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Acenaphthenequinone monoxime(AQM) as a selective reagent for the spectrophotometric determination of platinum(IV) by solvent extraction
248
SHORT
COMMUYICATIONS
BIBLIOGRAPHIE
1 A N Lange et A. L Ward. J Ant C/rem Sot. 1925. 47. 1000 2 W Fresenms et G Jander, Handbrrch der anul\t~schet~ Chemle. Tell III. Bd VII d. p S-IO-13 et p 55&551, p 582-586, Springer-Verlag, Berlm, 1967 3 K. Johannesson, Anal. Chem.. 1956. 28. 1475 4 J Bognar, L Nagy, Mikrochzm. Acfa., 1968, 108. 5 B. K Yatstmtrskn, L I Budarm, N A. Blagoveshchenslcaya, R. V Smlrnova. A P Federoca et V K. Yatstmtrsku, Zh Analu Khlm., 1963, 18, 103 6. N H Furman, Standard Methods of Chemtcal Analysis, 6th Ed, Vol I. p 523. Van Nostrand, New York, 1962 7 M L Kulberg, Orgamcheskte reactwl u anahttceskor hlmu. Goskhlmtzdat, Mobcow, 1950 8 Gh Ghtmtcescu et Cameha Musta@. Studio $1 Cercet St Acad RPR, FII IaJt. 1954. 5. 1 9 S. Utsumt, M. Shiota. N Yonchara et J Jwasakt, Nippon Kagaku Zasshl, 1964. 85. 32 10. E I. Savtchev. 1. G. Vastl’eva et E. I. Golovm, Zauodsk Lab., 1963, 29, 1433 Resume--Un microdosage de l’ton I- dans Ies eaux et les produtts orgamques est fondt sur son oxydatton par l’eau oxygen&e en lode, qut dtveloppe avec l’o-tohdme a pH 3.554,5 une coloratton bleue. Sa senstbthte est de 0,02 fig I-/ml Summary-A mtcrodetermmatton of Iodide m waters and organic materials IS based on oxtdation with hydrogen peroxide to todme which gtves a blue colour with o-tohdme at pH 3 5-4 5 The sensitivity IS 0 02 pg/ml.
Zusammenfassung-Elne Mikroermtttlung von Jodid m Wasser und m orgamschen Stoffen grdndet such auf Oxydierung mtt Wasserstoffperoxtd zu Jod, was eme blaue Farbung mtt o-Tohdm bet pH 3,5-4,5 ergtbt. Dte Genautgkett 1st 0,02 fig/ml. Tulmta,
Vol 20. pp 248-251
PerBamon Press. 1973 Pnnred 2” Great Brlram
ACENAPHTHENEQUINONE MONOXIME(AQM) AS A SELECTIVE REAGENT FOR THE SPECTROPHOTOMETRIC DETERMINATION OF PLATINUM(IV) BY SOLVENT EXTRACTION (Recewed
31 December
1971. Accepted
31 May 1972)
Reviews of method&j for the colortmetric determmatton of platmum show that there IS a real need for a reagent which can be used to determine platmum, parttcularly m the presence of other platmum metals. cobalt, nrckel and copper Acenaphthenequmone monoxtme. which has already been used for the spectrophotometric determmatton of ruthenmm,s osmtum,6 rhodium’ and cobalt” was examined to see If it satisfies this need. EXPERIMENTAL
Reagents Standard platmum solution was prepared by dtssolvmg 1 g of grade I platinum thermocouple wue (99.99”; pure) in hot aqua regra The resultant solutton was evaporated almost to dryness. 4 small amount of hydrochloric acid was added and the solutton was again evaporated to dryness. The treatment was repeated three or four times m order to destroy any mtroso complexes After the final evaporatton. 5 ml of hydrochlortc acid were added and the solutton was made up to 500 ml with doubly dtstilled water More dilute solutions were prepared, as needed, by dilution of the stock solutton Two standard platmum soluttons prepared by exactly the same procedure were found to give the same spectrophotometnc readings Acenaphthenequmone monoxtme (AQM) O.lM solution in ethanol Chloroform, reagent grade, was used after distillatton Buffer soluttons with pH values ranging up to 5.0 were prepared by mixmg 0.5M acetic acid and 0 5M sodtum acetate m different proportions Procedure The pH ofa solutton contammg 19.5-156.0 pg of platinum and 2 ml of 1 x IO’- M reagent solution is adJusted to between pH 1 9 and 3 2 with acetic acid-sodium acetate buffer (5 ml) and dtluted to 10 ml with doubly dtstdled water (The acid present m the platmum solution accounts for the low pH values) The contents
