IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 Removal Interferences with Spectrophotometric Study for the Determination of Chromium, Vanadium and Their Application A. H. Jassim, *B. B. Qassim, A. S. Mansoor Departme nt of Chemistry, College of Science,Unive rsity of Al-Nahrian *Departme nt of Chemistry. College of Science-Unive rsity of Baghdad Abstract The sp ecies of Cr (III), Cr (VI) in biological samples and V(IV), V(V) in foods & p lants samp les were determined by sp ectrop hotometric methods. Int egrated sp ectral st udies of comp lexes [Cr (III, VI)-DPC], [Cr (VI)-bipy ], [VO-SH], [V (V)-8-HQ] which included a st udy of the op timum conditions for the comp lexes formation by the invest igation of the chemical and p hy sical variables affecting each comp lex formation, the nature of comp lexes, the preparation of calibration curves of the complexes and treated the resulted data by modern st atist ical methods and st udy the interfering sp ecies. Interferences were removed to exp lain the reactions thermody namically by determining Ece ll, Keq. and ∆G values and includes a st udy of sep arating the interfering ions from chromium and vanadium ions by using ion exchange columns. The linear ranges of determination for Cr (III), Cr (VI) and V(IV), V(V) were 0.5-8 µgml -1 with correlation coefficients of 0.9985 to 0.9995. The detection limit for Cr(III), Cr(VI), V(IV) and V(V) were found to be 20, 15, 50 and 100 ng.ml -1 , resp ectively. Precision was ty p ically bett er than 1.5 %, based on trip licate injections. T he satisfactory recovery of 98.9 % ~ 100.81 % for Cr (VI) could be obtained from blood and urine samples and of 99.24 % ~ 101.09 % for V (IV) could be obtained from foods samples. The results agreed with those obtained by sp ectrop hotometric determination with st andard addition method and with certified values of st andard reference samples. Introduction The chemical sp ecification of trace elements in biological and environmental samples is very imp ortant, because the effects of elements, esp ecially trace heavy metals, on ecological and environmental sy st ems are generally influenced by their chemical forms. Cr (III) is p resent as several hy droxide sp ecies, such as CrOH 2+ , Cr(OH) 2 + , Cr(OH)3 and Cr(OH)4, Cr2(OH)2 4+ and Cr3(OH)4 5+ . Cr (VI) may be present in the solutions CrO4 2- , Cr2O7 2- , HCrO4 - and HCr2O7 - . Cr (VI) is reported to be toxic and carcinogenic to human even at relatively low concentration level [1]. Chromium is an essential nutrient required for normal glucose and lipid metabolism as it enhances t he effect of insulin [2]. Insulin play s a role in the metabolism of fat and p rotein. Thus chromium p lay s an imp ortant role in the body as it behaves as a cofactor by enhancing the resp onse of the insulin receptor to insulin [3,4], chromium is found in most fresh food and drinking water. Sources rich in chromium include bread, cereal, fresh vegetables, meats, sp ices, fish, brewers, y east and beer [5]. In nature, vanadium occurs in two different oxidation forms, V (V) and V (IV). Both sp ecies can exist in the environment but V (V) is the most abundance and toxic sp ecies. Ot her oxidation states such as V(II) and V(III) are not st able and will be oxidized to V(IV) and V(V) by atmosp heric oxy gen [6,7]. Vanadium is essentially required as a beneficial element that help s in carbohy drate metabolism prevention of some heart diseases [8]. Vanadium is an IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 essential micronutrient needed for cellular metabolism, and it may p lay a role in reducing cholesterol. Vanadium has been found to st imulate insulin action. It is also useful as a sup p lement for ty p e II diabetics, resulting in modest reductions of blood sugar and hepatic (liver) insulin resistance [9]. Vanadium is found in very small amounts in a wide variety of foods, including many cereals, fishes, fresh fruits and vegetables which contain this element more than 40 mg p er gram of food. Foods rich in vanadium include mushrooms; black p epp er, parsley , shellfish and dill seed [10], chromium and vanadium are introduced into the environment by effluents in several industries. It is imp ortant to control these elements since they are both toxic and carcinogenetic. A number of methods for the differential determination of chromium and vanadium by AAS [11-14], ion exchange [15-17], ICP-AES [18,19] and FIA technique [20,21] coupled to other method have been described. The sp ectrop hotometric methods [22-28] of different sp ecies of Cr and V have been successfully p erformed with high sensitivity for the determination. The main purp ose of this work was to establish a simple, sensitive and rep roducible method for the determination of Cr(III), Cr(VI), V(IV) and V(V) by the descrip tion of an integrated sp ectral st udy of comp lex [Cr (III, VI)- DPC), Cr (VI)-bipy ), (VO-SH) and (V(V)-8-HQ), resp ectively. The p rop osed method has been app lied to the determination of chromium in the biological samples and vanadium in p lants & foods with satisfactory results. Experimental Apparatus A double-beam UV–Visible sp ectrop hotometer model (UV-1650 PC) Shimadzu/ (Jap an) interfaced with comp uter via a shemadzu UV-probe data sy st em p rogram was used for the absorbance measurements and p H meter Orion exp andable ion analyzer model (EA 940) equip p ed with a glass combination electrode was used, quartz cells, (1cm), sensitive electronic balance (satorius, BL2105), cationic exchanger (IR-120 (Na + ))and anionic exchanger (IR-400 (Cl - )). Reagents Cr(VI) 100 p p m: 0.02827g of