Good Manufacturing Practice (GMP) is the part of quality assurance that ensures that products are produced and controlled consistently and reliably. This consistency of production and control is essential. It can only come about by having clear descriptions of the way in which the work will be done.

GMP specifically addresses risks that cannot be fully controlled by testing of the final product:

• Cross-contamination

• Mix-ups

These risks can best be controlled by having a properly managed system of working that takes them into account. This means that there must be good design, sound operation, and planned maintenance of facilities. It also means that the quality checking system must be designed with these risks in mind and set out to find whether any errors have occurred. Let us look at this problem in another way. If we do not know what sort of cross contamination we have, then the work of the analyst is very difficult. The analyst should ideally know what to test for before commencing testing. In other words, if we do not know what the likely cross-contaminant is then we cannot analyse for it.

There are a number of basic requirements for GMP, which we shall look at next.