Application of reference methodology: determination of total protein in serum

A study is described on the calibration of the Technicon SMAC for the determination of total protein. Various results of external quality control programmes showed a bias between our value and the mean mentioned in the survey report. A difference of 4 g/l was found to exist between our calibration value and the value mentioned by the manufacturer. The question arises as to which methodology should be chosen in solving the problems described in this article.