K2Cr2O7 (BDH); Cr(III) 100 p p m: 0.07692g of Cr(NO3)3.9H2O (Riedel-de-Haen); (VO +2 ) 100 p p m: 0.04966g of VOSO4.5H2O (BDH); (VO2 + ) 100 p p m: 0.017843 g of V2O5 (BDH); 1,5-Dip henylcarbazide, 2.58×10 -2 M : 0.125g/100ml acetone (Fluka A.G); 2,2'-Bipy ridine, 1mM : 0.015612g/100 ml distilled water (Fluka A.G); Thioglycolic acid HS-CH2COOH, 3mM : 5ml/50ml distilled water, 8- Hy droxy lquinoline 8-HQ, (BDH) 1mM : 0.01452g/ 100 ml chloroform (Fluka A.G); H3PO4, 1:1 (V/V): 50 ml (15.717M )/50ml distilled water; H2O2 2M : 60.7ml (16.47 M )/500 ml distilled water (solvay). H2O2 was calibrated with KM nO4; NaOH 1M : 4g/100 ml distilled water; H2SO4 1M : 27.864 ml (17.944 M )/ 500 ml distilled water; HCl 1M : 8.548 ml (11.63 M )/ 100ml distilled water; HNO3 1M : 4.593 ml (21.774 M )/ 100ml distilled water; CH3COOH 1M : 28.74ml (17.396 M )/ 500 ml distilled water; CH3COONa 1M : 8.2 g/100 ml distilled water. Preparation of 100ml Inte rfering Ion (100 µgml -1 ) Co(II):- 0.04937g of Co(NO3)2.6H2O, Cd(II):- 0.02584g of Cd(NO3)2.3H2O, Cu(II):- 0.03842g of Cu(NO3)2.3H2O, Ni(II):- 0.0495g of Ni(NO3)2.6H2O, M g(II):- 0.1013g of M gSO4.7H2O, M n(II):- 0.0457g of M n(NO3)2.4H2O, S2O3 = :- 0.02214g of Na2S2O3.5H2O, Br - :- 0.01084g of LiBr, I - :- 0.01142g of NH4I, C2O4 = :- 0.01523g of Na2C2O4. Treatme nt of samples *Urine samples The urine samples were treated with 2m l of p erchloric acid 60% (v/v) for the purp ose of the protein sedimentation [29]. IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 *Blood sample s [28, 29] The blood samples were treated with 5ml of H2O2 and 5 ml conc. HNO3, the solution was heated until the excess acid was exp elled. Aft er dry ing, added 5 ml (1:1) HCl , 5 ml HNO3 and 20 ml D.W were added after that was filtered the solution. *Plants and foods samples [28, 29] The p lants and foods samples were dissolved (mushroom, cereal and st rawberry) in 50ml of a mixture (HCl: HNO3) (1:1) (v/v) with heating to comp lete dissolve then the solution was filtered and diluted to 250 ml in volumetric flask with dist illed water. Preparation of Metal Complexes Chromium–1,5-Di phe nyl carbazide (DPC) complex Cr(IV) reacts with 1,5-diphenylcarbazide in acidic medium to form a red-voilet color comp lex which exhibits a measure band absorbance at 542 nm. A concentration range of (0.5- 8) p p m of Cr(VI) has been p repared by diluting a st andard solution of 25 p p m concentration which adjust s at (p H=8-8.5) in basic medium (NaOH), in volumetric flask 50 ml, 1ml of diphenylcarbazide was added with st irring to the chromium solutions followed by 2.5 ml H3PO4 (1:1) and then diluted to the mark by distilled water. The [Cr(VI)-DPC] comp lex could be formed by st arting with chromium (III) ions and oxidized to Cr(VI) after adding an excess sodium hydroxide (NaOH) followed by a 5 ml of 6% hydrogen peroxide (H2O2) [29]. A sample from the flask transferred to a sp ectrop hotometer cell and the absorbance was measured at 542 nm. Chromium-2,2 ' -Bipyridine (bipy) Comple x [29] Cr(IV) reacts with 2,2`-bipy ridine in acidic medium to form a light blue color comp lex which exhibits a measure band absorbance at 308nm. A concentration range (0.5-8) p p m of Cr(VI) was p repared by dilution in 25 ml volumetric flask. An aliquot (5 ml) of this solution was transferred to sep arate funnel and acidified with 1ml of 1M sulfuric acid. Sufficient distilled water was added to bring the total volume to 20ml and then about 20 ml of ethy l acetate was added. The funnel and its contents were cooled at 10C for 1/2 hour. Aft er cooling, 1ml of a 3 % solution of hy drogen p eroxide was added and also cooled at 10C and immediately extracted by vigorously shaking the sep aration funnel for 30 second. Aft er the lay ers being sep arated, the aqueous lay er was discarded. The ethy l acetate lay er was added to 10 ml of 0.6 mM aqueous solution of 2, 2'- bipy ridine which was also cooled at 10C and immediately extracted by a vigorous shaking for 30 seconds. Aft er the lay ers were sep arated, the aqueous lay er was discarded and transferred the ethy l acetate layer to a 25 ml volumetric flask, and diluted to t he mark with an additional ethy l acetate and measured the absorbance of sample at 308 nm buffer solution (p H=5.64). Vanadium–Thi oglycoli c acid (S H) complex [30] V(IV) reacts with thioglycolic acid in buffer solution from sodium acetate (p H=5.0- 5.5) to form a very light blue color comp lex which exhibits a measure band absorbance at 225 nm. A concentration range of (0.5-8) p p m of V (IV) was p repared in 50 ml of volumetric flasks, 5 ml of 30 mM thioglycolic acid and 1ml of 0.15 M sodium acetate were added and the solution was adjust ed at (p H=5.0-5.5), the solution was diluted to the mark by distilled water and after that was shacked, and measured the absorbance at 225 nm. Vanadium-8-Hydroxyqui nol ine (8-HQ) complex [29] V(V) reacts with 8-hy droxy quinoline in acidic medium (p H=3.5-4.5) to form a brown color comp lex which exhibits a measure band absorbance at 550 nm. A concentration range of (0.5-8) p p m of V(V) was p repared in 50 ml volumetric flasks, 1ml of 1M H2SO4 was added; IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 the solution was adjust ed at (p H=3.5-4.5) and the solution was t ransferred to 100 ml sep aratory funnel. Then 5 ml of 1mM 8-HQ was added and immediately extracted by a vigorous shaking for 30 seconds. Aft er the lay er was sep arated, the aqueous lay er was discarded and transferred to 50 ml of volumetric flask and then diluted to t he mark by distilled water, and measured the absorbance at 550 nm. Re sults and