Formaldehyde can be added illegally as a food preservative in addition to the endogenous
formaldehyde that naturally occurs in aquatic products. In this study, formaldehyde was
derivatized from 2,4-dinitrophenylhydrazine and analyzed using gas chromatographyemass
spectrometry to investigate free and reversibly bound formaldehyde in 10 squid and squid
products. The results were compared to those obtained by high-performance liquid chromatography
(HPLC). The limit of detection was 2.0 mg/kg. The total concentrations of free and
reversibly bound formaldehyde were, on average, higher than the free formaldehyde concentration
by 26.6 mg/kg. Free formaldehyde made up, on average, 39% of total free and
reversibly bound formaldehyde. The sum of the concentrations of free and reversibly bound
formaldehyde was, on average, higher than the free formaldehyde concentration by 19.3 mg/
kg in the HPLC method. Free formaldehyde made up an average of 39% of total free and
reversibly bound formaldehyde in the HPLC method. The use of gas chromatographyemass
spectrometry to detect formaldehyde in aquatic products allowed confirmation through
retention time and molecular mass information. The monitoring of free formaldehyde in
aquatic products and proper control of the manufacturing process could help to reduce the
formaldehyde level in shredded squid products. Finally, exposure to formaldehyde from
consumption of shredded squid was estimated: it was less than 0.2 mg/kg, which is the oral
reference dose suggested by the US Environmental Protection Agency.
