Abstract
Background: The goal of this research is to develop a new electroanalytical procedure for the simultaneous electrochemical detection of vitamin K1 (VK1) and vitamin D3 (VD3), in a sodium dodecyl sulfate (SDS) -containing buffer solution, with no detectable interference of other kinds of vitamin A and vitamin E present in the sample solution. Surfactant solutions are well known their capability to dissolve oil-soluble substance such as dyes, hydrocarbons, esters, perfumes, and so on. Micellar solubilization is the powerful alternative for the dissolution of poorly soluble or hydrophobic compounds in aqueous environments. Surfactants micellar media can be successfully applied for the solubilization of lipophilic organic compounds in water media and enhancement of their electrochemical activity. In this research, the anionic surfactant SDS was used as the solubilizing agent.
Method: Poly (Alizarin red S)/multi-walled carbon nanotubes (poly(ARS)/MWCNTs) film was fabricated on glassy carbon electrode and the modified electrode was employed for the simultaneous determination of VK1 and VD3. The peak-to-peak separation for VK1 and VD3 was about 1.0 V in the presence of SDS in 1.5 M ammonium acetate solution (pH 7.0). In this study, the anionic surfactant SDS was used as the solubilizing agent. The peak intensities for the oxidation of VK1 and VD3 increased at poly(ARS)/MWCNTs functionalized electrode and the modified electrode was used for the simultaneous determination of VK1 and VD3. Results: The poly (ARS)/ MWCNTs film on the bare glassy carbon electrode surface was generated by the electrochemical way and then used for the simultaneous quantification of VK1 and VD3 by employing voltammetric techniques. The peak intensity of VK1 was linear with the concentration of VK1 from 0.5 to 80 µM in the presence of 80 µM VD3 and the limit of detection of VK1 was calculated to be 0.06 µM in the presence of VD3. Meanwhile, the peak intensity of VD3 was linear with the concentration of VD3 from 8 to 160 µM with a detection limit of 5 µM in the presence of 10 µM VK1. On the other hand, vitamins A and E did not interfere with the square wave voltammetry response. Conclusion: The suggested method has been successfully implemented for the simultaneous determination of VK1 and VD3 in plant and in milk samples with good precision and accuracy. The constructed poly (ARS)/MWCNTs functionalized electrode showed a simple and multitalented protocol which ensures an effective detection range, low limit of detection, and good potential implementation towards the simultaneous quantification of VK1 and VD3. Adequate recoveries with admissible errors were achieved for the quantification of spiked standard VK1 and VD3 samples in food extracts. Therefore, the developed procedure can be effectively used for the assay of VK1 and VD3 content in real food samples. Further, this procedure could be an alternative method for the simultaneous analysis of VK1 and VD3 in the future with its adequate sensitivity, stability, good reproducibility and it being devoid of matrix interference.Keywords: Vitamin K1, vitamin D3, simultaneous determination, voltammetry, alizarin red S, carbon nanotube, food analysis.
Graphical Abstract
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