Determination Of Pb And Phosphate In Environmental Water By Double Wavelength Spectrophotometry

Metal pollution and eutrophic water pollution are always the key point of water enviromental monitoring. With cumulation and polyaffinity,lead is toxicant which was taken to human body by diet and drinking.China clearly stipulated the content of Pb in potable water must not exceed 10μg/L. Phosphonium which is one of the essential elements of biological growth,will lead to eutrophic water pollution by excessive multiplication.Therefore,it has momentous social significance of studying on monitoring and analyzing the content of lead and phosphate in enviromental water.In part 1,the development trend, research status and the harm to human being or enviroment of lead and Phosphate were summarized respectively.Based on the aboved results,the new methods for determination of Pb and phosphate were then established.In part 2, the reaction between Pb2+and Xylenol Orange (XO) was studied at pH 5.8 in HAc-NaAc buffer. The new method named as Double peak double wavelength spectrophotometry(DPDWS) was applied instead of single-wavelength method for the determination of Pb based on the above-mentioned reaction.It was sensitive and selective with the presence of sulfocarbamide and ammonium citrate. The results show that the maximum adsorption wavelength of the reagent and the complex compound are 435 nm and 575 nm,respectively. As the concentration of Pb in the range of 0.168μg/mL-2.5μg/mL,the absorbency accords with the Beer's law well. And the DL was lower to 0.05μg/mL. The molar adsorption coefficient of this methodεis 2.458×104 L·mol ^-1·cm^-1,which enhances 2 times than that of the single wavelength method which molar adsorption coefficientεis 1.191×104 L·mol^-1·cm^-1 ,By analyzing several samples,the RSDs were less than 2.55% and the recovery rate of Pb was between 95.04%-99.85%.In part 3,the reaction between Pb2+and Xylenol Orange (XO) was studied at pH 5.8 in HAc-NaAc buffer.It was sensitive and selective with the presence of sulfocarbamide and ammonium citrate. The new method named as primary-secondary wavelength spectrophotometry (PSWS) was applied instead of single-wavelength method for the determination of Pb based on the above-mentioned reaction. Results showed that such a method resulted in a good precision and high accuracy,the calculated curve was very stable.Within the range of 0.022μg/mL-2.5μg/mL,the parameter logy was linear with logc and the DL was lower (0.007μg/mL).By analyzing several samples,the RSDs were less than 1.67% and the recovery rate of Pb was between 98.79%^-107.6%.In part 4,the reaction system of PO₄^3--Mo₇O₂₄^6--Sn²⁺ was sensitive and selective at pH 1.5-2.5.The new method named as primary-secondary wavelength spectrophotometry (PSWS) was applied for the determination of PO₄^3- based on the above-mentioned reaction system. Results showed that such a method resulted in a good precision and high accuracy,the calculated curve was very stable.Within the range of 0.012μg/mL-0.4μg/mL,the parameter logy was linear with logc and the DL was 0.004μg/mL.By analyzing several samples,the RSDs were less than 5.67% and the recovery rate of PO₄^3- was between 96.4%^-100.7%.The method was suitable to be used and spreaded in departments of basement layer for its bright development prospect.