SHORT
COMMUNICATIONS
249
are heated for 2 hr on a bodmg water-bath, then cooled to room temperature, and 10 ml of chloroform are added The contents are equihbrated by shakmg for 5 mm and then left for 1 mm to allow the two phases to separate. The organic phase IS separated and centnfuged to remove water droplets, and the absorbance IS measured against the corresponding reagent blank prepared under identical conditions From the absorbance, the amount of platmum IS deduced from the calibration curve. RESULTS
AND
DISCUSSION
Optvnum condulons
The rate of reaction of platmum(IV) with AQM IS slow at room temperature, but It increases at loo”, the absorbance of the chloroform extracts becoming constant after about 2 hr The absorbance remains constant over the pH range 1.0-3.2, so a buffer solution of pH 2 5 k 0.1 was adopted for the working procedure. At pH 2.5 an eightfold molar excess of the reagent IS sufficient for full colour development However, a tenfold molar excess of the reagent was generally employed Optical constants and composltlon of the complex
The absorption spectra are shown m Fig 1. All measurements were made at 390 nm The extraction procedure was followed and the absorbance of the orgamc phase was measured Beer’s law was obeyed up to 23.4 ppm of platinum. The accurate range for determination of platinum, as evaluated from a Rmgbom plot, 1s 1.95-156 ppm of plabnum, and the sensitivity of the reaction at 390 nm IS Oa21 pg/cm’ for log lo/l = @Ol. The colour IS stable for at least 24 hr. Eight determinations on a solution of 11 7 ppm of platinum resulted in a mean absorbance of 0.566 with an average relative deviation of L-0.2%. The method of contmuous variahons’.” and the mole-ratio method’ ’ were employed to establish the stoicluometry of the complex Both complexes showed the ‘existence of 1 .2 (Pt. AQM) complex Efiect of dwerse tons The effect of foreign ions on the determination of platinum was studied by adding known amounts of foreign ions to samples containing 15.6 ppm of platinum and extracting the complex mto chloroform by the working procedure Interference from large amounts of ruthenium(III), osmmm(VIII), rho&um(III) and Iridmm(III) ions was sufficient to warrant their removal, but they could be tolerated at the IO-ppm level Tartrate and citrate have been successfully used as masking agents for some metals, Since they themselves are tolerated even in large amounts Oxalate has also been used as a masking agent but since oxalate interferes, a relatively small excess was used Results of the study of diverse Ions are shown m Table 1. Deternunatron of platmum m presence of palladium
The reaction between platmum and acenaphthenequmone monoxlme takes place at elevated temperatures while palladium is completely precipitated at room temperature. Based on thrs behavlour of the two metals,
Fig 1 Absorption spectra of platmum-AQM complex Platinum, 1 x 10m4M, reagent, 15 x 10m4M A Reagent L’Schloroform B Platmum-AQM complex us. reagent
250 Table 1. Determination of platmum m presence of foreign ions Amount of Pt = 15 60 ppm; p&I = 2a Absorbance in absence of foreign ions = 0~752
Farergn ran Sulphate Cttrate Tartrate Nitrate Phosphate Pyrophosphate Perchlorate Nitrate Borate Ffuonde Thiocyanate Oxalate Bromate Zinc(H) CadmmmfII) NickeHII) CobaIt(f1) Magn~Ium~II)
Amount of foreign ion added, @J=
Absorbance
I80
0.752 0.752 0.752 0.752 0,752 0.751 0.752 a752 @7S4 0.760 0,765 076s 0.740 0.760 0.765 o-752 Q752 0.752
Amount of foreign Devta non
