The use of radiofrequency glow discharge-mass spectrometry (rf-GD-MS) coupled to gas chromatography for the determination of selenoaminoacids in biological samples
Mm. Bayon et al., The use of radiofrequency glow discharge-mass spectrometry (rf-GD-MS) coupled to gas chromatography for the determination of selenoaminoacids in biological samples, J ANAL ATOM, 16(5), 2001, pp. 492-497
A radiofrequency glow discharge (rf-GD) has been used as an ion source for
mass spectrometry using gas chromatography as the sample introduction techn
ique for the speciation of seleno amino acids. The use of helium as the pla
sma gas allowed the monitoring of selenium's major isotope (Se-80), interfe
red by polyatomic species when using Ar as the plasma gas. Optimization of
the power and pressure of the source was undertaken to achieve the best sen
sitivity for selenium determination and detection limits of about 100 pg (a
s Se) have been obtained for the derivatized Se-methionine. Studying the ce
ll pressure and power on the fragmentation patterns obtained for Se-methion
ine and Se-ethionine has also been undertaken to characterize the source. N
o significant variations were observed on the mass spectra under different
operating conditions, although noticeable variation of the fragment intensi
ties was observed. The system has been applied to the determination of Se-m
ethionine in selenium-enriched yeast after enzymatic extraction of the corr
esponding species using Proteinase K to cleave the peptide bonds. The resul
ts obtained showed a Se-methionine content of about 78% in the enriched yea
st.