2010) 3( 23 مجلة ابن الھیثم للعلوم الصرفة والتطبیقیة المجلد -2( – 1التقدیر الطیفي الیون السماریوم الثالثي باستخدام كاشف حامض النفثویك -3-ھیدروكسي -2 –) ازو –بنزوامیدازوالیل ازھار صادق حمودي جامعة بغداد ،ثم ابن الھی -كلیة التربیة ،قسم الكیمیاء الخالصة ع الكاشـف دازوالیل -2( – 1یتفاعل ایون السماریوم الثالثي ـم ك -3-ھیدروكسـي -2-) ازو –بنزومـی حـامض النفثوـی داره اذ امكونا معقد 8في المحیط القاعدي عند دالة حامضیة مقدارھا وجي مـق د طـول ـم الي محمـر عـن ون احمـر برتـق 550ـل دارھا 48الكثر من اان المعقد یكون مستقر وجد، نانومیتر ع امتصاصـیة موالریـة مـق ساعة عند الدالـة الحامضـیة المثلـى ـم مول . ل 7767، 77 -1 سم. -1 10.* ، 635( مع مطاوعة لقانون بیر لمدى من التراكی�ز بح�دود -5 – 35 ،6 *10 -5 ( الري 1: 3فلز بطریقة النسبة المولیة ووجد ان االرتب�اط یك�ون بنس�بة :تم تعیین تكافؤیة المعقد من حیث نسبة الكاشف . مو . �ماریوم الثالث�ي وتب�ین وج�ود تراكی�ز درس تأثیر تداخل عدد االیونات الموجب�ة والس�البة عن�د التق�دیر الطیف�ي الی�ون الس ة تعطي نتائج .مختلفة على قیم االمتصاص امتباینة من االیونات المضاف IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I. VOL. 23 (3 ) 2010 The Spectrophotometric Determination of Samarium (III) With (l-2(2-Benzoinidazoly-AZO)-2-Hydroxy-3- Naphthoic Acid A.S. Hammodi Departme nt of Chemistry , College of Education, I bn Al-Haitham, Unive rsity of Baghdad Abstract Samarium(III) ions react with (l-2(2-benzoinidazolyl-azo)-2-hy droxy -3-nap hthoic acid in basic medium (p H = 8.0) forms a red-orange complex at A.max (550nm). The comp lex was found to be stable for at least 48 hrs. at the given p H. The apparent molar absorp tivity is 7776.77 L.mo l -1 .Cm -1 and a linear calibration curve is obtained in the range (0.639x 10 -5 M - 6.350x 10 -5 M ). The stoichiometry of comp lex was confirmed by using mole ratio method which indicated that ratio of reagent t o metal is 3:1. The effects of the p resence of d ifferent cations and anions as interferences in the determination of samar ium(III) under the given conditions were investigated. Introduction A basic characterist ic of the lanthanide group is the chemical similarity of the individual members. Consequently , data on the total lanthanide content often suffices in p ractical p roblems, p articulary when all the lanthanides behav e similarly , eg. in the p roduction of alloy steels or when the ratio of the individual members is constant (e.g. in geochemistry ). In a search for new sensitive and selective reagents a wide variety of substituents and subgroup s has been introduced on azobenzene and azonap hthalene derivatives in att emp ts to obtain more favorable metal-binding and colorimetric behavior for lanthanide elements, arsenazo-1, arsenazo(III) and dicarboxy -arsenazo(III) [1-3] have been widely used to determine tot al rare earth, but they are suffer from non selectivity . Carboxy nitrazo [4] and arsenazo-p -N02 [5-6] have been also r eported to give sensitive colour reactions with cer ium sub- group elements and to give no, or less sensitive r eactions with y ttrium subgroup elements, but have not been widely used. Numerous sp ectrop hotometric methods based on the use of molecules p ossess hy droxy l group , esp ecially 0,0'- dihydroxy azo comp ound including erichrom b lack T [7], calma gite [8] and Xy lenol oran ge[9], hav e been used to determine total rare earth but none of these procedures is very selective. However atomic absorp tion, atomic emission and high p erformance liqu id chromatogr aphy techniques are vastly sup erior to any of the sp ectrop hotometric p rocedures