1OIl
abso~a~e
added, ppm
Foreign ton
omo
0000 OdOO
Qouo
om -0001
0000 OQOO
+0*2 +0*008 +O@f3 i-o.013 -0*012 f0008 +0@013 OaoO OGOO O.000
Strontmm(I1) Barmm(I1) Calcium(I1) CopperfII) ~ran~~rn~VT) Iron(II1) Silver(I) Ruthenmm(III)t Rhodium(iII)t Iridmm(III) Qsm~urn~V~~ GoId( III) Vanadium(V) Molybdenum(V1) Mercury(II)$ Chrom~um~III) Tho~~rn~I~~ Lead@]
600 600 600 60 230 tOO 34 10 10 IO IO 30 54 20 34 z 40
Absorbance 0754 0 754 0.754 0.758 O-752 0.752 0.760 0,753 0.754 0 754 0 754 0.752 0.752 0.752 0.761 0.752 O,fSO 0770
Deviation m absorbance + 0.002 +0002 +0002 + oM16 oooo OGOO + OGG8 +0001 f 0.002 to002 +0*(x)2 O@O 0.000 OGOO + 0*009 0GOO iOOO8 +O*OtS
* Oxaiate used as maskmg agent t Citrate used as masking agent g Fluonde used as masking agent paRadium was extracted mto chloroform before heatmg. The remammg aqueous soIunon was heated for 2 hr and the piatmum complex was extracted into chloroform. The absorbance of the extracted complex was identxcal with that found m absence of palladmm. The results are recorded m Table 2. Compartson wed other methods’-4 The ~n]trosodirnethy~anI~~n~lod~de method IS more sensitive but iess selective than a~naphtbeuequlnone monoxrme and zt requires more reagent and IS more sensttrve to the trme of heatm, change of pH and the amount of buffer. The AQM method ISless senstttve than those based on tm(I1) chlottde and o-phenylenedtamme, but tt is more selective. Acknowledgement-One of the authors (SKS) ts thankful to the Counctl of Scientific and Industrial Research (Indta) for the award of a fefiowship Table 2. ~te~inat~u of ptatmum m presence of palladium Absorbance m absence of palladium = 0 752
Palladmm. 100 200 30.0 40.0 50-O 60% Department Of Chemrstry Unwerstty of Delhi Driht-7 fndra
ppm
Piatmum, ppm
Absorbance after separati5n
IS6 156 15.6 15.6 15.6 156
0 752 0.749 0.751 0 752 o-7.5$ 0 752
S K SINDHWANI R P SINGEi
SHORT
COMMUNlCATlONS
251
REFERENCES
1 2 3. 4 5 6 7 8 9 10 11
F. E Beamtsh, Talanta, 1965, 12, 743 F E Beamrsh and W A E. McBryde, Anal. Chum Actn, 1953,9, 349, 1958, 18, 551. F E. Beamrsh, The Analytxal Chemtstry of the Noble Metals. Pergamon, London, 1966 F. E Beamtsh and J. C. Van Loon, Recent Advances tn the Annlytlcol Chemtstry of the Noble Metals, Pergamon, London, 1972 S K Smdhwani and R P. Smgh, Anal Chum Actu, 1971, 55, 409. Idem, Mrcrochem. J., 1971, 16. ldem, ibrd.. 1971. 16. 1016. Idem, Sepn SCI.. m the press P Job. Ann Chum. (Pans). 1928,9, 113 H Irving and T. B Prerce, J. Chem. Sot., 1959, 2565 J H Yoe and A. L Jones, Ind Eng. Chem. Anul Ed., 1944, 16, 11I. Summary-Acenaphtheneqmnone monoxtme has been found to be a selecttve reagent for spectrophotometrrc determmatton of l-16 ppm of platmum m the pH range 1.90-3.20. With excess of the reagent, a 1 2 (metal : hgand) complex is formed with an absorptron maxtmum at 390 nm and molar absorptrvity of 9.0 x lo3 1mole-‘cm- r. The effect of foreign ions has been mvestrgated and other platmum metals do not interfere if present in srmrlar amounts to the platinum Zusammeufassung-Es wurde gefunden, daD Acenaphthenchmonmonoxrm ein selektives Reagens zur spektrophotometnschen Bestrmmung von I-16 ppm Platm bet pH 190-3 20 1st Mit emem Reagensuberschug wrrd em 1 . Z(Metall:Ltgand)-Komplex mrt Absorpttonsmaximum bei 390 nm und emem molaren Extmktionskoeffiaenten von 9G x 10” 1 mol-’ cm-’ gebildet. Der EinfluD von Fremdtonen wurde untersucht. andere Platmmetalle storen mcht, wenn ste m ahnlichen Mengen wre Platm vorhegen R&urn&On a trouvt que la monoxrme de l’actnaphtbnequmone est un reactif selectif pour le dosage spectrophotomttrrque de 1-16 p.p.m de platme darts le domame de pH 1,90-3.20 Avec un excis de reacttf, il se forme un complexe 1 : 2 (metal : coordmat) avec un maxrmum d’absorptton a 390 nm et un coefficient d’absorptron molatre de 9,0 x 10’ 1 mole-’ cm-‘. On a budre l’mfluence d’rons &rangers et les autres metaux de la mme du platme ne g&-tent pas ~‘11ssont presents en quantitb simtlaires au platme
