Determination of Harmful Substance Formaldehyde in Water-soluble Coatings and Evaluation of the Measurement Uncertainty

UV spectrophtometric analysis method with acetylacetone as color developing reagent, for determination of formaldehyde in water-soluble coatings are studied in details. The results of the study show that the calibration curve of the method has good stability. The relative standard deviation of the slope of calibration curves is 0.74% . Some notices should be taken in sample preparation: a) water volume added to the coating sample should be more than 200 mL before separating formaldehyde from solid sample by distillation, b) after distillation, the volume of remnant of coating sample and water mixture should be less than 5 mL, c) the formaldehyde in distillation solution should be determined at the same day. The experiments also show that the mean recoveries for high and low levels of formaldehyde in coatings are 98.5% and 87.9%, respectively. The uncertainties of analysis results are also estimated.