described to data; so it is clear that furt her work is indicated. The present p ap er rep orts asp ectrop hotometric determination of samar ium(III) usin g a reagent (l-(2-benzoimidazoly I-azo)-2hy droxy -3-nap hthoic) acid which was sy nthesized from 2-aminobenzimidazol and 2-hy droxy -3-napthoic acid as described p reviously [10], and the optimium reaction conditions are ev aluated and excellent metal ion sensitivities are obtained. IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I. VOL. 23 (3 ) 2010 Materials and Methods Apparatus & Reagents: Sp ectrop hotometric measurements were made with LKB-Bouch model NOVA SPEC, with py rex cell of lOmm p ath length was used. The pH was measured on LP-56 p H-meter Aqueous solution of samarium (III) (4.42 x 10 -6 M ) was p rep ared by dissolving 0.0110 gm of (Sm203) in 20 ml (5M ) HN03 and then diluted to 100ml with deionized water. An alcoholic (7.53 x 10 -4 M ) (1-2(2- benzo inidazoly l – azo ) -2- hy droxy l -3- naphthoic acid reagent was p repared by dissolving 0.0625 gm of the reagent in 250 ml ethanol solution and kept in dark room. Buffer solution (p H 4.0) was p repared by mixing 50 ml (0.2 M p otassium hy drogen p hthalate) with 0.4ml (0.2 M KOH) and then diluted to 200ml with deionized water(ll). The p H being adjust ed with few drops of 1M NaOH or 1M HC1. General Procedure: The test solution containing not more than 1.2 ug of samarium was taken in a 10ml volumetric flask; 1ml of buff er solution at p H 6.0 and 5ml of (7.53 x 10 - 4 M ) reagent were added suc cessively and mixed well. The solution was then diluted to the mark with water and the absorbance was measured at 550 nm against reagent blank solution. Results and Discussion Absor ption S pectra: The absorp tion maximu m of the reagent was at 490 nm [figI]. The comp lexes of Samarium have absorp tion maximu m at 540nm at (pH 6.0), and there was no shift in the wavelength when the p H value varied from 5.0 to 8.0 under these conditions samarium forms a red-oran ge coloured comp lex. The formation of the comp lex is accomp anied by a mark ed incr ease in the absorbance and a bathochromic shift of approximately 60nm. Effect of pH: The effect of p H on the absorption of the samarium complex was st udied at 550nm with solution containin g 4 x10 -7 M samarium and 1.12 x 10 -4 M reagent. A p lot of absorbance against p H [Fig 2] showed that t he absorban ce was incr eased gr adually as the pH increased from 5.0 to 8.0 but decr eased r apidly above p H 8.0. T he increase in the absorbance under these condition may be exp lained by an increasin g sensitivity of the reagents at this value of pH t o word Samarium. Reagent Concentration: The effect of the amount of r eagent solution on the absorbance of a series of solutions containing known amount of Sm(III) solution buffered at p H 8.0 are shown in [Fig 3]. It was found t hat (3.76 x 10 -4 M ) of the reagent solution sufficed to complex (9.52 x 10 -5 M ) of Sm with large excess of reagent has deleterious eff ect on the absorbance. S toichiometery of Complex: The stiochiometery of the comp lex has been st udied by the mole-ratio methods [fig 4], the method show that Sm(III) form as 1:3 comp lex (M etal : ligand) with reagents, this is in agreement with (Hamed) observation that reagent form a (1:3) comp lex with La +3 and Eu +3 . Effect of Time: The stability of the comp lex was st udied at laboratory temp erature by measuring the absorbance of regu lar time intervals. The maximu m absorbance was