Short communications 525

Zusammenfassung-Ein Verfahren zur Infrarot-Bestimmung von Calcium oder Lithium neben Strontium oder Barium wird vorges- chlagen. Ein Gemisch der Nitrate wird mit Aceton behandelt, das nur Calciumoder Lithium~trat I&t. Strontium- oder Bariumnitrat wird abfiltriert. Das Filtrat wird mit einem trockenen Luftstrom auf etwa 2 ml eingeengt und mit Aceton auf 5 ml verdtinnt. Das Infrarotapek- trum wird von 86&8OO~m-~ repristriert und die Nitratbande bei 824 cm-l ftir Calcium und 827 crn’ftir Lithium gemessen. Empfohlen werden l-80me Calcium-oder Lithiumnitrat neben bis zu 2OOme Strontium- ode~Bariumnitrat.

0

R&sum&On propose une methode pour le dosage infra-rouge du calcium ou du lithium en presence de strontium ou de baryum. On traite un m&.nge des nitrates a pa&one qui dissout settlement te nitrate de calcium ou de lithi~. Le nitrate de strontium ou de baryum est &par& par filtration. On evapore le Ntrat a 2 ml environ par un courant d’air set puis dilue a 5 ml par Pa&tone. Le spectre infra-rouge est examine de 860 a 800 cm-l et I’on mesure le pit du nitrate a 824 cm-l pour le calcium et 827 cm-l pour le lithium. Le domaine recommand6 est de l-80mg de nitrate de calcium ou de lithium en presence de quantites de nitrate de strontium ou de baryum pouvant atteindre 200 mg.

REFERENCES

1. R. N. Shreve, C. H. Watkins and J. C. Browning, Ind. Eng. Chem., Anal. Ed., 1939,11,215. 2. P. B. Stewart and K. A. Kobe, ibid., 1942,14,298. 3. M. M. Tillu and M. S. Telang, J. Indian Chem. Sot., 1942, 19, 231. 4. C. C. Addison and N. Logan, Advan. Inorg. Chem. Rodiochem., 1964, 6, 89,98.

Taianta, 2969, Vol. 16, pp. 525 to 529. PerSamon Prcs~. Printed in Northern Ireland

Liqui~liquid extraction of tungsten(W) with me&y1 oxide

Application to an alloy steel

(Received 1 July 1968. Accepted 19 November 1968)

MES~TYL oxide (4-methyl-3-pentene-2-one) has been used in this laboratory for the extraction of transition elements. These studies have been extended to tungsten(VI), which can beextracted with 75 % mesityl oxide in isobutyl methyl ketone (ZBMK). It eat-r then be stripped with ammonia and determined photometrically as the thiocyanate complex. The method is simple and rapid and has been successfully applied to an alloy steel.

EXPERIMENTAL

Reagents

Mesityl oxide. Stock solution of sodium tungstate, 48% W/V, standardized by the oxinate method, and

diluted as required for working solutions. Potassium thiocyanate solution, 50% w/v. Tin(H) chloride solution, 20% w/v in concentrated hydrochloric acid.

General procedure

A 2-ml portion of sodium tungstate solution containing 430 pg of tungsten(VI) was taken in a separatory-funnel. Enough hydrochloric acid and lithium chloride were added to make their con- centrations 1M and 12M respectively in a total volume of 25 ml. The aqueous phase was then extracted with 10 ml of 75 % mesityl oxide solution in IBMK for 2 min. The layers were allowed to separate, and tungsten~~ was stripped from the organic layer by shaking first with 10 ml of 05M ammonia and then 5 ml of distilled water. To the extract about 25 ml of concentrated hydrochloric acid, 5 ml of 20% tin(H) chloride solution and 0.5 ml of 12% titanium(III) chloride solution were added and mixed well. After addition of 1.5 ml of 50% potassium thiocyanate solution and dilution

526 Short communications

to 50 ml, the absorbance of the yellow solution was measured photometrically at 420 mu against water, within 2 hr.’

RESULTS AND DISCUSSION

In the presence of 12Mlithium chloride as salting-out agent, extraction was found to be complete from 1-4M hydrochloric acid.

The concentration of mesityl oxide was varied from 19% (1.62M) to 100% (&70M) with IBMK as the diluent, and the hydrochloric acid concentration was varied from 0.1 to 4.OM in the presence of 12M lithium chloride. The results (Table I) show that it is quite possible to extract tungsten(V1) quantitatively even with 75% mesityl oxide. Various other solvents such as chloroform, carbon tetrachloride, benzene, toluene, xylene, n-butanol and isobutyl acetate were also tried as the diluent. The extraction was incomplete with all except xylene, toluene and IBMK. IBMK was preferred as it permits clear separation of the two phases.

