Study On The Determination Of Formaldehyde In Water-borne Coatings

With the rapid development of economy and the continuous improvement of living standard, the interior decoration is becoming a kind of fashion. people enjoy a comfortable family life but at the same time people face more and more air pollution problem. At present, formaldehyde is one of the most serious pollutant. Formaldehyde has important influence on human health. The toxicity of formaldehyde is mainly irritate to eyes, respiratory and skin which can lead to tears, nausea, sickness, bosom frowsty, general malaise and other symptoms. Long time contacting formaldehyde can cause chronic respiratory disease, memory loss, chromosome abnormality and immune dysfunction. The World Health Organization (WHO) and The U.S.Environmental Protection Agency (US EPA) list formaldehyde as a potential danger carcinogen and important environmental pollutant. Water-borne coatings are one of the important source of formaldehyde. Therefore, the determination of formaldehyde in water-borne coatings will be very important to reduce indoor pollution.At present there are many methods which were applied to the determination of formaldehyde in water-borne coatings, but because the sample matrix are very complex and diverse, these methods have some problems such as the influence of interference composition. They are time-consuming, operation trival, poor selective and low sensitivity, therefore, it is necessary to study a simple, rapid, accurate method to analysis free-formaldehyde in water-borne coatings.A method for the determination of free-formaldehyde in water-borne coatings by high performance liquid chromatography (HPLC) after devivatization to 2, 4- dinitrophenylhydazone was developed in the paper. In the course of the test, the effect factories on the devivatizing reaction and the conditions of high performance liquid chromatography separation are investigated and optimized. Also the uncertainty in determination of free-formaldehyde in water-borne coatings by high performance liquid chromatography was evaluated. This major content and the major viewpoint of this paper as follows:(1) The sample pretreatment method was studied, The water-borne coatings which have various properties were collected and preliminary classified. The sample reaction system and derivative conditions of formaldehyde were investigated and optimized. Sample was diluted by water and derived with 2, 4-dinitrophenylhydazine under acidic condition in methanol solution, at 60℃for 30 min, no need of organic solvent extraction, then analysed by high performance liquid chromatography.(2) A method for the determination of free-formaldehyde in water-borne coatings by high performance liquid chromatography was developed. Chromatographic conditions such as mobile phase , determination wavelength were optimized. Liquid chromatography separation is performed on a C18 column .Analyses are detected using Photodiode Array Detector (DAD) at the wavelength of 354 nm. The mobile phase is acetonitril /water (65/35) at a flow rate of 1.0 mL/min. The quantity of the compoud is determinated by the calibration curve. The calibration curve is linear in the rang of 0.1 mg/L - 5.0 mg/L with correlation coefficient R2 is 0.9997. The regression equations is y=310.96x-7.41 for formaldehyde. This method has higher sensitivity, reproducibility and accuracy. Under the optimal conditions, The detection limits of the method is 0.99 mg/kg. The recovery of formaldehyde at two spiked concentration levels of 0.4 mg/L and 2 mg/L vary from 84.2% to 92.5%, with relative standard deviation (RSD) not more than 5%.(3) The uncertainty in determination of formaldehyde in water-borne coatings by high performance liquid chromatography was evaluated. The factors affecting the uncertainty in determination was analyzed and assessed in detail. The standard expression of measurement were given. The uncertainty mainly derives from the standard curve and repeated measurements, etc.(4) High performance liquid chromatography and acetylacetone spectrophotometry two analysis methods were compared. The influence of two analysis methods to the determination results for different types of samples was studied.