Discussion S pectrophotome tric S tudy of Chromium and Vanadium Comple xes of Various Valences This st udy includes the scanning of the sp ectrum of the reagents in the ultraviolet- visible region, by taking certain volumes of reagents in a measuring cell versus a blank. The comp arison of t he absorp tion sp ectra of [Cr(VI)-DPC], [Cr(VI)-bipy ] and [VO-SH], [V(V)-8- HQ] comp lexes with reagents and metals as shown in figures (1), (2) resp ectively and figure (3) shows a comp arison of the absorp tion sp ectra of the (Cr-DPC) comp lex formed st arting with p otassium dichromate Cr2O7 = and the absorp tion sp ectra of the complex formed st arting with Cr(III). It has been found that t he absorp tion intensity of the comp lex was less t han that obtained with Cr2O7 = ion. Studying the Optimum Conditions for Complexes Formation  Effect of the reage nts concentration A set of variable concentrations of reagents has been p repared to determine the op timum concentration to the highest absorp tion intensity . Fig. (4) Shows that the op timum concentration of DPC reagent in [Cr (III, VI)-DPC] comp lex was (25.8 mM ), and the op timum concentration of (bipy ) reagent in [Cr (VI)-bipy ] comp lex was (0.6mM ), Fig. (5) Shows that the op timum concentration of (SH) reagent in [VO-SH] comp lex was (3mM ) and the op timum concentration of (8-HQ) reagent in [V (V)-8-HQ] comp lex was (1mM ). The op timum concentration of reagents gave a regular increase to the signal which is app rop riate for analytical p urp oses.  Effect of pH This effect has been st udied by using a fixed concentration of both metal ions and reagent solutions, where a series of solutions have been p repared; in the first series, the comp lexes formation were st udied at different ty p es of solutions [1M H2SO4, 1M H3PO4, 1M CH3COOH, (0.2M CH3COOH + 0.2M CH3COONa), 1M CH3COONa, 1M NaOH], where 1 ml of each solution was taken. The second series of solutions includes the reagent only, the absorbance was measured first , and then the p H was measured for the standard solutions. The results show that t he maximum absorbance of the [Cr (III, VI)-DPC] comp lex was at (p H=8- 8.5) in the p resence of NaOH, fig. (6) shows that the maximum absorbance of the [Cr (VI)- bipy ] comp lex was at (p H=4-4.5) in the p resence of H2SO4 and fig. (7) shows that the maximum absorbance of the [VO-SH] comp lex was at (p H=5-5.5) in the p resence of CH3COONa and the maximum absorbance of the [V (V)-8-HQ] comp lex was at (p H=3.5-4.5) in the p resence of H2SO4.  Effect of acids or base concentration A set of solutions of variable concentrations has been p repared to determine the op timum concentration which shows the highest absorp tion intensity . Fig (8) shows that the op timum absorbance of [Cr (III, VI)-DPC] comp lex at the constant DPC reagent and ion concentration when 1ml of 1M NaOH solution was added and the op timum absorbance of [Cr (VI)-bipy ] comp lex at the constant (bipy ) reagent and ion concentration when 1ml of 1M H2SO4 was added solution, fig (9) shows t hat t he optimum IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 absorbance of [VO-SH] comp lex at the constant (SH) reagent and ion concentration when 1ml of (0.15M ) CH3COONa solution was added and the op timum absorbance of [V (V)-8-HQ] comp lex at t he const ant (8-HQ) reagent and ion concentration when 1ml of (0.1M ) H2SO4 solution was added. Studying the Effect of the Physical Variable on Complexes Formation  Time Effect The absorbance was measured at different p eriods of time in the absence of light. It can be noticed from figure (10) that the comp lexes were fixed for long p eriods of time up to several hours through the const ant absorbance of the complexes.  Light Effect The absorbance of [Cr(VI)-DPC] comp lex was measured at different p eriods of time in the p resence of daylight and radiation light. The results show the absence of any influence of daylight and radiation light on the comp lexes st ability for a p eriod of time ranging from several minutes t o several hours. As shown in figure (11).  Temperature Effect The effect of temp erature on the [Cr(VI, III)-DPC], [Cr(VI)-bipy ], [VO-SH] and [V(V)-8-HQ] comp lexes absorp tion as shown in figure (12). The results show that the analysis within room temp erature (25-35) ° C was app rop riate where the [Cr-DPC], [VO-SH] and [V(V) - 8-HQ] comp lexes was stable and the time analysis at (10-15) ° C were app rop riate where the [Cr (VI)-bipy ] comp lex was stable. Nature of Complexes Formation Ap p lying the op timum conditions, which were obtained p reviously , the metals to reagents ratio in the [Cr (III, VI)-DPC], [Cr (VI)-bipy ], [VO-SH] and [V (V)-8-HQ] comp lexes were obtained by following continuous variation method, where a series of solutions was p repared in which the formal concentration of the metal ions and reagents were held constant (0.5M ) while varying volume ratios. The final volume was 10 ml for each solution. Fig. (13) shows t he p lot of t he absorbance versus mole fraction of the reactants, (A) shows the Cr (III, VI) / DPC ration app eared to be 1:2 at p H=8-8.5 and λm ax=542 nm, (B) shows t he Cr (VI) / bip y ration app eared to be 1:2 at p H=4-4.5 and λm ax=308 nm, (C) shows the V (IV) / SH ration ap p eared to be 3:2 at p H=5-5.5 and λm ax=225 nm and (D) shows the V (V) / 8-HQ ration ap p eared to be 1:2 at p H=3.5-4.5 and λm ax=550 nm. And fig. (14) shows t he suggested structure of the complexes resp ectively. Calibration Curves A calibration curve was p repared from a series of standard solutions in the range (2-8) p p m, using the op timum