Aims: Lenticulesconsit of control-dried plano convex discs in which biologically-active materials are contained within a water-soluble matrix. They can be produced to contain stable numbers of bacteria from 10 cfu lenticule–1 to 108 cfu lenticule–1 with a wide variety of organisms. These experiments were carried out to validate their use as a tool for internal quality control in quantitative microbiology.

Methods and Results: The Lenticules were used routinely in standard quantitative microbiological procedures across five laboratories. Results showed the materials to be stable, homogenous and capable of identifying systematic errors.

Conclusions: The Lenticules provide suitable, stable control materials.

Significance and Impact of the Study: Routine internal quality control of quantitative measurements is greatly improved; the materials are easy to use and enable comparisons between laboratories to be made.