Method for detection and determination of human serum albumin

A method for optical detection and quantitative determination of human serum albumin or HSA in biological liquids comprising the steps of

• a) providing a sample of a biological liquid containing human serum albumin or HSA;
• b) adding to the sample an anionic cyanine dye of general formula (1) ##STR8## where n means 0 or 1;
• M.sup.+ is any monovalent cation;
• R.sup.0 is cyano, aryl, or COR where R stands for alkoxy, alkyl or aryl;
• R.sup.1 is cyano, aryl, or COR where R stands for alkoxy, alkyl, or aryl;
• R.sup.2, R.sup.8 each stand for hydrogen, alkyl, or cyano;
• R.sup.3, R.sup.5, R.sup.6, R.sup.7 each stand for hydrogen or alkyl;
• R.sup.4 stands for hydrogen, halogen, alkyl, aryl, aryloxy, alkoxy, or NR.sub.2 where R stands for alkyl or aryl;
• R.sup.9 stands for cyano, aryl, COR where R stands for alkoxy, alkyl, or aryl, CO-NAB where A stands for alkyl, aryl, or carbamoyl and B stands for alkyl or aryl, hydrogen, or heterocyclyl;
• R.sup.10 stands for cyano, aryl, COR where R stands for alkoxy, alkyl, or aryl, CO-NAB where A stands for alkyl, aryl or carbamoyl, and B stands for alkyl or aryl, hydrogen, or heterocyclyl;
• and where at least one substituent of R.sup.0, R.sup.1, R.sup.9 or R.sup.10 stands for cyano;
• c) measuring the increase in fluorescence intensity, or the change in fluorescence polarization, or the change in fluorescence lifetime of the dye, or the change in absorption of the dye as a result of binding of HSA to the dye;
• and
• d) relating the change in fluorescence or absorption to the actual amount of HSA in the sample.