Voltammetric Determination of Zinc, Copper, and Selenium in Selected Raw Plant Material

Abstract

The objective of this work was to determine zinc, copper, and selenium content in selected plant raw materials used as pharmaceuticals, foodstuffs, or spices. The study included: Chamomillae anthodium, Anisi fructus, Menthae piperitae folium, Equiseti herba, Urticae folium, quinoa seeds (Chenopodium quinoa), amaranth seeds (Amaranthus cruentus), clove (Syzygium aromaticum), and oregano (Origanum vulgare). Stripping voltammetry with differential pulse step was used for zinc, copper, and selenium determination after microwave digestion procedure for organic matrix decomposition. Obtained results showed that proposed methods were suitable in determination of selenium, copper, and zinc. Selenium content varied from 11.6 µgkg⁻¹ of dry weight of oregano up to 1031.2 µg kg⁻¹ for amaranth. Zinc content ranged from 11.1 to 42.1 mgkg⁻¹ and copper content was between 0.7 and 12.0 mg kg⁻¹. The proposed method was successfully applied and validated by studying the certified reference material (INCT-MPH-2, bovine liver BCR-185), with recovery 94%–102%; 92%–97%; and 97%–108% for copper, zinc, and selenium, respectively.

Keywords:

• Copper
• Raw plant material
• Selenium
• Stripping voltammetry
• Zinc

Acknowledgments

This study was financed as an R&D project by the Polish Ministry of Science of Education from research funds for the years 2007–2010: 15 020 02 and K/ZBW/000552.

Notes

E_acc accumulation potential.

t_acc accumulation time.

dE pulse amplitude.

*ngL⁻¹ (t_acc = 120 s).

SD - standard deviation.

RSD - relative standard deviation.

^a for selenium content [µgkg⁻¹].

^b Concentration below detection limit.