Qualitative analysis of Sudan IV in edible palm oil

Sampson Saj Andoh,Tarmo Nuutinen,Matthieu Roussey,Cheetham Mingle

doi:10.1186/s41476-019-0117-0

Abstract

BackgroundPalm oil is one of the most useful vegetable available. Sudan IV dye is used as hue enhancer in palm oil despite the ban as food colorant due to its carcinogenicity and mutagenicity by the International Agency for Research on Cancer (IARC).MethodsSurface enhanced Raman spectroscopy (SERS) coupled with chemometric methods was applied to detect the presence of Sudan IV in some edible palm oil samples.ResultsWe studied the samples within the 1200–1800 cm− 1 Raman frequency range. In predicting adulteration, we used 1388 cm− 1 Raman peak that is associated with Sudan IV as our marker. We were able to confirm adulteration in four of the five palm oil samples provided by the Food and Drug Authority of Ghana.ConclusionsWith these methods, we confirmed the results from Food and Drug Authorities of Ghana by proving that there were indeed Sudan IV adulteration in some palm oil samples.

Highlights

Palm oil is a bright reddish/orange oil produced from the mesocarp of the fruits of the oil palm trees
We used the CH3 band at 1386 cm− 1 in our analysis for adulteration of the palm oil samples
Note a slight shift in the 1386 cm− 1 peak to 1388 cm− 1 in all the oil samples. This could be attributed to the influence of other components in the palm oil samples

Summary

Methods

Chemical reagents and samples All reagents used were of analytical grade. Sudan IV, silver nitrate and sodium chloride were purchased from Sigma-Aldrich A 1 μM stock solution of Sudan IV was prepared in acetone and used in spiking the palm oil to make the in-laboratory prepared samples for measurements. Five edible palm oil samples were obtained from the Food and Drugs Authority (FDA), Ghana. Substrate fabrication A silver-chloride nanoparticulate substrate (AgCl NPs) was prepared according to ref. AgCl NPs were grown on a circular singly polished side silicon wafer (purchased from Smat) by repeatedly and periodically immersing the wafer in two beakers containing 5 mM precursor solutions of silver nitrate (AgNO3) and sodium chloride (NaCl) with 50 cycles of immersions. Principal components analysis was applied to the SERS spectra to generate a graphical plot of the score This was used in establishing the authenticity of the palm oil samples from FDA-Ghana against known adulterated samples.

Introduction

Results and discussion

Conclusion