conditions for the comp lexes formations. The absorbance measurements were made at 542 nm for the [Cr (III, VI) – DPC] comp lexe, 308 nm for the [Cr (VI) – bipy ] comp lex, 225 nm for [V (IV)- SH] comp lex and 550 nm for the [V (V)-8- HQ] comp lex. Linear curves were obtained as shown in figure (15) A, B. Table (1) shows that treatment data resulted from modern statist ical treatment [31-32]. Studying The Effect of Interfering Ions This st udy was conducted to interpret the effect of interferences of some positive and negative ions and to find the p ercentage effect of these ions on the absorp tion intensity , and also t o demonst rate the effect of changing the metal's behavior and how some reactions were p referred thermody namically (increasing the absorp tion intensity ) and others were non- p referred (reducing the absorp tion intensity ). The interpretation was exp lained on the basis of some thermodynamic quantities (ΔG, E ◦ ce ll, Keq). According to the mechanism of the reaction there are some p referred reactions according to the thermody namic view p oint, since E ◦ ce ll of the net reaction is p ositive, as will be exp lained later. The reaction is exothermic, represented by the negative value of ΔG, which means t hat t he reaction is sp ontaneous. T he selected ions are: IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 Positive ions: Cd(II), Cu(II), Co(II), M g(II), Zn(II), Ni(II), V(IV), V(V) and M n(II). Ne gative ions: I - , Br - , Cl - , IO3 - , NO3 - , S2O3 = , Cr2O7 = and C2O4 = . Table (2) shows the effect of V 5+ , V 4+ , Co 2+ Cd 2+ , Cu 2+ , M g 2+ ions to increase the absorbance intensity of Cr (VI), which was exp lained by the following dy namic equations:- C r2O7 = +14H + +6e - 6×[V O2 + +2H + +e - 7H2O+2Cr 3+ ----( 1) E=1.33V VO 2+ +H2O] -----( 2) E= +1 .00V Cr2O 7 =+14H++6e- 6VO 2 + 12H+ 6e- 7H2O+2Cr 3+ - ---(1) E=1.33V 6VO2+ 6H2O ----( 2) E= 1.00V ± ± ±±±± Cr2O7 = +6VO 2+ +2H + 2C r 3+ +6VO 2 + +H2O ----(3) Ec ell =+0.3 3V ° In equation (3), we notice that this reaction was p referred thermody namically because the p ositive value of E ° ce ll and the negative value of ΔG equal to (-45.72Kcal). The reaction was exothermic which means it is sp ontaneous and the equilibrium constant (Keq.) was calculated via app lying the following equation [33]:- Log K= nFEcell 2.303 RT Keq =3.028×10 33 The interference of iodide (I - ) with chromium ions was increased the absorbance intensity and this was exp lained by the following dy namic equations:- Cr 2 O 7 = +14H + +6e- 3×[ I2 + 2e - 7H 2 O +2Cr3+---(1) E=1.33V 2I - ] ---(2) E= 0.535V Cr 2 O 7 =+6I -+14H + 2Cr3 ++ 3I 2 +7H 2 O ---(3) E cell = +0.795V° ± Cr 2O7 = +14H+ +6e- 3I2 6e 7H 2 O +2Cr 3---(1) E=1.33V 6I - ---(2) E= 0.535V± ± ± In equation (3), the reaction was p referred thermody namically because the value of E ° ce ll is p ositive and the value of Keq. is (K=4.56×10 80 ), which means that t he dichromate ions were able to oxidize (I - ) and liberates iodine (I2). This reaction was sp ontaneous because of the negative value of the ΔG ° (-110.13Kcal), (G=-nFEce ll). The other interferences could be exp lained in the same manner, since the values of p otential cell index for Cu 2+ , Cd 2+ , Co 2+ , and M n 2+ ions are: - 0.99, 1.73, 0.512, and -0.17 resp ectively. In table (3) the manganese ions (M n 2+ ) decreased the absorbance intensity of V (IV) ion; and as shown in the following equations:- IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 5× [VO 2+ + 2H + +e - MnO4 - + 8H + + 5e - V 3 + + H2 O] -----(1) E= 0.34V Mn2 ++ 4H2O ----(2) E=+1.5V Mn 2+ +5V O 2+ +2H + MnO4 - +5V 3+ +H2O ----( 3) Ecell= -1.16V ° 5VO 2 + + 10H + + 5e - MnO4 - 8H + 5e - 5V 3 + + 5H2O -----(1) E= 0.34V Mn 2+ 4H2O -----(2) E= 1. 5V ± ± ± ± ±± The permanganate ion (M nO4 - ), M n (VII) behaved as a st rong oxidizing agent; (M nO4 - ) reduced the V (IV) to V (III) and gave a low resp onse for the absorp tion intensity . This reaction was not-p referred thermody namically because the p ositive value for ΔG ° (+133.9 Kcal) and negative value of E ° ce ll (-1.16 V). The (VO 2+ ) may also be contributed to convert the M n 2+ to a lower oxidation st ate not only on M n (VII). This resulted for the consumption of (VO 2+ ). The interferences of Cd 2+ ions with V (IV) increased the p ercentage effect; the ΔG (- 34.17 Kcal) and E ° ce ll (+0.74 V); this means that the reaction was exothermic and sp ontaneous; thus, it was p referred thermodynamically according to the following equations: - 2 × [ V O 2 + + 2 H + + e - C d 2 + + 2 e - V 3 + + H 2 O ] - - -- -( 1 ) E = 0 .3 4 V C d - -- -- -- ( 2) E = - 0 .4 V C d + 2 V O 2 + + 4 H + C d 2 + + 2 V 3 + + 2H 2 O - -- -- (3 ) E c e ll= + 0 .7 4V ° 2 V O 2 + + 4 H + + 2 e - C d 2 + 2 e - 2 V 3 + + 2 H 2 O -- -- -( 1 ) E = 0 .3 4 V C d - -- -- - (2 ) E = 0 .4 V± ± ± ± The interference of bromide (Br - ) ions with vanadium (IV) ions decreased the absorbance intensity of V (IV) ions, this was exp lained by the following dy namic equations:- 2× [V O 2++ 2 H+ +e - Br2 + 2e - V 3 ++ H2 O ] --- (1 ) E= 0.3 4V 2Br - ---- (2 ) E= + 1.0 7V ° 2V O 2++ 4 H+ +2 e- Br2 2 e- V3 + + H2O -- --( 1) E = 0.34 V 2Br - - --- (2) E= 1.07 V ± ±±± 2Br-+ 2V O 2++ 4 H+ Br2+ 2 V 3 + + 2H2 O ---( 3) E c ell = - 0.73 V What is noticed in equation (3), the reaction was not-p referred thermody namically because of the negative value of E ° ce ll, which means that the vanadium ions were able to oxidized Br - and liberate Br2. The reaction was non-sp ontaneous because of the positive value of the ΔG ° (+33.71 Kcal). The interference of magnesium (M g 2+ ) ions with vanady l ions increased the p ercentage effect, t his was exp lained by the following dy namic equations:- 2 × [V O 2+ + 2 H + + e - M g 2+ + 2 e - V 3 + + H2 O ] -- -- - (1 ) E = 0 .3 4 V M g -- -- - -- (2 ) E = -2 . 