TalonraVol
20. pp 251-254
TELLURATE
Pcrgamon
Press
1973 Prmlcd m Great Bntam
AND PERIODATE SOLUTIONS AS MEDIA FOR PAPER ELECTROPHORESIS OF CARBOHYDRATES (Recemed 3 July 1972. Accepted 29 August 1972)
Some years ago one of us1 described an exploratory study of the electrophoretrc behaviour of sugars and other polyhydroxy compounds m 0.05M tellurrc acid adJusted to pH 8-11 wrth sodium hydroxide. Although the compounds were found to migrate as anions, considerable elongation of spots was observed and the method was not recommended at that trme as an analytical techmque smce far better separations were obtamed by using other complex-forming electrolytes * The continumg interest m electrophoretic separanon of polyols, as shown by perrodrc reviews of the subJect, 3 4 has prompted us to re-examme the use of te!lurate solutrons m an attempt to find condrtrons under whrch they could be employed as satrsfactory complexmg medra Extensive studtes of the thermodynamrcs and kmetrcs of the polyol-tellurate reactron have been reported by Edwards and co-workers, who showed that a 1 . 1 amomc complex forms5 but at a rate which IS rather low compared to the very rapid reactton occurnng in borate solutrons, the most popular me&a for electrophoresrs of polyols Although the formation constant for the polyol-tellurate complex decreases with increase m temperature6 the reactton IS base-catalysed and its rate increases markedly with the temperature ’ In the absence of strong adsorption upon the support medium, an elongation of polyol spots dunng electrophoresls may be reasonably ascribed to mcompleteness of complexmg. Thus, the above-mentioned studies would suggest that a suttable modrficatton m pH, concentratron of tellurate, and temperature, might provide better condrttons for complex formation and lead to more ducrete spots. One of the obJects of the present work was to test this posstbrhty experrmentally
SHORT
COMMUYICATIONS
BIBLIOGRAPHIE
1 A N Lange et A. L Ward. J Ant C/rem Sot. 1925. 47. 1000 2 W Fresenms et G Jander, Handbrrch der anul\t~schet~ Chemle. Tell III. Bd VII d. p S-IO-13 et p 55&551, p 582-586, Springer-Verlag, Berlm, 1967 3 K. Johannesson, Anal. Chem.. 1956. 28. 1475 4 J Bognar, L Nagy, Mikrochzm. Acfa., 1968, 108. 5 B. K Yatstmtrskn, L I Budarm, N A. Blagoveshchenslcaya, R. V Smlrnova. A P Federoca et V K. Yatstmtrsku, Zh Analu Khlm., 1963, 18, 103 6. N H Furman, Standard Methods of Chemtcal Analysis, 6th Ed, Vol I. p 523. Van Nostrand, New York, 1962 7 M L Kulberg, Orgamcheskte reactwl u anahttceskor hlmu. Goskhlmtzdat, Mobcow, 1950 8 Gh Ghtmtcescu et Cameha Musta@. Studio $1 Cercet St Acad RPR, FII IaJt. 1954. 5. 1 9 S. Utsumt, M. Shiota. N Yonchara et J Jwasakt, Nippon Kagaku Zasshl, 1964. 85. 32 10. E I. Savtchev. 1. G. Vastl’eva et E. I. Golovm, Zauodsk Lab., 1963, 29, 1433 Resume--Un microdosage de l’ton I- dans Ies eaux et les produtts orgamques est fondt sur son oxydatton par l’eau oxygen&e en lode, qut dtveloppe avec l’o-tohdme a pH 3.554,5 une coloratton bleue. Sa senstbthte est de 0,02 fig I-/ml Summary-A mtcrodetermmatton of Iodide m waters and organic materials IS based on oxtdation with hydrogen peroxide to todme which gtves a blue colour with o-tohdme at pH 3 5-4 5 The sensitivity IS 0 02 pg/ml.
