Table 1.
Relative bias: The difference (in%) between the mean value of the same systems in 3 labortories and the target value of the RM; *the bias (bias>3.4%) exceeded the minimal quality specifications.
Abbreviations: HK, hexokinase; GOD, glucose oxidase; POD, peroxidase; G6PD, glucose-6-phosphate dehydrogenase; ID-MS, isotope dilution-mass spectrometry; RM, reference material.