March 29, 2011 -- A METTLER TOLEDO SevenMulti™ pH Meter has recently been installed at the Fraunhofer Institute for Manufacturing Engineering and Automation (IPA) in Stuttgart, Germany. The Fraunhofer IPA has the cleanest room in the world and the SevenMulti™ is used in it. A pH meter is of course seldom subjected to such extreme environmental conditions. But the SevenMulti™ easily mastered all the applications.
Manufacturing Engineering and Automation IPA
The Fraunhofer-Gesellschaft is one of the leading organizations for applied research in Europe. It undertakes application-oriented research of direct utility to private and public enterprise and of wide benefit to society but does not participate in basic research. The customers are industrial or service companies and the German federal and local government. The 57 Fraunhofer Institutes employ more than 15,000 staff at 40 different locations in Germany. The pH Meter annual research budget totals 1.4 billion Euros. There is very intense international cooperation through the research centers and representative offices in other European countries, the USA, Asia and in the Near East. The institute focuses on areas such as corporate logistics, automation and robotics as well as surface technology. Materials and equipment tested by the Fraunhofer IPA are awarded the “Fraunhofer IPA TESTED DEVICE” certificate. This certifies the clean room capability for the different classes of equipment. Different physical and microbiological tests are performed in order to be able to provide exact information about each tested object or material and award the certificate. Our contact at the Fraunhofer IPA is Markus Keller of the Ultraclean Technology and Micro-Manufacturing Department.
The Super Cleanroom
The Ultraclean Technology and Micro- Manufacturing Department deals with technical questions concerning miniaturized production processes where contamination is a critical issue. These are encountered in branches such as the semiconductor industry, the automotive field and the life sciences. The showpiece in this department is the “cleanest” cleanroom in the world: it is ten times cleaner than ISO Cleanroom Standard Class 1, which is officially the cleanest class. This super cleanroom” operates at overpressure and with a laminar air flow of 0.45 m/s. The climatic conditions are 22 °C and 45 % air/relative humidity. Markus Keller explains, “The SevenMulti™ S47 is sed at the Fraunhofer IPA for different investigations at different places.” The most important tests are:
- Cleanability of surfaces
All surfaces used in hygienic production environments must according to the European Hygienic Engineering & Design Group (EHEDG) be especially easy to clean and disinfect. Polished stainless steel surfaces are considered ideal. To measure the effectiveness of the leaning process, the microbiological bacteria count of the surfaces is measured before and after the cleaning using a surface contact method (Figures 1 and 2). This is performed by pressing a petri dish coated with nutrient agar against the surface with a defined force for 5 seconds. In this test method, the SevenMulti™ and the InLab® Routine Pro pH electrode are used to prepare and set the exact pH of the nutrient agar.
- Metabolization of materials
Under certain climatic and environmental conditions, microorganisms can colonize and propagate on the surfaces of plastics. Their presence can not only damage the plastic but also influence the proper functioning of the components that contain the plastics. To assess the action of microorganisms on materials, the Fraunhofer IPA uses the European EN ISO 846 test standard. The microbiological action on the plastic samples is investigated in a carbon-free nutrient medium. If no growth occurs in the culture medium, then the sample does not contain any nutrients for growth and metabolism can be excluded. The SevenMulti™ S47 two-channel instrument is used to set the pH of the mineral salt stock solution using a sterile 0.01 mol/L NaOH solution.
Other investigations in which the Seven-Multi™ is used are listed below without going into any detail:
- Checking the acidification of rinsing solutions in tests for extractable metals.
- Checking the pH of solvents when washing out pH-unstable organic particles, e.g. precursors of pharmaceuticals, so that these are not dissolved, or to stabilize them.
- Monitoring purified water using the new InLab® 741 and the SevenMulti™ conductivity expansion unit.
- Adjusting buffer solutions, e.g. the potassium phosphate buffer.
The last two applications are usually performed in the cleanroom (Fig. 3). In this case, the SevenMulti™ has to be thoroughly cleaned. This includes cleaning with isopropanol and drying in a flow of pure air.
Markus Keller is happy about things, “Thanks to the dual-channel functionality of the SevenMulti™ S47, we can perform all the pH and conductivity measurements efficiently and very precisely with just one instrument.”
