[Micro-quantitative determination of alpha1-antitrypsin by unidimensional capillary counter-immunodiffusion].

The immunoprecipitation reaction for the determination of microamounts of alpha1-antitrypsin was conducted in the capillaries filled with a microvolume of a 1% agarose gel (the gel length was 7--8 mm, and the diameter--0.6 mm). Microamounts of the antigen and antiserum were applied to the surface of the opposite ends of the gel. Precision control of these manipulations was carried out by means of an ocular micrometer of a binocular lens. The amount of the formed immunoprecipitate in gel was calculated by the summated optic density after staining with amido black recorded by the method of double-wave microspectrophotometry. Sensitivity of the method was 0.3--1.0 ng of alpha1-antitrypsin. The linear plot between the amount of alpha1-antitrypsin and the amount of the precipitate formed was found within the range of 1--25 ng of protein. The error was about 10%.