Determination of selenium in human serum by liquid chromatography/electron capture atmospheric pressure chemical ionization mass spectrometry after acid digestion and derivatization using 2,3-diaminonaphthalene

Analysis of selenium in biological samples is very important and numerous analytical methods for the element have been developed. One of the most convenient and widely used methods for routine determination of serum selenium is a fluorometric method using 2,3-diaminonaphthalene (DAN); however, this method lacks specificity. We observed that 4,5-benzopiazselenol (BPS), a selenium derivative of DAN, is ionized with electron capture in an atmospheric pressure chemical ionization (APCI) interface, and subsequently established a method for determining total human serum selenium by means of liquid chromatography/atmospheric pressure chemical ionization mass spectrometry. All pretreatment procedures were carried out in a single test tube to minimize selenium loss. The recovery of organic or inorganic selenium spiked to human serum was 97-103%.The detection limit of BPS was equivalent to 0.2 ng of selenium and the lower quantitative limit of serum selenium was 10 ng mL(-1). The coefficient of variation of standard concentrations in control serum samples was 4.5%. The purity of the observed peak obtained from serum samples was confirmed using the ion cluster technique.