Zusammenfassung-Elne Mikroermtttlung von Jodid m Wasser und m orgamschen Stoffen grdndet such auf Oxydierung mtt Wasserstoffperoxtd zu Jod, was eme blaue Farbung mtt o-Tohdm bet pH 3,5-4,5 ergtbt. Dte Genautgkett 1st 0,02 fig/ml. Tulmta,
Vol 20. pp 248-251
PerBamon Press. 1973 Pnnred 2” Great Brlram
ACENAPHTHENEQUINONE MONOXIME(AQM) AS A SELECTIVE REAGENT FOR THE SPECTROPHOTOMETRIC DETERMINATION OF PLATINUM(IV) BY SOLVENT EXTRACTION (Recewed
31 December
1971. Accepted
31 May 1972)
Reviews of method&j for the colortmetric determmatton of platmum show that there IS a real need for a reagent which can be used to determine platmum, parttcularly m the presence of other platmum metals. cobalt, nrckel and copper Acenaphthenequmone monoxtme. which has already been used for the spectrophotometric determmatton of ruthenmm,s osmtum,6 rhodium’ and cobalt” was examined to see If it satisfies this need. EXPERIMENTAL
Reagents Standard platmum solution was prepared by dtssolvmg 1 g of grade I platinum thermocouple wue (99.99”; pure) in hot aqua regra The resultant solutton was evaporated almost to dryness. 4 small amount of hydrochloric acid was added and the solutton was again evaporated to dryness. The treatment was repeated three or four times m order to destroy any mtroso complexes After the final evaporatton. 5 ml of hydrochlortc acid were added and the solutton was made up to 500 ml with doubly dtstilled water More dilute solutions were prepared, as needed, by dilution of the stock solutton Two standard platmum soluttons prepared by exactly the same procedure were found to give the same spectrophotometnc readings Acenaphthenequmone monoxtme (AQM) O.lM solution in ethanol Chloroform, reagent grade, was used after distillatton Buffer soluttons with pH values ranging up to 5.0 were prepared by mixmg 0.5M acetic acid and 0 5M sodtum acetate m different proportions Procedure The pH ofa solutton contammg 19.5-156.0 pg of platinum and 2 ml of 1 x IO’- M reagent solution is adJusted to between pH 1 9 and 3 2 with acetic acid-sodium acetate buffer (5 ml) and dtluted to 10 ml with doubly dtstdled water (The acid present m the platmum solution accounts for the low pH values) The contents
SHORT
COMMUNICATIONS
249
are heated for 2 hr on a bodmg water-bath, then cooled to room temperature, and 10 ml of chloroform are added The contents are equihbrated by shakmg for 5 mm and then left for 1 mm to allow the two phases to separate. The organic phase IS separated and centnfuged to remove water droplets, and the absorbance IS measured against the corresponding reagent blank prepared under identical conditions From the absorbance, the amount of platmum IS deduced from the calibration curve. RESULTS
AND
DISCUSSION
Optvnum condulons
The rate of reaction of platmum(IV) with AQM IS slow at room temperature, but It increases at loo”, the absorbance of the chloroform extracts becoming constant after about 2 hr The absorbance remains constant over the pH range 1.0-3.2, so a buffer solution of pH 2 5 k 0.1 was adopted for the working procedure. At pH 2.5 an eightfold molar excess of the reagent IS sufficient for full colour development However, a tenfold molar excess of the reagent was generally employed Optical constants and composltlon of the complex
The absorption spectra are shown m Fig 1. All measurements were made at 390 nm The extraction procedure was followed and the absorbance of the orgamc phase was measured Beer’s law was obeyed up to 23.4 ppm of platinum. The accurate range for determination of platinum, as evaluated from a Rmgbom plot, 1s 1.95-156 ppm of plabnum, and the sensitivity of the reaction at 390 nm IS Oa21 pg/cm’ for log lo/l = @Ol. The colour IS stable for at least 24 hr. Eight determinations on a solution of 11 7 ppm of platinum resulted in a mean absorbance of 0.566 with an average relative deviation of