Formaldehyde, as
a carcinogenic substance, is often intentionally
used to adulterate vegetables to increase their shelf life, and the
adhesive tape used to attach labels can also leave formaldehyde on
the surface of vegetables. However, as the “gold” standard,
gas chromatography (GC) and high-performance liquid chromatography
(HPLC) are expensive for individual tests and confined to the laboratory
owing to their size and a suitable detector (low-cost, portable, fast
detection speed) to check formaldehyde contamination in vegetables
not being available. Here, we tested formaldehyde contamination in
vegetables using a low-cost and hand-held detector combined with a
screen-printed electrode (SPE) amperometric sensor and an open-sourced
potentiostat. The analyzer can detect a concentration of 100 μmol/L
formaldehyde and achieve a good linear range between 100 and 1000
μmol/L. Furthermore, the detector successfully identified formaldehyde
contamination in 53 samples of six different kinds of vegetables even
after residual formaldehyde on the surface was evaporated. Most importantly,
under the practicability-oriented idea, a cost-effective strategy
was implemented for this detector design rather than using other pricey
methods (e.g., photolithography, electron-beam evaporation, chemical
deposition), which enormously reduces the cost (under ∼USD
0.5 per test) and meets all of the requirements of ASSURED device.
We believe this cheap, portable detector could help law-enforcing
authorities, healthcare workers, and customers to screen formaldehyde
contamination easily. Also, the cost-saving strategy is appropriate
for low-income areas, where there is a lack of laboratories, funds,
and trained experts.
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