An interlaboratory comparison of serum total protein analyses.

An analysis of the 1976 CAP Comprehensive Chemistry Survey of total serum proteins is presented. More than 2,000 laboratories contributed data in this survey. Estimation of total serum protein concentration by the biuret reaction remains the most widely used technic, followed by refractometry. Precision and accuracy data for a number of analytic systems and methods are presented. Precisions for the entire group are nearly comparable. A negative bias for total protein concentration was shown by the SMAC.