3 4 V M g +2 V O 2+ +4 H+ M g 2+ +2 V 3+ +2 H 2O - -- (3 ) E ce ll = +2 . 6 8 V ° 2 V O 2 + + 4 H + + 2 e - M g 2+ 2 e - 2 V 3+ +2 H 2 O -- -- -- -( 1 ) E = 0 . 3 4 V M g -- -- -- (2 ) E = 2 . 3 4 V±± ± ± What is noticed in equation (3), the reaction was p referred thermodynamically because of the positive value of E ° ce ll. The reaction is sp ontaneous because of the negative value of the ΔG ° (-123.76 Kcal), but in the low concentration of interferences, the ions gave a high IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 p ositive value; through the observation of the reaction equation of magnesium, the ions may be remained in solution and then they increased the percentage effect. From the p revious st udies, we knew that the interfering ions were able to increase or decrease the absorp tion intensity of the metal ions. So these effects should be removed to obtain a result with a high accuracy for the determination of chromium and vanadium ions. The best method used to remove the interferences ions influence was ion exchange method which is illust rated in tables (4) and (5). The cationic exchanger was used to remove some of the p ositive ions effect and to measure the p ercentage of interferences effect before and after the sep aration of Cr (VI) ions which are illustrated in table (2) but the negative ions were difficult to remove from the dichromate [Cr2O7 = ] which is noticed, thus, it should be converted from dichromate ions into chromate ions in basic media, then reduce chromate ion Cr (VI) to Cr (III) by ethanol with heating [29] and then the p assing through the negative ion exchange column was allowed to take the interferences ions under st udy and to leave Cr (III) ions measured by sp ectrop hotometry . Vanadium ions was an excep tional behavior, vanady l ion carries a p ositive charge in the acidic media at (p H=1-6) of formula (VO 2+ ) and carries a negative charge in a st rong alkaline media of formula VO (OH)3 - and (VO2) (OH)5 - at (p H=8-12), thus vanadium has an Amphote ric behavior [33]. According to the above when removing the p ositive ions interferences from V (IV), the medium should be alkaline in order to ensure the existence of vanadium in the negative form [(VO (OH)3 - ) and ((VO2) (OH)5 - )], but its difficult to remove these ions because vanadium p recipitate in the high alkaline media. To see Amphote ric behavior for vanadium [33], and to remove the negative ion interferences for V (IV), acidic media 1M H2SO4 was used at (p H=1-6) to ensure the vanadium ions as p ositive formula of (VO 2+ ). Then the negative ion exchange column was p assed through to replace the negative ions leaving vanadium ions measured by sp ectrop hotometry which are illust rated in table (3). Applications The prop osed method was app lied to the quantitative determination of chromium and vanadium in biological samples (blood and urine for chromium, and p lants and foods for vanadium). Chromium and vanadium ions were determined in samples after treatment (2-4). The absorp tion was measured for the samples after treatment and after adding (0, Z, 2Z, 3Z) mg.ml -1 of metal ions to (5ml) of samples in (25ml) volumetric flask. Fig. (16) and fig. (17) showed the relationship between chromium ions added to the samples (urine, blood) and fig. (18) showed the relationship between vanadium ions added to the samples (mushroom, cereal and st rawberry) against the absorbance, the intercep t p oint (C) represented the amount of metal ions. Recovery for total amount of metal ions and recovery for the amount of metal ions in samp le only (from calibration curve) were calculated and the quantity of metal ions found in samples using sp ectrop hotometric method (3-1) as shown in tables (6), (7) and (8) resp ectively. Conclusions In the light the present study the following conclusions were drawn:- - The feasibility of the UV-Vis sp ectroscop ic st udy to determine the trace elements in biolo gical samp les. - The possibility of using thermody namic calcu lations (Ece ll, Keq. and ΔG) to determine the way in which the interfering ions can affect t he determination of Cr (VI) and V (I V). - The method was app lied successfully for the determination of trace amount of Cr (III), Cr (VI), V ( V) and V (I V) in bio logical samp les and foods with no effects or it had a little IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 interference by ions in samples with using ion-exchange columns to overcome the interferin g ions. - The p ossibility of extending the ideas and results obtained from this work to st udy the medical, p harmaceutical and biolo gical samples due to their simplicity , sp eed, high sensitivity (low detection limit) and economy, in addition to the high accuracy since the results showed that the comp lex formation sy stem was the most suitable one to determine the chromium and v anadium ions in biology and livin g without the need for pretreatment. Re ferences 1. Shanker,A.K.; Cervants,C. ; Loza-Tavera ,H. and Arudainay agam,S. (2005) Environ. Int., 31:739-753. 2. Kot as ,J. and Stasicka, Z. (2000); Environ. Pollut, 107: 263 3. Repinc ,U.K. and Benedik, L. (2004)Acta Chim. Solv., 51: 59-65. 4.V.Aroncibia, M .Volderrama, K.Silva, and T.Tapia, (2003); Journal of Chromatography B, 785:303-309. 5. Threep rom,J.; Purachaka,S. and Pot ipan,L. (2005); Journal of Chromatography A, 1073: 291-295. 