Klaus Danzer

Klaus Danzer is an analytical chemistry researcher who prepared the 1998 IUPAC recommendations on single-component measurement calibration with Lloyd A. Currie. The paper identifies an affiliation at Friedrich Schiller University of Jena, and the NIST publication record gives both authors' full names. The recommendations organize how measured signal is related to the amount or concentration of an analyte under specified conditions.^[ref]

An analytical calibration function separates the response model from its use to infer an unknown. For an original linear example, let concentration $c$ be measured in $mg/L$ and signal $y$ in arbitrary instrument units. Suppose known standards at $c=0,1,2,4$ give $y=2,7,12,22$, exactly satisfyingAn unknown giving $y=17$ has inferred concentration $c=(17-2)/5=3mg/L$. Ignoring the intercept instead gives $17/5=3.4mg/L$, an error of about thirteen percent. A nonzero blank response is not automatically analyte in the unknown.

The same example shows why a calibration curve is more than a unit conversion. A small perturbation of the inverse relation givesReadout variation, uncertainty in the intercept and uncertainty in the slope affect the inferred concentration in different ways. Their covariances can matter when the coefficients are fitted together. These are independently derived sensitivities for the stipulated model, rather than experimental values attributed to Danzer's paper.

A practical calibration measures standards and unknowns with compatible preparation, sample matrix and instrument settings. Repeated standards can reveal measurement noise and time-dependent response; a model established up to $4mg/L$ does not by itself validate its extension to $8mg/L$. The recommendation's explicit dependence on specified conditions makes those experimental choices part of the meaning of calibration, not incidental details.^[ref]

Danzer also coauthored the 2002 distinction between extraction recovery and apparent recovery. That distinction prevents agreement after calibration from being mistaken for proof that no analyte was lost in sample preparation.^[ref]