SELENIUM SPECIATION
Selenium can be presented in both inorganic (selenite, selenate, hydrogen selenide etc) and organic forms (selenomethionine, selenocysteine and selenoproteins etc). Among them, hydrogen selenide is extremely toxic while selenomethionine is essential and nutritional to the human body. The forms and the concentrations of selenium define its role in the environment and in the living systems.
The field of selenium speciation has been receiving increasing attention over the past decades. Research and routine analysis of selenium is undertaken in plants, soils, nutritional supplements, and biological samples (urine etc.) in many environmental institutions and agencies.
PSA 10.825 ISOCRATIC LC SYSTEM USED IN CONJUNCTION WITH THE PSA MILLENNIUM EXCALIBUR FOR THE SPECIATION OF SELENIUM
The PSA 10.055 Millennium Excalibur system can easily be utilised for Selenium speciation by the simple addition of a liquid chromatography system and a PSA 10.570 UV oxidation unit. Using a reverse phase column with a modifier of DDAB, five selenium species (selenocystine, selenomethionine, selenoethionine, selenite and selenate) can be generated in under 10 minutes. This system can be used for the speciation of selenium in water, urine and food samples, allowing sub ng ml-1 detection limits to be obtained after suitable extraction
The inclusion of the UV system aids in the conversion of the species into hydride forming species thus allowing lower limits of detection to be achieved.
Typical limits of detection of 0.1 ng ml-1 are readily achievable. Excellent sensitivity and reproducibility combine with ease of use and a small footprint to offer a reliable and effective means of selenium speciation.
The system consists of a 1200 series Isocratic pump, manual injection valve and solvent cabinet. With the simple addition of the correct column, the analyser and hand held are ready to run.
The 1200 series
pump is made of robust materials to withstand the most demanding
of applications; stainless steel, titanium, gold, ruby, sapphire,
ceramics, PEEK and PTFE. The seal wash option for high salt mobile
phases keeps maintenance to a minimum, thereby providing lower
operational costs.
The system can be enhanced by the C723I009 ChemStation base software. This software is the industries' most widely sold data system, handling all applications including LC, LC/MS, GC, CE and CE/MS. This base provides the ideal platform for labs that need an easy-to-learn and easy-to-use system, which can be scaled up and extended as the laboratory's needs grow.
Chromatogram of five Selenium species obtained using HPLC-UV-HG-AFS
Five Selenium species; (SelenoCysteine, Selenite, SelenoMethionine, SelenoSugar-1 and Selenate) were separated using 40mM ammonium formate, 0.01 mmol l-1 DDAB, 0.5% (v/v) methanol, pH 4 as mobile phase at 0.8 ml min-1 on a C18 column (PSA C2 or equivalent) and then digested by online UV irradiation at elevated temperature.
Hydride generation was used as sample introduction technique, and this was maximized for all species by the optimization of variable analytical parameter. The final optimized conditions for UV-HG-AFS were 50% (v/v) HCl + 5% (m/v) KBr as reducing reagent, 0.8% (m/v) NaBH4 in 1% (m/v) NaOH as reductant, 250ml min-1 argon flow rate and 150°C temperature.
To discuss particular requirements and for more detailed information on the above product please complete the Information Request Form.
For information on the speciation of other elements please follow the appropriate link below:
