Portable Flow Injection Amperometric Sensor Consisting of Pd Nanochains, Graphene Nanoflakes, and WS<sub>2</sub> Nanosheets for Formaldehyde Detection
Kiattisak Promsuwan, Jenjira Saichanapan, Asamee Soleh, Kasrin Saisahas, Proespichaya Kanatharana, Panote Thavarungkul, Kunanunt Tayayuth, Chunxian Guo, Chang Ming Li, Warakorn Limbut
Abstract
Formaldehyde (FA) is a carcinogenic substance that can be found in various foods. A portable, highly sensitive, and rapid sensor comprising a flow injection amperometric analysis system and an enzyme-free electrode interface is proposed for the determination of FA sampled from foodstuffs. The electrode interface is based on a nanocatalyst of aggregated palladium nanochains anchored on a nanocomposite of graphene nanoflakes and tungsten disulfide nanosheets (PdNC–GNF/WS2). The PdNC–GNF/WS2 electrode directly catalyzes the oxidation of FA at a low applied potential (−0.05 V vs Ag/AgCl) in an alkaline medium. The quantitative determination of FA was performed using a portable flow injection amperometric system connected wirelessly to a portable smart device. Under optimal conditions, the proposed sensor produced linear ranges from 0.010 to 10 mM and 10 to 100 mM with a sensitivity up to 220.6 μA mM–1 cm2. The limit of detection was 0.003 mM (0.10 mg L–1), and sample throughput was 60 samples h–1. The anti-interference characteristics, repeatability, and reproducibility of the sensor toward FA determination were good. The proposed sensor successfully determined FA from food samples, achieving recoveries from 96 ± 4% to 103 ± 3% (n = 3). The obtained analytical performances and results support the potential of the proposed sensor in practical applications.