title: Standard-suspension-test: influence of bovine albumin, saline and water of standard hardness on M.E.-values.
abstract: Notwithstanding considerable international agreement upon the principle of the quantitative suspension test differences still exist between the main variants of this test, in particular on the diluent to be used in the test mixture. For this reason the influence of the main variables - i.e. bovine albumin (0.03%), NaCl (physiol. saline) and divalent ions (water of standard hardness) - on the activity of the different classes of disinfectants have been investigated. Using so-called borderline concentrations only a small protein effect of 0.03% bovine albumin was found with a phenolic product, quaternary ammonium compounds and aldehydes. A substantial protein effect was observed only with chlorine compounds. The chlorine consumption in the present Dutch Standard Suspension Test is approx. 20 ppm. In tests without a protein load as well as in the presence of 0.03% bovine albumin M.E.-values using saline as the diluent were usually higher than in tests using water of standard hardness (WSH) or distilled water (DW). M.E.-values of quaternary ammonium compounds in WSH were significantly lower than those in DW, presumably due to the antagonizing effect of divalent cations (Mg++ and Ca++). The different views regarding the aim of quantitative suspension tests are discussed. In The Netherlands the opinion prevails that these tests should have at least some relationship with practical conditions. The use of water of standard hardness as a diluent and the incorporation of a slight protein challenge are in agreement with this standpoint.
mesh_terms: D004202:Disinfectants / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects*; D011550:Pseudomonas aeruginosa / Q000187:drug effects*; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects*; D014867:Water / Q000032:analysis
chemical_list: D004202:Disinfectants; D014867:Water; D012710:Serum Albumin, Bovine; D012965:Sodium Chloride