6. Geaffrey , W. and Albert,C.F. (1966), “Advanced Inorganic Chemistry ”, 5 th ed. New York, 821. 7. Nukatsuka,I. ; Shimizu ,Y. and Ohz eki,K. (2002); Anal. Sci., 18:1009. 8. Awofolu,O.R. (2004) AJST, 5: 15-21. 9.Villani, P. ; Cordelli,E.; Leop ardi,P.; Siniscalchi, E.; Veschetti, E. ; M .Fresegna A. and Crebelli,R. (2007); Toxicology Letters, 170:11-18. 10. Kiran Kumar ,T.N. and Revanasiddap p a ,H.D. (2005)J. of the Iranian Chem. Soc., 2(2): 161-167. 11. Soy lak,M . ; Saracoglu,S. ; Divrikli ,U. and Elci,L. (2005); Talanta, 66:1098-1102 12. Sahay am,A.C. ; Venkateswarlu,G. and Chaurasia,S.C. (2005); Analytica Chimica Acta, 537:267-270. 13. Fernandesa, K.G.; Nogueira,A.A.; Gomes Netoc, J.A. and Nóbregaa, J.A. (2004); J. Braz. Chem. Soc., 15: 676-681. 14. Amorim,F. ; Lima,D.; Amaro,J.A. ; Valea,M . and Ferreira, S. (2007); J. Braz.Chem. Soc., 18:1566-1570. 15. Gavazova ,K.; Lekovaa, V. and Patronovb G. (2006)Acta. Chim. Solv., 53: 506-511. 16. Hu, M . and Coetzee,P. (2007); Anal. Chim. Acta., 3: 291-29. 17. Hu ,M . and Coetzee P. (2002); Anal. Chim. Acta. , 28:37-44. 18. Sumida,T. ; Sabarudin,A. ; Oshima ,M . and M otomizu,S. (2006) J.Soci.Analy . Chem, 22:161-164. 19. Agrawal ,Y.K. and Thaker; D.N. Chem. Soc. Confere. & Exhib., (2007), Jan. 23-24. 20. Hamid, S.; M ohammad,A. ; Dadfarnia ,S. and Taei, M . (2007); Turk J Chem, 31:191-199. 21. Nakano,S. ; Tanaka ,E. and M izut ani ,Y. (2003); Talanta, 61:203-/210 22. Narayana, B. and Cherian,T. (2005); J.Braz.Chem.Soc, 16, 197-201. 23. El-Shahawi, M .S.; Hassan,S.S.M . ; Zy ada M .A. and El-Sonbati, M .A. (2005); Analytica Chimica Acta, 534: 319–326. 24. Ghaedi,M .; Asadp our ,E. and Vafaie,A. (2006) Sp ectrochimica Acta Part B, 63: 182-188. 25. Suvarap u,L.N. ; Somala,A.R. ; Bobbala, P.; Inseong ,H. and Ammireddy V.R. (2009) E. Journal of Chem., 6(S1):459-465. 26. Kumar,K.S. ; Kang,S.H. ; Suvardhan ,K. and Kiran, K. (2007) Environmental Toxicology and Pharmacology , 24:37-44. IBN AL- HAIT HAM J. FOR P URE & AP P L. SCI VOL. 23 (3 ) 2010 27. Kumar,K.S. ; Suvardhan,K.; Krishnaiah,L. ; Janardhanam, K.; Jay araj B. and Chiranjeevi, P. (2007) Talanta, 71: 588-595. IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 28. M arczenko Z. “Sp ectrop hotometric determination of elements”, (1976), Warsaw; 213- 223. 29. Vogel, (1979), “textbook of M acro and Semimicro Qualitative Inorganic Analysis”, 5th ed. Longman, 256. 30. Jassim ,A.H. and Kasim, B.B. (2007); J.of Al-Nahrain University science, 10:14-22. 31. Sharma, S.D. (1989), “Op erations research and st atist ical analysis”, 1 st ed, p ublished by kedar.N.N & Co-meerut, U.P.India 88-102. 32. J.M urdoeh and J.A.Barnes, (1974), “ Statist ical tables”, 2 nd edi, M acmillan. 33. B.L.Valas and P.J.Casta, (1978), “Comprehensive coordination chemist ry ”, 541:2242, c.728 (ed.W.S.Geofery). 34. By rne ,A.R. and Kost a, L. (1978); Soc.tot al Environ., 10:17-30. 35. M y ron,D.R.; Givand, S.H. and P.H.Nielsen, (1977); J.agric food chem., 25:297-299. 36. Sǒremark,R. (1967); J.Nutr, 29:1873-190. Table (1): Outline for the results of the linear regression equati on of the complexes complexes Sl op (b) b Ŧ S * bt Inte rsection (a) a Ŧ S * at R R 2 % C r (VI) – DPC 0.32 Ŧ 0.0073 0.0275 Ŧ 0.0039 0.9985 99.7 C r (III) – DPC 0.3098 Ŧ 0.018 0.0448 Ŧ 0.0095 0.9989 99.8 C r (VI) – bi py 0.284 Ŧ 0.0089 0.013 Ŧ 0.049 0.9995 99.9 V (IV) – S H 0.327 Ŧ 0.0185 0.0257 Ŧ 0.0100 0.9989 99.8 V (V) – 8-HQ 0.2451 Ŧ 0.013 0.0885 Ŧ 0.072 0.9989 99.8 S * b: - Standard deviation of the slop Sa: - Standard deviation of the intersection, t= table value Table (2): The percentage of interferences effect of some posi tive and negative ions on the absorption i ntensity of dichromate ion [Cr2O7 = ] under the same conditions for all measurements Positive ions ppm Effect % Co 2+ Cu 2+ M g 2+ Ni 2+ Cd 2+ M n 2+ Zn 2+ V 4+ V 5+ 4 +8.26 +12.7 +8.85 -29.2 +15.7 -53.3 -13.22 +7.965 +12.41 16 +14.73 +21.81 +14.4 -35.39 +25.35 -21.3 -28.97 +42.63 +18.29 Ne gative ions ppm Effect % Cl - I - Br - C2O4 = IO3 - S2O3 = NO3 - 4 +6.37 +19.44 +5.04 -10.47 -62.54 -38.7 -50.4 16 +15.46 +25.55 +10.21 -15.52 -66.47 -41.2 -85.3 IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 Table (3): The percentage of interferences effect of some posi tive and ne gative ions on the absorption inte nsi ty of vanadyl ion [VO 2+ ] under the same conditions for all measurements Positive ions ppm Effect % Co 2+ Cu 2+ M g 2+ Ni 2+ Cd 2+ M n 2+ Zn 2+ 4 +7.92 + 9.57 +5.29 +1.52 +17.3 -15.62 -16.53 16 +11.54 +19.65 +23.14 +8.3 +15.56 -23.32 -27.273 Ne gative ions ppm Effect % Cl - I - Br - Cr2O7 = C2O4 = IO3 - S2O3 = NO3 - 4 -11.5 +12.1 -12.31 -71.9 -22.3 -41.98 +44.8 +19.54 16 -43.7 +6.4 -25.62 -112 -2.48 -19.5 +47.19 +21.33 Table (4): The percentage of interference effect before and after separation of Cr (VI) ions Positive and negative ions interferences Concentration of ions interferences with 4 ppm of metals ions Percentage of interferences effect Before se paration After se paration Cu 2+ 4pp m +12.7 +3.45 Mg 2+ 4pp m + 8.85 +2.26 Ni 2+ 4pp m - 29.2 -5.84 I - 4pp m +19.44 +9.54 S 2O3 = 4pp m - 38.7 - 6.61 NO 3 - 4pp m -50.4 -17.8 Table (5): The percentage of interferences effect before and after se paration for V (IV) ions Ne gative ions interferences Concentration of ions interferences with 4 ppm of metals ions Percentage of interferences effect Before se paration After se paration I - 4pp m +12.1 +5.81 S 2O3 = 4pp m +44.8 +14.5 NO 3 - 4pp m +19.54 + 8.33 IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 Table (6): S pectrophotome tric determination of Cr (VI) ion in urine samples The presenc e of Cr in differen t urine sample s The quantity