Trace selenium levels of the order of 20 g/L are encountered in some neonatal serum samples as a result of selenium deficiency in the mothers or infants diet [9]. Numerous analytical methods [1,5,6,7,9] have been published for the determination of selenium in blood and serum by GFAAS. This study describes the use of new instrumentation and procedures which are important in obtaining the maximum accuracy and precision. Selenium measurement suffers from a number of difficulties: ? The resonance wavelength of 196.0 nm is in the far UV region where both organic and inorganic compounds, likely to be present in the sample, will exhibit molecular absorption. This can be corrected using Zeeman background correction. Selenium in serum measured by Zeeman graphite furnance atomic absorption spectroscopy Application note Authors John Sanders Agilent Technologies, Melbourne, Australia Clinical research 2 ? The intensity of conventional hollow cathode lamps at this wavelength can cause limitations in the precision [6]. Boosted discharge lamps can increase the intensity of the light source, thus lowering noise levels. Selection of special photomultipliers can assist in providing superior response in this region of the spectrum. ? In this complex sample matrix, selenium may exist in any one of a range of chemical species which create atomization problems in the graphite furnace atomizer. This can be overcome by the use of chemical modifiers. ? Selenium is very volatile and can be lost during the ash stage. Suitable modifiers must be used to form compounds with the selenium and allow higher ash temperatures to remove as much of the matrix as possible before the analyte is atomized. 280FS AA 快速序列式火焰原子吸收光譜儀