Determination Of Chromium, Copper And Total Phosphorus In Water Environment By Sequential Injection-spectrophotometry

Recently, the heavy metal pollution and eutrophication events in water environment havereceived extensive attention. The monitoring of water quality has become an issue of vitalimportance. Therefore, the development of a series of reliable on-line analyzers, which is toimplement on-line automatic monitoring of the heavy metals and nutrients in surface water,industrial wastewater and domestic sewage etc., is an ever growing challenge. In this paper,spectrophotometric analysis has been carried out on a Sequential Injection Analysis-Lab OnValve(SI-LOV) platform aiming at on-line automatic monitoring. The determination of theheavy metal ions Cr(Ⅵ), Cu(Ⅱ) and Total Phosphorus (TP) has been carried out bysequential flow injection-spectrophotometric methods，and the impact of a variety of testconditions on the relationship between the conditional parameters and absorbance have beeninvestigated. With sequential flow injection analysis, determination of Cr(Ⅵ), Cu(Ⅱ) can beperformed more quickly with lower regent consumption. Based on the method of Systea andSkalar on-line analyzer for TP measurement in water environment, the method for TP rapidanalysis has been established on a newly building Sequential Injection Analysis-Lab On Valveplatform. The main contents are as follows:1,Based on determining of Cr(Ⅵ) in the sequential injection platform, the results werecompared with GB/T7467-1987test in order to optimize this system. In acidic medium,Cr(Ⅵ) was detected by chromogenic agent DPC.The photometric detection used540nmwavelength, and the product of Cr(Ⅵ) was purple chromium-phenylazo carbohydrazidecomplexes in the reaction mixture of phosphoric acid and sulfuric acid solution.Determination of optimal conditions containing the interfering ions of Hg2+, Mo6+and Fe3+.The method has been used to detect the concentration of Cr(Ⅵ) in water samples withtechnical satisfactory.2,Based on the above experiment, we built on a Sequential Injection-Lab On Valve laboratoryplatform to test the heavy metals in the online absorbance assay of Cr(Ⅵ) and Cu(Ⅱ). Cr(Ⅵ)was detected by DPC as chromogenic agent. The product of Cr(Ⅵ) purple chromiumcompounds-phenylazo carbohydrazide complexes in0.6mol/L sulfuric acid solution can bedetected by543nm wavelength photometric detection; And using zinc reagent with a purple complex product, determination of Cu(Ⅱ) has been carried out in the Clark-Lubs buffersolution (pH7.6) with600nm wavelength photometric testing. Under optimal conditions, theCr(Ⅵ) and Cu(Ⅱ) in actual water samples can be measured with better accuracy comparedwith the GB measurement.3, Based on the method of Systea and Skalar on-line analyzer for TP measurement in waterenvironment, on the Sequential Injection-Lab On Valve(SI-LOV) systems, TP has beendetected by spectrophotometry with ammonium molybdate as chromogenic agent.The analysis conditions of sequential injection spectrophotometry have been optimized.Blue complexes produced by the phosphomolybdic heteropoly acid reacting with ascorbicacid can be detected with880nm wavelength. Under the optimal conditions, linearrelationship between values of absorbance and mass concentration of TP has been obtained inthe range within0.10-2.00mg/L. In-Put style TP analysis with online thermal digestion,highly degree of automation and better accuracy of microfluidic control, is informative to thefurther miniaturization and integration of the on-line TP analyzer.