Preparation of reference materials of total thyroxine

Abstract

Objective To prepare the serum reference materials for total thyroxine. Methods Individual blood samples were collected from 13 healthy donors (7 males and 6 females) aged from 20 to 50 years old, and the sera were separated and mixed into 4 serum pools according to the concentration of thyroxine. The materials were tested for homogeneity and stability using routine methods. The method of isotope dilution liquid chromatography tandem mass spectrometry (ID-LC/MS/MS) was used to determine the concentration of thyroxine. The candidate reference materials were also measured by four conventional methods to analyze the commutability of the materials. Results It showed that the four candidate reference materials were homogeneous and commutable in four conventional methods and they were tested to be stable for at least 1 year at -70 ℃ using the isochronous stability study. The certified values (reference value ± expanded uncertainty, nmol/L) were: 75.9±1.8, 105.3±2.2, 114.7±2.1 and 187.4±2.9. Conclusions Certified reference materials for serum thyroxine have been prepared. These materials have been approved to be the Certificate Reference Materials of GBW 09127, GBW 09128, GBW 09129 and GBW 09130.(Chin J Lab Med, 2016, 39: 40-44) Key words: Thyroxine; Chromatograhy, liquid; Tandem mass spectrometry; Reference standards