Study On The Analytical Methods Of Micro-formaldehyde

The environmental condition has great influence on people's physical and mental health, which has already become general knowledge known by everybody. And the district economic development in our country is uneven. The people in a lot of places can't drink the clean water; breathe the fresh air; eat the sanitary safe food. With the development of social economy and growth of the national power, this kind of condition will be improved to some extent. Strengthening environmental monitoring has positive social and economic meanings in ensuring the social sustainable development of our country. Spectrophotometry, potentiometric titration and oscillating polarography were studied to analyze micro-formaldehyde in mushroom, furan resin, pure water and air. Reaction condition and influence factor were also studied for the determination method in detail.The method of chromotropic acid specrophotometry was improved. Sulfuric acid was replaced by phosphoric acid and hydrogen peroxide. This new method was simple, safe, reliable. The absorbance wavelength, heating time, phosphoric acid consumption, indicator consumption and interference were studied. The Beer's Law was obeyed in concentration range of 0.8~4.8mg/L of formaldehyde. The linear coefficient correlation was 0.9933. The RSD was 2.57%. The proposed method was applied to the determination of formaldehyde in mushrooms. Recoveries were in the range of 92.7~112.0%.The determination of micro-formaldehyde in furan resin with the potentiometric titration was simple, convenient, fast and accurate overcoming the limitation to terminal point of traditional chemical capacity. The standard deviation of this method was 0.11%. The recoveries were in the range of 98.36% ~ 100.86%.The oscillating polarography was applied to determine the formaldehyde in pure water and air. The method for the determination of formaldehyde in the pure water utilized hydrochloric acid for the support electrolyte. Formaldehyde reacted with phenylhydrazine hydrochloride obtaining a sensitive polarographic wave at thepotential of -710mV. The concentration of formaldehyde over the range of 0.05~0.25mg/L was in direct proportion to peak current. The detection limit was 0.002mg/L. Pure water in Times supermarket was determined and, their contents of formaldehyde were less than 0.06mg/L, corresponding to the drinking water standard of the national regulation. The method for the determination of formaldehyde in indoor air used the system of acetic acid-ammonium acetate-acetylacetone as the support electrolyte producing a very sensitive reducing wave at the potential of -1100mV. The concentrations of formaldehyde ranging from 0.01~0.10ug/mL, and 0.1 ~ 1.0|ig/mL were in direct proportion to peak current, and their coefficient correlation were 0.9936 and 0.9959 respectively. Detection limit was 0.002mg/mL.The method was applied to determine formaldehyde concentrations in some laboratories in Nanjing University of Technology. They were in the range of 0.0227—0.1680mg/m3.