of Cr found in urine sample onl y (practic al) mg.ml -1 v The amount of standard chromium added to the urine sample (the oretic al) mg.ml -1 y The quantity of Cr found (practical) [in urine sample + quantity of Cr added (the oretica l)] x 1 The quantity of total Cr (urine sample + the amount of Cr added) (the oretic al) x 2 Recover y for the total amount of chromiu m The quanti ty of Cr found in urine sample mg.ml 1 ( x1 -y ) Recove ry for the Cr found in urine sample (1) exhibiti on 0.874 Z: 1.748 2Z: 3.496 3Z: 5.244 Z: 2.621 2Z: 4.367 3Z: 6.111 2.622 4.37 6.118 99.96 100.93 99.885 0.873 0.871 0.867 100.11 100.34 100.81 (2) non- exhibiti on 0.685 Z: 1.37 2Z: 2.74 3Z: 4.11 Z: 2.052 2Z: 3.418 3Z: 4.792 2.055 3.425 4.795 99.85 99.796 99.94 0.682 0.682 0.682 100.44 101.03 100.44 Table (7): S pectrophotome tric determination of Cr (VI) ion in blood samples The presenc e of Cr in differen t blood sample s The quantity of Cr found in blood sample onl y (practic al) mg.ml -1 v The amount of standard chromium added to the blood sample (the oretic al) mg.ml -1 y The quantity of Cr found (practical) [in blood sample + quantity of Cr added (the oretica l)] x 1 The quantity of total Cr (blood sample + the amount of Cr added) (the oretic al) x 2 Recover y for the total amount of chromiu m The quanti ty of Cr found in blood sample mg.ml 1 - ( x1 -y ) Recove ry for the Cr found in blood sample (1) exhibiti on 0.902 Z: 1.804 2Z: 3.608 3Z: 5.412 Z: 2.707 2Z: 4.520 3Z: 6.313 2.708 4.510 6.314 99.96 100.22 99.98 0.903 0.912 0.901 99.98 98.90 100.11 (2) non- exhibiti on 0.572 Z: 1.144 2Z: 2.288 3Z: 3.432 Z: 1.715 2Z: 2.863 3Z: 4.003 1.716 2.860 4.004 99.94 100.10 99.98 0.571 0.575 0.571 100.18 99.48 100.18 IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 Table (8): S pectrophotome tric determination of V (IV) ion i n foods samples The presenc e of V in foods sample s Recod ed value µg.kg - The quantit y of V found in food sample s only (practic al) mg.ml -1 v The amount of standard vanadiu m added to the food sample s (the oreti cal) mg.ml -1 y The quantity of V found (practical ) [in food sample s + quantity of V added (the oretic al)] x 1 The quantity of total V (food sample s + the amount of V added) (the oreti cal) x 2 Recove ry for the total amoun t of vanadi um The quant ity of V found in food sampl es mg.ml 1 ( x1 -y ) Recov ery for the V found in food sample s (1) mushro om sample s a*: 50- 2000 (dry ) 1.312 Z: 2.624 2Z: 5.248 3Z: 7.872 Z: 3.935 2Z: 6.570 3Z: 9.185 3.936 6.560 9.184 99.975 100.15 100.01 1.311 1.322 1.313 100.07 6 99.24 99.924 (2) cereal sample s b*: 31.41 (dry ) 0.924 Z: 1.848 2Z: 3.696 3Z: 5.544 Z: 2.773 2Z: 4.610 3Z: 6.467 2.772 4.620 6.468 100.04 99.78 99.98 0.925 0.914 0.923 99.89 101.09 100.11 (3) strawbe rry sample s c*: 93 (dry ) 0.761 Z: 1.522 2Z: 3.044 3Z: 4.566 Z: 2.282 2Z: 3.806 3Z: 5.325 2.283 3.805 5.327 99.96 99.95 99.96 0.760 0.762 0.759 100.13 99.87 100.26 a*=St udy 1 (34 ) , b*=St udy 2 (35) , c*= St udy 3 (36) IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 Fig. (1) A:Comparison of the absorption spectra of (a) reagent at (DPC=25.8 mM) (b) metal ion at (Cr (VI) =6ppm) and (c) complex at (Cr (VI) =6pp m, pH=8-8.5, λma x = 542nm, DPC=25.8mM). Fig. (1) B :Comparison of the absorption spectra of (a) metal ion at (Cr (VI) =8pp m) (b) reagent at (bip y=0. 6mM) and (c) complex at (Cr (VI) =8ppm, pH=4-4.5, λma x=308nm, bipy=0.6mM). Fig. (2) A:Comparison of the absorption spectra of (a) metal ion at (V (IV) = 8pp m) (b) complex at (V (IV) =8ppm, pH=5-5.5, λma x=225nm, SH=3mM) an d (c) reagent at (SH=3mM). Fig. (2) B:Comparison of the absorption spectra of (a) metal ion at (V (V) =8p pm) (b) reagent at (8-HQ =1mM) an d (c) complex at (V (V) =8ppm, pH=3. 5-4.5, λma x=550nm, 8-HQ =1mM). Fig. (3): Comparison of the absorption spectra of complex (a) starting with Cr(VI) at (Cr(VI)=8pp m, pH=8-8.5, λma x=542nm, DPC=25. 8mM ) (b)starting with Cr(III) at (Cr(III)=8pp m, pH=8-8.5, λma x=542nm, DPC=25. 8mM ) IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 0 0.5 1 1.5 2 2.5 0 10 20 30 40 50 60 [Cr(IV)]mM a b s o r b a n c e i n te n s e ty Fig. (4) A : Ef fect of reagent concentration on the absorbance Intensity of the complex [Cr (VI)-DPC] at (Cr (VI) =6ppm, pH=8-8.5, λma x =542nm, DPC=25.8mM) 0 0.5 1 1.5 2 0 0.2 0.4 0.6 0.8 1 [bipy] mM a b s o r b a n c e i n te n s it y Fig. (4) B: Ef fect of reagent concentration on the absorbance Intensity of the complex [Cr (VI)-bipy] at (Cr (VI) =8ppm, pH=4-4.5, λma x=308nm, bipy=0.6mM). Fig. (5): A-Ef fect of reagent concentration on the absorbance intensity of the complex [VO-SH] at (V (IV) =8ppm, p H=5-5.5, λma x=225nm, SH=3mM) Fig. (5): B-Ef fect of reagent concentration on the absorbance intensity of the complex [V(V)-8-HQ ] at (V(V)=8pp m,pH=3.5-4.5,λma x=550nm, 8-HQ =1mM ). Fig. (6): Ef fect of p H solu tion on the absorbance intensity of the complex [Cr (VI)-bipy] (a) existence both Cr (VI) ion an d reagent solution with H 2SO 4 at (λma x =308 nm) (b) existence reagent only at (λma x =350nm). IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 Fig. (7): A-Ef fect of pH solu tion on the absorbance intensity of the complex [VO-SH] (a) existence both V (IV) ion and reagent solu tion with CH3COONa at λma x=225 nm (b) ex istence reagent only λma x=246 nm. Fig. (7): B-Ef fect of pH solu tion on the absorbance intensity of the complex [V (V)–8-HQ ] (a) existence both V (V) ion and reagent solution with H2SO 4 which prepare λma x=550nm (b) ex istence reagent only λma x=300 nm. Fig. (8): A-Ef fect of NaOH concentration on the absorbance intensity of the complex [Cr (VI)-DPC] at (Cr (VI) =6ppm, pH=8-8.5, λma x =542nm, DPC=25. 