Study And Application On The Determination Of Trace Metals By The Solid-Phase Spectrophotometry

With the development of science and technology and the continuous improvement of standards,the determination of trace metals in samples develop to ppb level currently.Instruments would be necessary on this level,but the instruments are always expensive.Solid-phase spectrophotometry introduced in this paper is a method that contains enrichment, form complex and determination.Simple, rapid,high sensitivity and less cost are the characteristics of SPS,the method is suitable for the lack of related instruments and when determinating trace metals.SPS can be used in field detection with high accuracy.This paper mainly studies on the application of resin phase spectrophotometry which is one of the SPS on the determination of trace metals.The experiment has focused on the influence of pH,buffer solution selection,reagent dosage,reacting time to set up the best experimental conditions. The method has the following characteristics:the ion was determined at the max absorption wavelength while the resin was used for control phase after being complexed with chromogenic agent firstly,then put the resin into the cuvette.The recovery is in accordance with the requirements of trace metal analysis.This paper studied on the following four systems:1.The first part is the determination of trace amounts of Cu(Ⅱ) in aluminum alloy by Cu(Ⅱ)-sodium diethyldithiocarbamate (Copper reagent) system.The apparent molar absorptivity is1.28×105L·mol-1·cm-1, the detection limit is0.037μg/mL (3σ). When the concentration of Cu2+was0.5μg/mL,the precision of the method is1.3%(n=11).The recoveries of lead ranging to determinate trace amounts of Cu(Ⅱ) in aluminum alloy by this method is between94%to104%.2.This part is the determination of Pb(Ⅱ) in steel and soil samples by Pb(Ⅱ)-Xylenol Orange disodium salt(XO) system.The apparent molar absorptivity is2.2×106L·mol-1·cm-1, the detection limit is0.0065μg/mL (3σ).When the concentration of Cu2+was0.18μg/mL,the precision of the method is2.2%(n=11).The recoveries of lead ranging to determinate trace amounts of Pb(Ⅱ) in steel and soil samples by this method is between96%to106%.The method finished with satisfactory results.3.The third part is about the determination of Cr(Ⅵ) in soil sample by Cr(VI)-diphenylcarbazide(DPCI)-OP system.The apparent molar absorptivity is1.5×106L·mol-1·cm-1, it’s sixty times higher than that in liquid phase spectrophotometry(ε=2.5×104L·mol-1·cm-1.The detection limit is0.0047μg/mL (3σ).When the concentration of Cr(Ⅵ) was O.1μg/mL,the precision of the method is1.9%(n=11).The recoveries of lead ranging to determinate trace amounts of Cr(Ⅵ) in soil samples by this method is between99%to102%4.The final part is the determination of Fe(Ⅱ) in industrial waste water and soil samples by Fe(Ⅱ)-l,10-Phenanthroline monohydrate (phen)-OP system.The apparent molar absorptivity is1.9×106L·mol-1·cm-1,it’s nearly ninety times higher than that in liquid phase spectrophotometry (ε=2.1×104L·mol-1·cm-1).The detection limit is0.0044μg/mL (3σ).When the concentration of Fe2+was0.1μg/mL,the precision of the method is2.6%(n=11).The recoveries of lead ranging to determinate trace amounts of Fe(Ⅱ) in industrial waste water by this method is between93%to103%.There was no obvious interference while setting up the experiment about effect of coexisting ions on those four kinds of systems.Masking agent can eliminate the interference of some ions.This method is rapid, simple,and spend less as well as easy to determinate at the spot. It’s an effective way to determinate metal ions in the field quickly and accurately.