| With the development of world industry and the drastic increase of population, the problem of pollution is becoming more and more serious. More than 18,00 thousand kinds of chemicals have been included in Chemical Abstract,tens of thousands of which have entered our environment. Some data show that about 3 to 4 hundred million tons of poisonous substances enter the environment every year , a lot of which has done great harm to human health and cecological environment .Environmental pollution have been more and more widely concerned by all governments and people of the world. As an important branch science of environment science, the study and usefulness of environment monitor are considered to a considerable degree by researchers of environment. Chemical monitor and apparatus monitor are the prime means in the monitor of quality of environment, and are used widely in the monitor work of micro-pollutant owing to their advantage of high speed and good accurate. One of the characteristics of environment analytical chemistry is to conduct quantitative analysis .Moreover, one of the main directions of the development of environment.analytical chemistry is to improve the sensitivity and selectivity of the analytical method and so is to energetically expand the space to the field of environment science.The fluorescent monitor analytical method is widely used owing to its high sensitivity, fine selectivity, small sampling as well as itssimplicity and high speed .According to the characterist of fluorescent analysis in itself, we developed a serious of researches in the interaction between special effective fluorescent regents and poisonous metals elements.According to Lewis theory of acids and bases and the characteristic structure of R-NH-CS-NH-R', which includes atom of N and atom of S that have the strong capacity of complex and can form steady complex between regents and metal ions. To improve the sensitivity of the regent, we must increase the degree of molecular conjugation and the co-planar effect of regent by introducing salicylaldehyde , 3-Methoxy-4-hydroxybenzaldene and 3-Hydroxy-5-(hydroxymethy1) -2-methy1-iso-nicotinaldehyde at the spot of R when we design its structure, so the fluorescent intensity of the regent are increased remarkably. Under these directions, we used the salicylaldehyde-hydrazinecarbothioamide (SHTA),3-Mcthoxy-4-hydroxybenzaldene-hydrazinecarbothioamide (MHHTA) and 3-Hydroxy-5-(hydroxymethy 1 ) -2-methy 1-iso-nicotinaldehyde Hydrazinecarbothioamide (3-HNHTA) to establish the fluorescent quenching analytical method of Pb,Cd,Tl in food, soil and water. |
