Direct determination of selenium in serum by electrothermal atomization laser-induced fluorescence spectrometry

A technique for the determination of serum selenium by electrothermal atomization laser-induced fluorescence (ETA-LIF) spectrometry is discussed. Far-UV radiation used for Se excitation at 196.026 nm was generated as the second anti-Stokes stimulated Raman shift of the output of a frequency doubled dye laser operating near 234 nm. Owing to the high spectral selectivity and high sensitivity of the ETA-LIF technique, direct determination is possible by using a simple aqueous dilution (1:10 or 1:20) of the serum samples and a Pd-Mg chemical modifier to reduce pre-atomization losses of the analyte. The accuracy of the method was demonstrated by analysis of NIST SRM 1598 Inorganic Constituents in Bovine Serum (experimental value 42±3 ng g –1 ; certified value 42.4±3.5 ng g –1 ). Analysis of 128 serum samples drawn from bone marrow transplant patients yielded values of 89±20 and 92±23 ng g –1 for pre- and post-operative samples, respectively.