Study On The Analytic Technique Of Volatile Organic Compounds In Water-based Coatings

As widely as the coatings have been applied in our daily life, the volatile organic compounds (VOC) contained in coatings have much influnce on our health. During the production process of coatings, a great number of chemicals contain VOCs such as ester ethers, benzoid compounds, aldehydes are used, which will be slowly released in the future after decoration. VOCs not only irritate our skin and respiratory system, but also enter into the blood, and may cause a serious teratogenicity and carcinogenesis. International organizations and national governmental agencies have strict supervision on the VOCs in coating products, and some corresponding regulations have been enacted. The relevant limit conditions and determination methods can be found in GB24410-2009and GB18582-2008.In this paper, the determination of ehtylene glycol ethers and their esters, benzene series and aldehydes in water-borne coatings have been studied respectively. The research achievements show that the detecting methods in this paper not only reduced the limit of detection, but also greatly shortened the detection time-consuming, and will have some theoretical guidance for the determination of VOCs in water-based coatings sold in the market. Three main research contents are included in this paper shown as follows.1. Five ethylene glycol ethers and their esters in water-based coatings were detected simultaneously by the method of gas chromatography-mass spectrometry (GC/MS). While methanol was added to the coating sample to extract the target compund, thoroughly shaken, standing and microfiltrating, then the internal standard solution was added into the filter liquor, and the volume was constanted with methanol, then detected by GC/MS. The conditions of extraction and detection were optimumed; the detection limits of five ethylene glycol ethers and their esters were0.1-1.0mg/kg, the recovery of standard addition was96.46%-101.19%with the relative standard deviation (RSD, n=6) between0.34%and1.89%. The results are indicated that the pretreated method of this detecting process was simple, and the detection limit was low, moreover, the simultaneous determination could greatly reduce the costs of detection, shorten the test cycle. 2. Five benzene series in water-based coatings were detected simultaneously by the metnod of stir bar sorptive extraction-thermal desorption-gas chromatography-mass spectrometry (SBSE/TDS/GC/MS). While sample were extracted with methanol as the solvent, microfiltrated and adsorbed by Twister to reach the adsorption equilibrium, it was desorbed and detected by GC/MS. The detection limits of five benzene series were0.1-0.5μg/kg, the recovery of standard addition was73.16%-115.76%with the relative standard deviation (RSD, n=6) between2.35%and8.13%. The results are revealed that the pretreated method of this detecting process was simple, the detection limit was extremely low, and it has a high sensitivity.3. Six aldehydes in water-based coatings were detected simultaneously by High Performance Liquid Chromatography (HPLC) with pre-column derivatization. Samples were derivatized with2,4-dinitrophenylhydrazine after they were extracted with water, and then analyzed by HPLC. The detection limits of six aldehydes were0.2-4.0mg/kg, the recovery of standard addition was88.8%-112.8%with the relative standard deviation (RSD, n=6) between1.30%and9.54%. This method is simple, and has a low detection limit, high sensitivity, stability and a short inspecting cycle.