Abstract: Objective To investigate the feasibility of freezing admixing human serum which was the selected standard materials of gamma-glutamyltransferase(GGT), and to observe and analyze their stability at -80 ℃. Methods The GGT serum which had been collected was mixed, filtered and subpackaged according to five levels. Then the selected standard materials were measured at 0, 7, 30, 60, 120, 180, 330, 360, 390 and 750 days. In order to evaluate the stability, the results were statistic analyzed by linear regression. Results In the 750d, the P of the linear regression about C1~C5 was more than 0.05(the P of C1~C5 was 0.886, 0.753, 0.585, 0.571 and 0.945). Conclusion The preparation method of the freezing admixing human serum which was the selected standard materials of GGT was simple and convenient, otherwise the stability of the selected standard materials was well in 750 days.

Key words: gamma-glutamyltransferase, reference material, stability