Multivariate optimisation of an ultrasound assisted-matrix solid-phase dispersion method combined with LC-fluorescence detection for simultaneous extraction and determination of aflatoxins in pistachio nut samples

Abstract

This paper describes the application of ultrasound-assisted matrix solid-phase dispersion as an extraction and clean-up procedure for aflatoxins (B₁, B₂, G₁ and G₂) and subsequent determination by LC-fluorescence detection. A Box–Behnken design was used to determine the parameters influencing the extraction procedure through response surface methodology and experimental design. The influence of different variables including type of dispersing phase, sample-to-dispersing phase ratio, type and quantity of clean-up phase, ultrasonication time, ultrasonication temperature, nature and volume of the elution solvent were investigated in the optimisation study. C18, graphitic carbon black and acetonitrile were selected as dispersing phase, clean-up phase and elution solvent, respectively. The optimised values were sample-to-dispersing phase ratio of 1:1, 50 mg of graphitic carbon black, 11 min ultrasonication time, 30°C ultrasonication temperature and 3 ml acetonitrile. Under the optimal conditions the limits of detection (LODs) were ranged from 0.04–0.11 µg kg⁻¹ and the relative standard deviations (RSDs) of the extraction method were less than 8.6%. The recoveries of the matrix solid-phase dispersion process ranged from 74% to 78% with relative standard deviation lower than 9% in all cases. Finally, the matrix solid-phase dispersion was successfully applied to extraction of trace amounts of aflatoxins in pistachio samples.

Graphical abstract

Keywords:

• ultrasound-assisted matrix solid-phase dispersion
• aflatoxins
• multivariate optimisation
• pistachio nut samples

Acknowledgments

Pirayeh Zist laboratory (Qazvin, Iran) is acknowledged for technical support. This paper does not contain any studies with human or animal subjects.

Funding

The authors are thankful for the financial  support from the Central Tehran Branch, Islamic Azad University through its “determination of aflatoxins in pistachio nut samples ultrasound assisted-matrix solid phase dispersion method”, Project 2011/23/09.