L-0.2%. The method of contmuous variahons’.” and the mole-ratio method’ ’ were employed to establish the stoicluometry of the complex Both complexes showed the ‘existence of 1 .2 (Pt. AQM) complex Efiect of dwerse tons The effect of foreign ions on the determination of platinum was studied by adding known amounts of foreign ions to samples containing 15.6 ppm of platinum and extracting the complex mto chloroform by the working procedure Interference from large amounts of ruthenium(III), osmmm(VIII), rho&um(III) and Iridmm(III) ions was sufficient to warrant their removal, but they could be tolerated at the IO-ppm level Tartrate and citrate have been successfully used as masking agents for some metals, Since they themselves are tolerated even in large amounts Oxalate has also been used as a masking agent but since oxalate interferes, a relatively small excess was used Results of the study of diverse Ions are shown m Table 1. Deternunatron of platmum m presence of palladium
The reaction between platmum and acenaphthenequmone monoxlme takes place at elevated temperatures while palladium is completely precipitated at room temperature. Based on thrs behavlour of the two metals,
Fig 1 Absorption spectra of platmum-AQM complex Platinum, 1 x 10m4M, reagent, 15 x 10m4M A Reagent L’Schloroform B Platmum-AQM complex us. reagent
250 Table 1. Determination of platmum m presence of foreign ions Amount of Pt = 15 60 ppm; p&I = 2a Absorbance in absence of foreign ions = 0~752
Farergn ran Sulphate Cttrate Tartrate Nitrate Phosphate Pyrophosphate Perchlorate Nitrate Borate Ffuonde Thiocyanate Oxalate Bromate Zinc(H) CadmmmfII) NickeHII) CobaIt(f1) Magn~Ium~II)
Amount of foreign ion added, @J=
Absorbance
I80
0.752 0.752 0.752 0.752 0,752 0.751 0.752 a752 @7S4 0.760 0,765 076s 0.740 0.760 0.765 o-752 Q752 0.752
Amount of foreign Devta non
1OIl
abso~a~e
added, ppm
Foreign ton
omo
0000 OdOO
Qouo
om -0001
0000 OQOO
+0*2 +0*008 +O@f3 i-o.013 -0*012 f0008 +0@013 OaoO OGOO O.000
Strontmm(I1) Barmm(I1) Calcium(I1) CopperfII) ~ran~~rn~VT) Iron(II1) Silver(I) Ruthenmm(III)t Rhodium(iII)t Iridmm(III) Qsm~urn~V~~ GoId( III) Vanadium(V) Molybdenum(V1) Mercury(II)$ Chrom~um~III) Tho~~rn~I~~ Lead@]
600 600 600 60 230 tOO 34 10 10 IO IO 30 54 20 34 z 40
Absorbance 0754 0 754 0.754 0.758 O-752 0.752 0.760 0,753 0.754 0 754 0 754 0.752 0.752 0.752 0.761 0.752 O,fSO 0770
Deviation m absorbance + 0.002 +0002 +0002 + oM16 oooo OGOO + OGG8 +0001 f 0.002 to002 +0*(x)2 O@O 0.000 OGOO + 0*009 0GOO iOOO8 +O*OtS
* Oxaiate used as maskmg agent t Citrate used as masking agent g Fluonde used as masking agent paRadium was extracted mto chloroform before heatmg. The remammg aqueous soIunon was heated for 2 hr and the piatmum complex was extracted into chloroform. The absorbance of the extracted complex was identxcal with that found m absence of palladmm. The results are recorded m Table 2. Compartson wed other methods’-4 The ~n]trosodirnethy~anI~~n~lod~de method IS more sensitive but iess selective than a~naphtbeuequlnone monoxrme and zt requires more reagent and IS more sensttrve to the trme of heatm, change of pH and the amount of buffer. The AQM method ISless senstttve than those based on tm(I1) chlottde and o-phenylenedtamme, but tt is more selective. Acknowledgement-One of the authors (SKS) ts thankful to the Counctl of Scientific and Industrial Research (Indta) for the award of a fefiowship Table 2. ~te~inat~u of ptatmum m presence of palladium Absorbance m absence of palladium = 0 752
Palladmm. 100 200 30.0 40.0 50-O 60% Department Of Chemrstry Unwerstty of Delhi Driht-7 fndra
ppm
Piatmum, ppm
Absorbance after separati5n
IS6 156 15.6 15.6 15.6 156
0 752 0.749 0.751 0 752 o-7.5$ 0 752
S K SINDHWANI R P SINGEi
SHORT
COMMUNlCATlONS
251
REFERENCES
1 2 3. 4 5 6 7 8 9 10 11
