Speciation of selenium compounds from high selenium broccoli is affected by the extracting solution

Area of Science:

• Analytical Chemistry
• Food Science
• Environmental Science

Background:

• Selenium speciation is critical for understanding its bioavailability and toxicity.
• High-selenium broccoli presents analytical challenges due to complex selenium compound interactions.

Purpose of the Study:

• To investigate the impact of various extraction conditions on selenium speciation in high-selenium broccoli.
• To determine optimal extraction parameters for accurate selenium analysis.

Main Methods:

• Exploration of 27 extraction conditions using nine buffering systems (pH 1-9).
• Utilized High-Pressure Liquid Chromatography coupled with Inductively Coupled Plasma Mass Spectrometry (HPLC-ICP-MS).
• Analyzed selenium compound polarity using solid-phase extractions and compared retention times with known standards.

Main Results:

• Buffered extractions significantly reduced losses of Se-methylselenocysteine compared to non-buffered methods.
• Approximately 30% of natural selenium was lost via volatilization during buffered extractions.
• Selenium compound polarity and speciation were dependent on pH, buffer type, and the extracting solution, with higher pH favoring oxidized forms.
• Extracted selenium compounds were found to react with the extracting solution, altering their speciation.

Conclusions:

• Extraction conditions profoundly influence selenium speciation and recovery in broccoli.
• Accurate selenium analysis requires extraction conditions that mimic the sample matrix or are clearly defined for specific applications.
• Volatilization and compound transformation are significant challenges in selenium speciation analysis of plant matrices.