Pitfalls of the Microtiter System for Serial Dilutions and Standardization Using Radioiodinated Albumin

The hemagglutination inhibition immunoassay and the staphylococcal clumping technic for determining fibrinolytic split products both utilize the microtiter system. The quality control of this system, using 131I-labeled albumin, is described. Three dropper pipettes were found to have errors, based on an expected volume of 25 µl., of –7.6 to 14.4% (mean 3.5%). Eight transfer pipettes were found to contain volumes larger than the expected 25 µl.; the errors ranged from 6.4 to 14.0% (mean 9.9%). The proper use of the microtiter system and the accuracy of doubling dilutions are discussed. The technic has inherent pitfalls but, if performed properly, gives reproducible results.