Flame atomic absorption spectrometry combined with surface-modified magnetic mesoporous silica microspheres by polyethyleneimine for enrichment, isolation and determination of Cu²⁺ in preserved eggs after high-temperature digestion

Abstract

A new efficient magnetic solid-phase extractant based on a surface-modified magnetic mesoporous silica microsphere referred as MMSM-PEI was synthesised and used for the enrichment and isolation of copper ions (Cu²⁺) in preserved eggs. The physicochemical properties and morphology of MMSM-PEI were characterized by X-ray diffraction (XRD) spectroscopy, Fourier transform infrared spectroscopy (FT-IR), vibration sample magnetometry (VSM), scanning electron microscopy (SEM) and thermos-gravimetric analyses (TGA). The concentrations of trace Cu²⁺ in the preserved egg were determined by flame atomic absorption spectroscopy (FAAS). The effects of important parameters were examined. The most suitable pH values and temperature for adsorbing Cu²⁺ were 6.5 and 25 °C, respectively. According to the determination of Cu²⁺ in egg white, egg yolk and the outer coating mixture (TOCM) of preserved eggs, the spiked recovery and RSD were 94.1–103.8% and 0.96–4.35%, respectively. The limit of detection (LOD) and the limit of quantitation (LOQ) were 0.14 mg/kg and 0.46 mg/kg, respectively. The developed method improved the sensitivity and accuracy of FAAS for the determination of Cu²⁺ and it could be applied to the determination of trace Cu²⁺ in real samples.

Keywords:

• Preserved eggs
• flame atomic absorption spectroscopy
• magnetic solid-phase extraction
• Cu²⁺ pretreatment

Acknowledgements

The authors are grateful to Xujia Hu for her suggestions for the experiment and writing involved in this article.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (31660437) and the Major Projects of Yunnan Provincial Science and Technology Department(2018ZF004).