F. E Beamtsh, Talanta, 1965, 12, 743 F E Beamrsh and W A E. McBryde, Anal. Chum Actn, 1953,9, 349, 1958, 18, 551. F E. Beamrsh, The Analytxal Chemtstry of the Noble Metals. Pergamon, London, 1966 F. E Beamtsh and J. C. Van Loon, Recent Advances tn the Annlytlcol Chemtstry of the Noble Metals, Pergamon, London, 1972 S K Smdhwani and R P. Smgh, Anal Chum Actu, 1971, 55, 409. Idem, Mrcrochem. J., 1971, 16. ldem, ibrd.. 1971. 16. 1016. Idem, Sepn SCI.. m the press P Job. Ann Chum. (Pans). 1928,9, 113 H Irving and T. B Prerce, J. Chem. Sot., 1959, 2565 J H Yoe and A. L Jones, Ind Eng. Chem. Anul Ed., 1944, 16, 11I. Summary-Acenaphtheneqmnone monoxtme has been found to be a selecttve reagent for spectrophotometrrc determmatton of l-16 ppm of platmum m the pH range 1.90-3.20. With excess of the reagent, a 1 2 (metal : hgand) complex is formed with an absorptron maxtmum at 390 nm and molar absorptrvity of 9.0 x lo3 1mole-‘cm- r. The effect of foreign ions has been mvestrgated and other platmum metals do not interfere if present in srmrlar amounts to the platinum Zusammeufassung-Es wurde gefunden, daD Acenaphthenchmonmonoxrm ein selektives Reagens zur spektrophotometnschen Bestrmmung von I-16 ppm Platm bet pH 190-3 20 1st Mit emem Reagensuberschug wrrd em 1 . Z(Metall:Ltgand)-Komplex mrt Absorpttonsmaximum bei 390 nm und emem molaren Extmktionskoeffiaenten von 9G x 10” 1 mol-’ cm-’ gebildet. Der EinfluD von Fremdtonen wurde untersucht. andere Platmmetalle storen mcht, wenn ste m ahnlichen Mengen wre Platm vorhegen R&urn&On a trouvt que la monoxrme de l’actnaphtbnequmone est un reactif selectif pour le dosage spectrophotomttrrque de 1-16 p.p.m de platme darts le domame de pH 1,90-3.20 Avec un excis de reacttf, il se forme un complexe 1 : 2 (metal : coordmat) avec un maxrmum d’absorptton a 390 nm et un coefficient d’absorptron molatre de 9,0 x 10’ 1 mole-’ cm-‘. On a budre l’mfluence d’rons &rangers et les autres metaux de la mme du platme ne g&-tent pas ~‘11ssont presents en quantitb simtlaires au platme
TalonraVol
20. pp 251-254
TELLURATE
Pcrgamon
Press
1973 Prmlcd m Great Bntam
AND PERIODATE SOLUTIONS AS MEDIA FOR PAPER ELECTROPHORESIS OF CARBOHYDRATES (Recemed 3 July 1972. Accepted 29 August 1972)
Some years ago one of us1 described an exploratory study of the electrophoretrc behaviour of sugars and other polyhydroxy compounds m 0.05M tellurrc acid adJusted to pH 8-11 wrth sodium hydroxide. Although the compounds were found to migrate as anions, considerable elongation of spots was observed and the method was not recommended at that trme as an analytical techmque smce far better separations were obtamed by using other complex-forming electrolytes * The continumg interest m electrophoretic separanon of polyols, as shown by perrodrc reviews of the subJect, 3 4 has prompted us to re-examme the use of te!lurate solutrons m an attempt to find condrtrons under whrch they could be employed as satrsfactory complexmg medra Extensive studtes of the thermodynamrcs and kmetrcs of the polyol-tellurate reactron have been reported by Edwards and co-workers, who showed that a 1 . 1 amomc complex forms5 but at a rate which IS rather low compared to the very rapid reactton occurnng in borate solutrons, the most popular me&a for electrophoresrs of polyols Although the formation constant for the polyol-tellurate complex decreases with increase m temperature6 the reactton IS base-catalysed and its rate increases markedly with the temperature ’ In the absence of strong adsorption upon the support medium, an elongation of polyol spots dunng electrophoresls may be reasonably ascribed to mcompleteness of complexmg. Thus, the above-mentioned studies would suggest that a suttable modrficatton m pH, concentratron of tellurate, and temperature, might provide better condrttons for complex formation and lead to more ducrete spots. One of the obJects of the present work was to test this posstbrhty experrmentally