Flow-injection spectrophotometric determination of cadmium with PAN in DMF media

Field: Chemistry (Physical Sciences)

Determination of Cd 2+ by spectrophotometric method with flow injection analysis was studied using PAN as a reagent in DMF media . Cd 2+ was determined spectrophotometrically in pH 9 (The buffer produced from NH4OH,CH3COONH4) and λmax 550nm using PAN as a reagent in DMF, Beer-Lambert low was obeyed in the range (0.05-2 mg/l) with detection limit was 0.04 mg/l , e=5.4*10 4 L/mol.cm .Precision and accuracy of the method were studied (S.D=1*10 -3 ,%E=-0.18-+2.56) and interferences of dominant cations were studied . The method converted to flow injection analysis in pH 8.5 the range became (0.5-8 mg/l) in the same λmax , solvent and reagent ,detection limit become 0.2 mg/l, e=1.2*10 4 L/mol.cm . Precision and accuracy of the method was studied (S.D=0.28_-3.6,%E=-2.17-+1.72) and interferences of dominant cations were studied . 90 sample was determined in one hour in FIA. This method could be applied to the rapid and simple determination of cadmium in real sample . Introduction:The cadmium metal is very important , its very wide used (about three-fourth of cadmium is used in batteries – especially Ni-Cd batteries -) [1] .Thin film of cadmium may be applied by electro-plating ( or ,less importantly, by vaccum deposition , dipping or spraying ) to ferrous metal surfaces to retard corrosion [2] . The rather high cost may thus be worth while in special applications. Because of its great neutron-absorbing capacity, cadmium (especially the isotope 113 Cd ) is used in control rods and shielding for nuclear reactors [3] .Various methods used for determination of cadmium, including ICP-MS [4] , ion chromatography [5] , anodic stripping analysis [6] , electro thermal atomic absorption spectrometry [7] and spectrophotometry [8-12] . Many of these methods are time consuming or require complicated and expensive instruments or the determination occurs in a solvent some times the complex will be precipitated in high concentration level . In our study , the determination of cadmium was spectrophotometrically performed in DMF media . Experimental:Apparatus:-Flow injection system:Fig.1 shows a schematic diagram of FIA system used for spectrophotometric determination of Cd 2+ . a. Peristaltic pump (Watson-Marlow type 202 U, multichannel) was used to propel the buffer and reagent solutions. b. Injection valve is a 6-way loop valve with various sample loops, used to inject the sample into the buffers carrier stream. c. Detector, LKB Bio chrom Ultrospec II 4050 UVVisible sprctrophotometer with a flow cell of 10mm oath length made of quartz . r. Recorder, LKB 2210 2-channel . A Philips ion-selective meter PW 9415 used for pH measurements. Same spectrophotometer used for batch method with quartz flow cell. Fig.1:Schematic diagram of spectrophotometric determination of Cd 2+ by flow injection system. -Reagents:All chemicals used were of analytical grade. -Stock solution of Cd 2+ (1000 mg/l) was prepared by dissolving 2.1032 gm of Cd(NO3)2 in 1L of distilled water.Tha dilute solution prepared from the stock solution. -Preparation of PAN [1-(2-pyridyl azo)-2-naphthol] solution 4*10 -3 mol/l. 1 gm of PAN dissolved in DMF and the volume completed to1L with the same solvent. A-Batch method:-Recommended procedure:Reaction coil D e te c to r Recorder Waste Peristaltic pump Sample