Estimation of performance characteristics of a confirmation method for thyreostats in plasma by means of a weighted least-squares approach

A weighted linear regression-based approach was applied to ascertain analytical performance characteristics of a method for the quantitative determination of thyreostats in plasma by LC-MS. The weights were set equal to the reciprocal of the variances. A straightforward and practical procedure is presented that was used to model the variance of the replicate measurements as a function of concentration. Different function types were tested for their suitability.