acheived after 5 min and no ch ange was then observed for at least 48hr. Beer . s La w and se nsitivity : The absorbance of Sm(III) comp lex was found to be linear related to the concentration of metal, Beer's Law's was oby ed in the concentration range (0.635 x 10 -5 M - 6.35 x 10 -5 M ) with molar absorpt ivity of (7776.77 L. mol -1 .Cm -1 ). Effect of Forign Ions: The analytical method was app lied to a f ixed amount of Sm(lII) (6ug/ml) in the p resence of var ious amounts of ot her ions. IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I. VOL. 23 (3 ) 2010 The anions examin ed, chloride, nitrate, sulfate and chromate ions showed no interference at all concentration; fluorid e, thiosulfate and citrate ions did not interfere in 50 fold molar amounts , or t artrate and p hosp hate ions in 20 fold amount. The tolerance limits were taken of divalent and trivalent metal ions that caused an error are summar ised in table (1) iron(III), nick el(II), Cerium(III), Zinc(II) and copp er interfered seriously with determination in the (Sm-BIANA) sy stem and their interference can be eleminated by addition (4mg) of ascorbic acid and 4 mg .Pot assium cyanide, so that p rior sep aration would be essential. Re ferences 1. Savvin, S. B, (1963); Zavod. Lab., 29:131. 2. Savvin , S. B.; Prop istsova R. F. and Sterl'-nikova, R. V. Zh. (1969), Anal. Khim., 24. 3. Budesinky, B. and Haas, K.; Fresenius. Z . (1965), Anal. Chem. 210:263 . 4. Savvin , S. B; Petrova, T. V. and Romanov, P. N.(1972), Talanta, 19:1437. 5. Perisic-Janjic, N. U; M uk ,A. A. and Canic, V. D.(1973), Anal. Ch em. 45:798 . 6. Sandell, E. B. and Onishi, H.,(1978), Pht ometric Determination of Traces of M etals, Part 1,4th. ed., J. Wiely . New York, p. 467. 7. Yadvendr a, K. and Panavelil ,T.(1987), Analy st , July , 112: 1015 . 8. Dewet ,W. J. and Behrens, G. B.;(1968), Anal. Chem; 40 :200 . 9. Britt ain H. G. (1979), Anal. Chim. Acta 106:401. 10. Al-obaidi ,F. N.; Salah ,H. A., Al-Kadimi, A. H.and Abdulla, M (1989),Analyst, 2; 53-71 . 11. Vo gel 1.. A t ext book of macro and se mimicro qualitative in or ganic analy sis ,4t h. edn.(1959) Page 645 12. Hamed, A.J. ,(2000) Ms.C thesis, Baghdad University , The Sp ectrop hotometric Determination of Lanthanum ion and Europ ium with (1-.2(2- Benzoinidazolyl-azo ) -2- Hy droxy -3- Nap hthoic Acid) Table (1) :Effect of foreign ions for the determinati on of 6ug/ml Samarium(III) Ion Amount pp m Sm +3 Found (p.g) Error % Fe +3 1.2 5.10 -15.0 Wi+2 0.8 6.4 +6.6 Zn+i 1.6 5.30 + 11.6 Cu +i 2 6.4 +6.60 Ce Ki 4 8.2 +36.6 IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I. VOL. 23 (3 ) 2010 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 420 430 440 450 460 470 480 490 500 510 520 530 540 550 560 570 580 590 600 Wave Length ( nm ) A b s o rb a n c e A B 0 0. 1 0. 2 0. 3 0. 4 0. 5 0. 6 0. 7 0. 8 0. 9 1 4 5 6 7 8 9 10 11 pH A b s o r b a n c e Fig .(2) : Effect of pH on absorbance me asured at 550 nm . 0 0. 1 0. 2 0. 3 0. 4 0. 5 0. 6 0. 7 0. 8 0 1 2 3 4 5 6 Concentration ( M ) x10 -4 Fig. (3) : Effect of reagent concentration on the formation of Samarium (III) complex. Fig (1) : Absorbanc e Spectra A : R eagent blank measured against deionized water. B : Sam arium com plex measured against reagent blank A b so rb an ce IHJPAS IBN AL- HAITHAM J. FO R PURE & APPL. SC I. VOL. 23 (3 ) 2010 0 0.1 0.2 0.3 0.4 0.5 0.6 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 M oles of re agent/Mo le s o f samarium(III) A b s o rb a n c e Fig. ( 4 ) : Mole Ratio IHJPAS