Speciation of selenium compounds with ion-pair reversed-phase liquid chromatography using inductively coupled plasma mass spectrometry as element-specific detection.
For selenium speciation analysis, the hyphenation of chromatographic separation with element-specific detection has proved a useful technique. A powerful separation system, which is capable of resolving several biologically and environmentally important selenium compounds in a single column, is greatly needed. However, that has been difficult to achieve. In this paper eight selenium compounds, namely, selenite [Se(IV)], selenate [Se(VI)], selenocystine (SeCys), selenourea (SeUr), selenomethionine (SeMet), selenoethionine (SeEt), selenocystamine (SeCM) and trimethylselenonium ion (TMSe+), were separated by using mixed ion-pair reagents containing 2.5 mM sodium 1-butanesulfonate and 8 mM tetramethylammonium hydroxide as a mobile phase. The separation of these anionic, cationic and neutral organic selenium compounds on a LiChrosorb RP18 reversed-phase column took only 18 min at a flow-rate of 1.0 ml/min with isocratic elution, and baseline separation among the six organic Se compounds was achieved. Inductively coupled plasma mass spectrometry (ICP-MS) was employed as element-specific detection. A comparison of ICP-MS signal intensity obtained with a Barbington-type nebulizer and with an ultrasonic nebulizer (USN) was made. Different signal enhancement factors were observed for the various selenium compounds when a USN was used. The speciation technique was successfully applied to the study on chemical forms of selenium in a selenium nutritional supplement. Selenomethionine was found to be the predominant constituent of selenium in the supplement.
Zheng
J
J
Department of Applied Chemistry, Chuo University, Tokyo, Japan.
Ohata
M
M
Furuta
N
N
Kosmus
W
W
D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D019587:Dietary Supplements / Q000032:analysis; D013058:Mass Spectrometry / Q000379:methods*; D018036:Selenium Compounds / Q000302:isolation & purification*; D012822:Silicon Dioxide / Q000737:chemistry; D014867:Water / Q000737:chemistry
D018036:Selenium Compounds; D014867:Water; D012822:Silicon Dioxide