Abstract: Sodium formaldehyde sulfoxylate can break down into formaldehyde and sulfur dioxide in process of using. First, the contents of the formaldehyde in food were determined by fuchsine-sulphurousacid spectrophotometry and the sulphur dioxide samples were determined by pararosaniline hydrochloride method. Then the mass ratio of the formaldehyde to the sulphur dioxide was calculated, If the mass ratio is near 1:2.1, sodium formaldehyde sulfoxylate exists in samples. The fast sample preparation method was developed. The linearity, precision and recovery of the method were evaluated. The experimental results proved it may be applied to determine actual samples.

Key words: food, sodium formaldehyde sulfoxylate, formaldehyde, sulfite, spectrophotometry