Errors in particle size and concentration analysis of pharmaceuticals

Good particulate products require that particle segregation has been minimized. Moreover representative sampling is essential for adequate quality control of such products. This requires optimum design of procedures and equipment for both sampling and measurement. Representative test samples primarily require that all constituent particles have had equal chance of being taken from a lot of material, given their proportion. Moreover, a sufficient number of particles is necessary for good precision. This article discusses and exemplifies various potential errors during collection of small amounts from powder lots and during in-situ and on-line measurement, so that optimum consideration can be given to the design of adequate analytical procedures. It should be realized that the errors during sampling of particulate materials are very similar to those during collection of small portions for production of pharmaceutical tablets.