Flourescence-assay on traces of protein on re-usable medical devices: cleaning efficiency

The cleaning of re-usable medical devices before disinfection or sterilization is recognized as being an essential phase. Detection of residual proteins can be used to validate the process, provided a sufficiently sensitive method is employed. A fluorescent method is presented, using orthophtalaldehyde (OPA) bound to N,N dimethyl-2-mercaptoethylammonium, to demonstrate the presence of amino acids on a medical device following cleaning. The sensitivity of this method (10-5 g/l) was assessed and the applicability of this detection technique is verified, using three types of carriers (steel blades, glass tubes or ceramic penicylinders), three types of contaminants (yeast extract, bovine albumin with native sheep's blood and formaldehyde fixed fibrin). In this context, studies involving formaldehyde-fixed fibrin are more sensitive and are to be recommended.