Preparation of contaminated monitor surfaces
In the various fields of clean manufacturing such as the food industry, pharmaceutics, coating technology and the semiconductor industry, product quality is essentially determined by the degree of control over particulate contamination. For this reason, controlling particulate contamination on technical surfaces and subsequently cleaning procedures is dependent upon the concentration, size and type of contamination and also upon the material and characteristics of the technical surfaces concerned. One method of determining the effectiveness of detection and cleaning processes is to use calibration surfaces which have been prepared with a defined level of contamination. At present, especially as far as pharmaceutics and the food industry are concerned, no such defined test surfaces are available which cover the relevant influencing parameters of concentration, type and size of particles as well as the type of material and characteristics of surfaces. Test surfaces prepared with biotic particles are required for these industries. Such monitor surfaces can be manufactured for any type, size and concentration of particles. Their implementation simplifies the verification of detection limits as well as the detection accuracy of both test procedures and measurement devices. In addition to this, the effectiveness of costly cleaning and sterilization steps can be investigated and optimized for all the materials used in the manufacturing process and for all the relevant types of contamination concerned. The preperation of calibration surfaces with living micro-organisms is presented in this paper as an application example for developing procedures for the detection of biotic particles in the pharmaceutical industry. Stainless steel, a material which is utilized in clean manufacturing in pharmaceutics and in the food industry, was contaminated with micro-organisms typically encountered in practice and relevant to USP. The development of a suitable sampling system and the determination of relevant process values and parameters are also outlined in this paper.