A new formaldehyde optical sensor: Detecting milk adulteration.

A sensor consisting of an optical fibre with the exposed tip coated with the polyoxometalate salt [(CH)N]H[PMoVO], specially designed to be insoluble in water, which UV-Vis spectrum changed in contact with formaldehyde, is presented. The sensor limit of detection for formaldehyde was 0.2 mg L, and the limit of quantification was 0.6 mg L, which were close to the conventional spectrophotometric method values of 0.2 mg L and 0.5 mg L, respectively, and lower than the tolerable limit for ingested food. The sensor was tested for formaldehyde quantification in milk, as its deliberate addition is a matter of concern. The results obtained analysing formaldehyde in milk samples by the optical sensor and by the conventional method were not statistically different (α = 0.05).