Abstract:
This study aimed to integrate analytical techniques for supporting the safety assessment in food and cosmetics. The two analytical methods were proposed, including i) the development of the paper-based device for the screening detection of lead (Pb) in food matrices, ii) development of the disposable screen-printed electrode for the detection of non-permitted color in halal products. For the first approach, the assay principle was based on competitive binding between carminic acid (CA) and polyethyleneimine (PEI) to Pb in food samples. The reduction of the PEI-CA color distance is proportional to the concentration of Pb. To categorize food which higher or lower the cut-off of the Pb concentration (2 µg·mL−1), the standard addition technique combined with the concept of a drawing PAD was integrated using a series of standard addition (8.0, 9.0, and 10.0 µg·mL−1). The results obtained from the dPAD are in accordance with the concentration measured by the atomic absorption spectroscopy (AAS). The results from the second approach demonstrated that carminic acid and carmoisine were simultaneously assayed under the acidic condition (100 mM sodium citrate buffer, pH 3.0). The electrode was scanned with differential pulse voltammetry (DPV) from −1.5 V to +1.5 V, and by using a bare unmodified electrode, the detection limit was obtained at 33.68 µM. The method was obtained with acceptable precision with 2.78− 9.52 %CVs. We demonstrate the proof-of-concept for the detection of carminic acid in lipsticks. The recovery of > 80% was comparable to those obtained by ultra-high performance liquid chromatography (ultra-HPLC). The recovery study of carminic acid in the beverage and raw material (cosmetic grade) ranged from 101.9% − 123.6% and 93.2% − 109.0%, respectively. Furthermore, to improve the sensitivity of this technique sufficient to detect the CA fortified in actual food samples, the electrode surface was modified with AuNP/PEI composite. Interestingly, the sensitivity was dramatically 24-times improved comparing to the bare electrode. A linear range of 10 – 100 µM (R2 = 0.986) was achieved by using DPV and setting the potential at 0.297 V. In conclusion, an electrochemical method based on a screen-printed electrode modified with AuNP/PEI composite was a promising tool for sensitive detection of carminic acid for assisting the safety monitoring in halal products.
