A. Buursma

A. Buursma collaborated with W. G. Zijlstra and W. P. Meeuwsen-van der Roest on experimental reference spectra for hemoglobin derivatives. Their 1991 paper measured molar absorption coefficients for fetal and adult forms of the oxygenated, deoxygenated, carbon-monoxide-bound and oxidized derivatives.^[ref] Such measurements support quantitative optical analysis of mixtures, including co-oximetry.

The measurement problem can be expressed through the Beer-Lambert law. For a transparent mixture with a known path length $l$, a simple linear model at wavelength ${\lambda }_j$ isHere $A_j$ is absorbance, $c_k$ are component concentrations and ${\epsilon }_{jk}$ are reference molar absorption coefficients. The reference experiment provides coefficients; the later mixture experiment measures the $A_j$. These are distinct roles in the analysis.

An original example illustrates why multiple independent readings are useful. With normalized coefficients, let $A_1=c_1+2c_2$ and $A_2=2c_1+c_2$. Measurements $A_1=A_2=3$ imply $c_1=c_2=1$. With only the first reading, both $(c_1,c_2)=(1,1)$ and $(3,0)$ fit. Additional readings help only when their coefficient rows supply linear independence; repeating the same equation more precisely does not identify both concentrations.

The example explains the importance of reliable reference coefficients without attributing an unreported individual laboratory task to A. Buursma. The verified scientific contribution is coauthorship of the experimental spectral dataset.