Determination of Se in Milk with Zeeman- effect Background Corrected Graphite Furnace AAS

Motivation:

Se is an essential as well as a toxic element. The concentration in serum and blood have to be within a small concentration range for optimal health conditions. Other than in human body fluids, where the normal level of Se is close to 100 µg/L, the Se concentration in milk or blood of cows is about a factor of 5 lower. Babies, brought up with cow milk instead of mother milk would therefore develop a dangerous Se deficiency if the infant formula would not be substituted with Se. Analytical control of Se in milk products is therefore of importance. The lowest possible expected value of Se in milk is between 10 and 20 µg/L. This is therefore the required limit of quantification for the analytical laboratory in this type of matrix as well as in body fluids in general.

Zeeman-effect background correction for Se determinations:

Body fluids contain a phosphate which is known to generate structured background at the 196nm Se line. D2 background correction will not handle this problem which will result in a spectral interference and erroneous analytical results. AC Zeeman-effect background correction is able to handle the spectral interference. The determination of Se in undigested body fluids is one of the most challenging applications for GFAAS. It is therefore an excellent example for the analytical quality of a Graphite Furnace Atomic Absorption Spectrometer.