8mM) Fig. (8): B- Ef fect of H2SO 4 concentration on the absorbance intensity of the complex [Cr (VI)-bipy] at (Cr (VI) =8ppm, pH=4-4.5, λma x=308nm, bipy=0.6mM). IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 Fig. (9): A- Ef fect of CH3COONa concentration on the absorbance intensity of the complex [VO-SH] at (V (IV) =8ppm, pH=5-5.5, λma x=225nm, SH=3mM) Fig. (9): B-Ef fect of H2SO 4 concentration on the absorbance intensity of the complex [V(V)- 8-HQ ] at (V(V) =8p pm, pH=3. 5-4.5, λma x=550nm, 8-HQ =1mM). Fig. (10): Ef fect of time on the absorbance intensity of the complexes (a) [Cr (III, VI) - DPC] at (Cr (VI) =6ppm, pH=8-8.5, λma x =542 nm, DPC=25. 8mM), (b) [Cr (VI)- bipy] at (Cr (VI) =8ppm, pH=4-4.5, λma x=308nm, bipy=0.6mM), (c) [VO-SH] at (V (IV) =8ppm, pH=5-5.5, λma x=225nm, SH=3mM) and (d) [V (V)- 8-HQ ] at (V (V) =8ppm, pH=3. 5-4.5, λma x=550nm, 8-HQ =1mM). Fig. (11): Ef fect of ligh t on the absorbance intensity of complex [Cr (VI)-DPC] at (Cr (VI) =6ppm, pH=8-8.5, λma x =542nm, DPC=25. 8mM) (a) daylight eff ect (b) radiation light eff ect. Fig. (12): Ef fect of temperatures on the absorption intensity of the complex (a) [Cr (VI)-DPC] at (Cr (VI) =6pp m, pH=8-8.5, λma x=542nm, DPC=25. 8mM), (b) [Cr (VI)-bipy] at (Cr (VI) =8ppm, pH=4-4.5, λma x=308nm, bipy=0.6mM), (c) [VO-SH] at (V (IV) =8ppm, pH=5-5.5, λma x=225nm, SH=3mM) and (d) [V (V) - 8-HQ ] at (V (V) = 8pp m, pH=3. 5-4.5, λmax=550nm, 8- HQ =1mM). IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 Fig (13): A- Continuou s variation plot for the complex [Cr (VI)-DPC] at (Cr (VI) =0. 5M, DPC=0. 5M) Fig (13): B- Continuou s variation plot for the [Cr(VI)-bipy] at (Cr(VI)=0.5M, bipy=0.5M) Fig. (13): C-Continuou s variation method for the complex [VO-SH] at (V (IV) =0. 5M, SH=0. 5M) Fig. (13): D- Continuou s variation plot for the complex [V(V)- 8-HQ ] at (V(V)=0. 5M, 8-HQ =0. 5M) Fig. (14): Th e suggested st ructure of the complex es (a) [Chromium-1, 5-diph enylcarbazone] at 1 :2 ratios, (b) [Chromium (VI)-2, 2'-bipyridine] at 1:2 ratios, (c) [VO-thioglycolic acid] at 3:2 ratios an d (d) [Vanadium (V)- ox ine] at 1:2 ratios IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 Fig. (16): A- Standard add ition curve for the determination of Chromium in ex hibition urine sample (1) through the relationship between the amount of chromium added and the amount of absorbance intensity. Fig. (16): B- Standard add ition curve for the determination of chromium in non -ex hibition urine sample (2) through the relationship between the amount of chromium added and the amount of absorbance intensity Fig. (17): A- Standard add ition curve for the determination of chromium in exhibition blood sample (1) through the relationship between the amount of chromium add ed and the amount of absorbance intensity Fig. (17): B- Standard add ition curve for the determination of chromium in non -ex hibition blood sample (2) through the relationship between the amount of chromium add ed and the amount of absorbance intensity. Fig. (15): A-lin ear calib ration curve for determination of (a) Cr (VI) ion with DPC reagent, (b) [Cr (III)] ion with DPC reagent, (c) Cr (VI) ion with 2, 2'-bipyridine reagent. Fig. (15): B-lin ear calibration curve for determination of (a) V (IV) ion with thioglycolic acid reagent and (b) V (V) ion with 8-HQ reagent [Cr(VI), Cr(III )] ppm [V(IV), V(V)] ppm IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L. 23 (3) 2010 Fig. (18): A- Standard add ition curve for the determination of van adium ion in mushrooms sample (1) through the relationship between the amount of vanad ium add ed and the amount of absorbance intensity Fig. (18): B- Standard add ition curve for the determination of vanad ium ion in cereal sample (2) through the relationship b etween the amount of vanad ium add ed and the amount of absorbance intensity. Fig. (18): C - Standard add ition curve for the determination of vanadium ion in strawberry sample (3) through the relationship b etween the amount of vanadium add ed and the amount of absorbance intensity. IHJPAS 2010) 3( 23 مجلة ابن الھیثم للعلوم الصرفة والتطبیقیة المجلد ازالة المتداخالت ودراسة طیفیة لتقدیر الكروم والفنادیوم وتطبیقات أسیل صالح منصور ،*بشرى بشیر قاسم ، أیاد حمزه جاسم ن قسم الكیمیاء، كلیة العلوم، جامعة النهری جامعة بغداد ،لومقسم الكیمیاء، كلیة الع * الخالصة ذج الحیـة وتقـدیر الفنـادیوم الربـاعي والخماسـي فـي النباتـات واالطعمـة طیفیـا اقدر الكروم الثالثـي والسداسـي فـي النمـ Cr (VI)-bipy] ,[Cr (III, VI)-DPC]عـن طریـق تكـوین المعقـدات ], [VO-SH], [V (V)-8-HQ] تكمـا درسـ دراســة و،ثبوتیـة المعقـد فـيكافـة وتأثیرهــا حیـث دراسـة المتغیــرات الفیزیائیـة والكیمیائیـة الظـروف الفضـلى لتكـوین المعقــد مـن واجـراء المعالجـات األحصـائیة الحدیثـة للبیانـات التحلیلیـة ،تحضـیر منحنیـات المعـایرة للمعقـدات المحضـرة و طبیعة المعقدات، ت مـن الناحیـة الداینمیـة الحراریـة مـن خـالل حسـابات میكانیكیة التفاعال تتأثیر المتداخالت وقد فسر تالناتجة كما درس Ece ll , Keq. , ∆G امكانیة ازالة هذه المتداخالت األیونیة باستخدام اعمدة التبادل األیوني تكما درس. مـل.مـایكروغرام) 8-0.5(بمـدى Cr(III), Cr(VI), V(IV), V(V) حضـر منحنـي المعـایرة لتقـدیر -1 ومعامـل V(IV), V(IV), Cr(VI), Cr(III) 20 ،15 ،50 ،100وقـد وجـد ان حـد الكشـف لتقـدیر0.9995 -0.9985 االرتبـاط مـل/نـانوغرام -1 %98.9= وكانـت نسـبة األسـترداد المئـوي لتقـدیر الكـروم السداسـي فـي انموذجـات الـدم واألدرار، علـى التـوالي وقــد تـــم %101.09 ~ %99.24=طعمــة واألســترداد المئــوي لتقـــدیر الفنــادیوم الربـــاعي فــي النباتـــات واأل 100.81%~ .للنتائج التي تم الحصول علیها بالطریقة الطیفیة وطریقة األضافات القیاسیة الحصول على تطابق عال IHJPAS