A novel single step method to rapidly screen for metal contaminants in beverages, a case study with aluminum

Portable electroanalytical devices for metal ion sensing towards assessing food quality is an emerging high impact research area. Herein, we demonstrated for the first time, a portable electrochemical platform to measure the threshold aluminum content in packaged acidic food products. The sensor consists of a gold screen printed electrode (Au-SPE) modified with the exfoliated Pd/C catalyst (5% Pd on vulcan carbon). The electrochemical activity of the Pd/C catalyst modified Au-SPE electrode, influenced by the added/spiked Al (III) ions in the range 5 μg/mL–1000 μg/mL was analyzed using Electrochemical impedance spectroscopy (EIS) in two buffer media of citrate and ascorbic acid in the pH 3.5 and 4.5. The sensor was further tested for the Al(III) ions doses spiked in real fruit samples viz. canned tomato juice (pH 4.2) and the orange juice (pH 3.5). The sensor showed sensitivity in the concentration 5 μg/mL–1000 μg/mL (linear response 5–100 μg/mL) with the limit of detection (LOD) of 5 μg/mL. The modified sensor is selective with respect to the common interfering monovalent and divalent cations present in the juice samples viz. Na+, K+ and Ca2＋. To validate the possible translation to the portable device, the performance of the sensor was then tested using portable electrochemical device for spiked Al (III) ions doses in tomato juice, which showed a correlation (Pearson’s) r of 0.95 when compared to the laboratory benchtop method (Gamry instrument). An electroanalytical tool developed using this testing approach can be an efficient and accurate qualitative testing method for Aluminum poisoning and alternate metals in common food products.