Online preconcentration-IC-ICP-MS for selenium quantification and speciation at ultratraces

Area of Science:

• Environmental Science
• Analytical Chemistry
• Human Health

Background:

• Selenium (Se) is vital for human health, but optimal dietary intake occurs within a narrow range.
• Analyzing selenium speciation in deficient environments is challenging due to low natural abundance and analytical difficulties.
• Existing methods lack the sensitivity and accuracy for ultratrace selenium speciation analysis.

Purpose of the Study:

• To develop a novel, highly sensitive method for determining selenium species at ultratrace levels.
• To quantify selenite (Se(IV)) and selenate (Se(VI)) in environmentally relevant samples.
• To assess the applicability of the method for selenium-deficient environmental matrices.

Main Methods:

• Online coupling of a preconcentration (trap) column with an ion chromatography inductively coupled plasma mass spectrometry (IC-ICP-MS) system.
• Quantification of selenite and selenate down to picogram levels.
• Analysis of pristine volcanic ash samples from diverse geographical locations.

Main Results:

• The developed method achieved ultratrace quantification of Se(IV) and Se(VI) down to 7.3 and 8.3 pg Se, respectively, within 420 seconds.
• Successful speciation analysis was demonstrated in selenium-depleted volcanic ash samples (<0.05 mg kg(-1) Se).
• Significant variations in selenium speciation (co-occurrence of selenite and selenate) were observed across samples with diverse chemical compositions and pH.

Conclusions:

• The novel IC-ICP-MS method offers a robust, efficient, and highly sensitive approach for selenium speciation at ultratrace levels.
• This technique overcomes previous limitations in analyzing selenium-deficient environments.
• The method's versatility is highlighted by its successful application to environmental samples with wide-ranging pH and ionic compositions, indicating broad applicability.