Simultaneous determination of selenite and trimethylselenonium ions in urine by anion exchange chromatography and molecular neutron activation analysis

Abstract

A method has been developed for the determination of trimethylselenonium (TMSe) Ion and selenite (Se032™) Ion In urine by anion exchange chromatography, selectively eluting TMSe and Se032'. Since the recoveries are quantitative, a method of additive spikes Is employed to determine TMSe and Se032" Ion concentrations In urine specimens. The TMSe and Se032-chromatographic elutions were collected In vials, Irradiated with neutrons, and radloassayed for 77mSe activity. The limit of detection Is 10 ng of Se as TMSe or Se032"/mL of urine. Thirteen urine specimens from normal subjects were analyzed for TMSe, Se032™, and total selenium concentration.

Selenium Metabolites in Urine: A Critical Overview of Past Work and Current Status

“…They were also the first to report TMSe in normal human urine (i.e., without selenium supplementation). The data, however, were variable; in one report (25 ) they claimed that TMSe constituted ϳ30% of the total selenium in normal urine, whereas in two other very similar studies (26,28 ), they reported up to 90% TMSe in normal urine.…”

“…Blotcky and coworkers (25,26,28 ) were especially conspicuous in this area with several publications focusing on determining TMSe with use of neutron activation analysis for detection. They were also the first to report TMSe in normal human urine (i.e., without selenium supplementation).…”

“…There are two exceptions, however. One study (26 ) reported selenite in 4 of 13 urine samples at up to 95% of total selenium. The method (ion-exchange chromatography with off-line detection), however, seems rather nonselective for selenite, and the data must be questioned.…”

“…Despite this anomaly, TMSe was regarded as a major selenium urinary metabolite and was generally thought to increase when selenium exposure was above nutritional requirements. Unknown selenium species were also reported in urine, but the only other known selenium species claimed to be in urine were selenite (26,28,53 ) and selenodiglutathione (53 ). After the introduction and application of HPLC/ ICPMS for the determination of selenium urinary species, one may have anticipated that TMSe would be regularly reported as a major metabolite.…”

The identification of selenium species in biological samples

“…128,129 In all cases trimethylselenonium ion was detectable, but it now seems generally accepted that this ionic species is a major metabolite only when intake of selenium is high. 121,130 Electrothermal atomic absorption spectroscopy (AAS) 131 and molecular neutron activation analysis [132][133][134][135] have been used to analyse metabolites of selenium, including trimethylselenonium ion, in human urine following separation by ion-exchange chromatography. Selenite and selenate in human urine have also been analysed by ICP-AES following separation by a resin complexation method.…”