Comparison of an agarose electrophoresis method and four ion-exchange methods for the measurement of the creatine kinase MB fraction in human serum.

Five CK-MB methods were compared; Corning agarose gel electrophoresis, Worthington CPK Isoenzyme columns, E-C columns, Lancer MB/CPK Isoenzyme, and our own DEAE-cellulose column method. The best precision was obtained with agarose electrophoresis at elevated CK-MB levels. However the agarose electrophoresis method was less sensitive than any of the ion-exchange methods. The detection limit for CK-MB by agarose electrophoresis was variable in the range of 67-17 U/L. A significant bias was shown to exist between the ion-exchange methods and the agarose electrophoresis method. Results by the latter were on the average 4.3, 3.6, 2.7 and 1.4 times greater than CK-MB measurements obtained by the Lancer, E-C, Worthington, and DEAE-cellulose methods, respectively. The bias observed between methods was largely due to the low recoveries of CK-MB activity with the ion-exchange methods; recoveries of 106-122%, 68-78%, 42-44%, 16-19%, and 13-14% were obtained at levels of 18-162 U/L, with the agarose electrophoresis, DEAE-cellulose, Worthington E-C, and Lancer methods, respectively.