Patent ID: 6027570
Filing Date: 2000-02-22
Classification: C11D

Abstract:
A method for cleaning and preventing the buildup of residue on the optical surface of an analyzer for urine which analyzer has such an optical surface through which light passes and which analyzer also is equiipped with a conductive liquid level sensor which method comprises contacting such optical surface with a aqueous formulation comprising1) a quaternary ammonium or phosphonium salt of the formula: ##STR3## wherein R.sub.1 is straight or branched chain alkyl of 7 to 24 carbon atoms; R.sub.2, R.sub.3 and R.sub.4 are lower alkyl of 1 to 4 carbon atoms, X.sup.+ is N or P and Y.sup.- is an anion;2) a non-ionic siirfactant, and3) a divalent ion at a concentration of from 0.05 to 0.7 mM.