Spectrophotometric determination of formaldehyde in leather samples with chromotropic acid by flow injection analysis

A highly sensitivity and relatively interference-free spectrometric method is described for the determination of formaldehyde in leather, which is based on its reaction with chromotropic acid in the medium of 0.4 mol/L sulfuric acid medium to form a complex. The absorbance of the complex was measured spectrophotometrically at 390 nm, the stabilization of the complex was not less than 96 h. The chemical factors and FIA variables affecting the system were also examined, including various solvent, reaction time, and so on. The detection limit was 0.1 mu g/L calculated from three times the average background noise. The linearity concentration range of the correlation curve was from 0.05 to 10 mg/L of standard solutions. And the relative standard deviation was 0.6% (n = 11) obtained by injecting 500 mu g/L standard formaldehyde solution. The proposed method was successfully applied to determine formaldehyde in leather.