Determination of Total and Inorganic Selenium in Selenium-Enriched Rice, Tea, and Garlic by High-Performance Liquid Chromatography–Inductively Coupled Plasma Mass Spectrometry (HPLC-ICP-MS)

Abstract

The total selenium content of selenium-enriched agricultural products was determined by inductively coupled plasma mass spectrometry after microwave digestion. The total selenium content in the tested samples ranged from 27.9 μg/kg to 13.6 mg/kg. High performance liquid chromatography–inductively coupled plasma mass spectrometry was employed to determine selenite and selenate in selenium-enriched rice, tea, and garlic. The separation of inorganic and organic selenium was realized within 15 min by using 40 mmol/L diammonium phosphate (pH 5.0) and 60 mmol/L diammonium phosphate (pH 6.0) as the mobile phase with gradient elution. Selenite and selenate were isolated by ultrasonic assisted extraction at 78 °C for 30 min with 0.1 mol/L potassium hydroxide as the extraction solution. The detection limits were 2.5 and 5 μg/kg for selenite and selenate, respectively. The relative standard deviation was less than 5.5%. Recoveries of inorganic selenium were between 88.2% and 113.0%. The proposed method was successfully applied for the determination of inorganic selenium as well as total selenium in selenium-enriched rice, tea, and garlic. The results showed that inorganic selenium in natural selenium-enriched agricultural products is primarily present in selenite composing no more than 20% of total selenium.

Keywords:

• High-performance liquid chromatography–inductively coupled plasma mass spectrometry (HPLC-ICP-MS)
• inorganic selenium
• natural selenium-enriched food

Disclosure statement

No potential conflicts of interest are reported by the authors.

Ethical approval

This article does not contain any studies with human participants.

Informed consent

Not applicable.

Additional information

Funding

This work was financially supported by the Ankang Research and Development Center for Se-enriched Products.