This could lead to investigations and additional analysis that could have been avoided with a different sampling process. Perhaps a sample could have been taken while blending or a core sample could have been taken throughout the depth of the bulk sample.