Portable Flow Injection Amperometric Sensor Consisting of Pd Nanochains, Graphene Nanoflakes, and WS2 Nanosheets for Formaldehyde Detection

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 mu A mM(-1) cm(2). The limit of detection was 0.003 niM (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.

Automated summary

A portable, highly sensitive, and rapid sensor has been proposed for the determination of carcinogenic substance formaldehyde in food samples. The sensor showed good anti-interference characteristics, repeatability, and reproducibility, and successfully determined formaldehyde concentrations in food samples with high accuracy.