Sub-part-per-billion determination of total dissolved selenium and selenite in environmental waters by x-ray fluorescence spectrometry

Abstract

The tetravalent and hexavalent selenium content of different environmental water types can be determined after preconcentration on activated carbon by simple energy-dispersive X-ray fluorescence. The elemental selenium Is adsorbed on the activated carbon after specific reduction of the selenite by /-ascorbic acid. The total selenium content is determined after refluxing the water samples with thiourea in sulfuric acid medium and subsequent adsorption of the elemental form. The contribution of hexavalent selenium is obtained by subtraction. All of the experimental reduction reaction parameters have been optimized and the influence of humic material, salts, and oxidizing substances is investigated. The limit of detection is 50 ng L-1 for the tetravalent selenium and 60 ng L~1 for the total selenium content. The coefficient of variation amounts to approximately 10% for both species at the 0.5-1 pg Se L~1 level. The suspended material can easily be analyzed separately.

Photo-induced recovery, optical detection, and separation of noxious SeO32−using a mesoporous nanotube hybrid membrane

“…the water-free SeO 3 2À at the outlet ltrate in the backside region linearly increased with time until saturation was achieved aer 10 min. For this purpose, the following ions were used: 100 ppm alkali and alkaline earth metals (including Na + , Li + , Mg 2+ , Cs + , and Ca 2+ ); equivalent amount (1 ppm) of actively competitive Fe 3+ , Cu 2+ , Ni 2+ , Co 2+ , Pb 2+ , Bi 2+ , and Zn 2+ ions; 10 ppm of trivalent and tetravalent transition elements (Ce 3+ , Sn 4+ , and Ce 4+ ); or even 20 ppm of anion species and surfactant agents such as SDS (CH 3 (CH 2 ) 11 (Fig. 5A), as applied in all of the separation/ltration processes conducted in this study (see Experimental section).…”

“…1-3 Among the polluting species, trace levels (<10 ppb) of toxic anions such as arsenite [As (III) ] are of special concern because of their high toxicological and carcinogenic effects and irreversible damage to human cells. 5,6 Several approaches for selenite detection in biological and environmental samples have been developed, and the commonly used methods for determination and recognition of ultra-trace levels of Se in environmental samples include gas chromatography equipped with a photo-ionization detector (GC-PD), electrochemical and uorescent detection techniques, X-ray uorescence spectrometry (XRF), inductively coupled plasma mass spectrometry (ICP-MS), and ion chromatography (IC)-ICP-MS. [7][8][9][10][11][12][13] Furthermore, considerable efforts have been made to develop simple colorimetric methods for assessment and removal of pollutants by batch adsorption. 4 Regular high intakes of selenite (SeO 3 2À ) can cause serious damage to human health, such as nervous system abnormalities, acute respiratory distress syndrome, hair and nail loss, fatigue, tremors, kidney and cardiac failure, and, in rare cases, death.…”

Water Sample Preservation

“…The effects of pH and storage times were studied and special attention was paid to the effect of the ratio of inner container surface area to sample volume. Robberecht and Van Grieken, 70 using tracer experiments, showed that losses of both selenium(IV) and selenium(VI) from simulated natural waters onto Pyrex and polyethylene containers were negligible even after prolonged storage. This is probably because the selenium is present as oxy-acids, which are partly dissociated, and the anions do not adhere to the container walls.…”

Selective Determination of Selenium(IV) and Selenium(Vl) in Waste Water by Graphite Furnace AAS after Reductive Coprecipitation on Tellurium Collector by Ascorbic Acid, Tin(II) Chloride and Hydrazinium Sulfate

“…Potassium bromide, potassium iodide and thiourea caused positive interference due to the reduction of selenium(VI) to selenium(IV) or elemental selenium by these compounds. 2,12,16 Oxidizing agents such as iron (III) chloride, copper(II) sulfate, potassium iodate and nitric acid interfered with the reductive coprecipitation of selenium(IV) by tin(II) chloride, while the reductive coprecipitation by L-ascorbic acid was not seriously affected.…”