Sub-millimolar determination of formalin by pulsed amperometric detection [An article from: Analytica Chimica Acta]

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Description:
Formalin, formaldehyde in the presence of methanol, was determined by pulsed amperometric detection (PAD). A triple waveform using E"d"e"t=-0.3V (t"d"e"t=30ms), E"o"x"d=+0.8V (t"o"x"d=200ms), and E"r"e"d=-0.8V (t"r"e"d=350ms) versus Ag/AgCl was applied at a Au electrode for detection in a flow injection (FI) system. The approach was rapid and yielded a sub-millimolar detection limit (0.0129mM) with a dynamic range up to 100mM. A precision of 8.8% R.S.D. at 1.0mM for two hundred repetitive injections by the FI-PAD was obtained, whereas holding at a constant potential (-0.3V versus Ag/AgCl) for anodic oxidation of formaldehyde caused the response to decrease dramatically after a few measurements. The method developed was used to analyze the formalin contents of water from rinsed samples of vegetables and fruit and ice-melt from seafood, and the method showed good agreement with the liquid chromatography (LC) method.