The chlorides of lithium, magnesium and aluminium were tried as salting-out agents (Table II)

TABLE I.-DISTRIBUTION RATIO AS THE FUNCTION OF ACIDITY

Mesityl oxide concentration, ‘A

(1i;M)

Initial [HCll, M

0.1 0.2 0.5 1 2-3 4

Extraction, %

462 52.8 61.1 69.4 75.0 80.6

(2.:M) 0.1 0.2 0.5 1

f 4

(5a:M) 0.1-0.2 0.5 l-2 34

56.9 3.30 58.3 3.49 63.9 4,42 72.2 6.66 77.8 8.74 79.2 9.44 83.3 12.49

69.4 5.77 75.0 7.50 94.4 42.46 97*2 87.38

Distribution ratio

2.14 2.79 3.92 5.77 7.50

10.35

(6.$M) o-1-0.2 77.8 8.74

0.5 86.1 15.49 l-4 loo*0 a

(Si:M) 0.1 80.6 0.2 83.3 0.5 94.4 l-4 100.0

Tungsten(VI) = 430 pg in presence of 12M LiCl Mesityl oxide = 75 % in IBMK

10.35 12.49 42.46

a

with 75% mesityl oxide in IBMK and 0.5-4.OM hydrochloric acid. The results showed that for quantitative extraction of tungsten(X) at 1 M hydrochloric acid concentration it is necessary to use 12M lithium chloride as the salting-out agent.

Variation of shaking-time from 30 set to 3 min showed that a minimum of 2 min shaking is needed for complete extraction.

A number of representative ions were carried through the procedure and tested for interference. The tolerance limits (Table III) represent the weight ratios of ion to tungsten at which the error in tungsten determination is ~2%. Ions showing strong interference are copper, mercury, ruthenium, antimony, iridium, molybdate, selenite, tellurite and fluoride. The relative standard deviation (10 variates) was f1.2%. The extraction and determination take about 40 min.

Short communications 527

TABLE II.-Ern=acr OF SALTING-GUT AGENT

Salting-out Initial agent WCU, M Extraction, %

Distribution ratio

LiCl, 6M 0.5 31-9 1.17

: 444 34.7 1.32 1% 3 63.9 4.42 4 764 8.12

8M

IOM

12M

I+%% 1M

0.5-l

5 4

0.5 1 2 3-4

34.7 1.32 778 8.74 80-6 10.35 88.9 19.98

52-8 279 69.4 577 91.6 2747 944 42.46

@5 86.1 15.49 l-4 1000 cc

1 222 0.71 2 278 0.96 3 31-Q 1.17 4 38.9 1.59

2M 1 347 2 38.9

: 46.2 72.2

1.32 I.59 2.14 6.66

AK&, 1M 1 2

23+6 0.77 31.9 1.17 41‘7 1.78 61.1 3.92

NM 1 33.3 I.24 2 389 159 3 58.3 3.49 4 66.7 4%

Tungsten~I) = 430 pg Mesityl oxide = 75 % in IBMK

Dissolve a known weight (-0.5 g) of alloy steef in 9 ml of concentrated sulphuric acid and 50 ml of water. After the initiat reaction is over, heat the solution and oxidize it carefully with 10 ml of nitric acid and evaporate to fumes. F inally dilute it to 250 ml in a volumetric flask. Take a 2-ml aliquot of this solution in a separatory-funnel and add hydrochloric acid to give a concentration of 3&5&f. Shake with 10 ml of 100% mesityl oxide for 10 min to remove iron:% under these conditions tungsten(W) is not extracted. Evaporate the aqueous phase to about 5mf. Add hydrochloric acid and lithium chloride to make their concentrations 1 M and 12M respectively. solution for 2 min with 75 % mesityloxide in IBMK.

Shake the resulting Allow the layers to separate. Strip tungsten(V1)

from the organic phase as described above and determine it photometrically as the t&cyan&e complex, at 420 nm.

528 Short communications

TABLE III.-EFFECT OF DIVERSE IONS

Foreign ion Source

Tolerance Tolerance limit, ion/W, limit, ion/W,

w/w Foreign ion Source w/w

Pb*+ Tl+ cu*+ Hg*+ Cd*+ Bi*+ pt4+ Ru*+ Pd*+ Rh*+ Cr*+ Fe*+ Au*+ Be*+ Th4+ Zr4+ Ce*+ u*+ Zn*+ Mn*+ co*+ Ni*+

PbCI*.2H*O Tl*SO, CuSO,.SH,O HgCl*- - CdC1*.6H*O Bi(NO*)*.SH*O H*PtCl,~6H*O RuC1,~3H*O PdCl,.2H,O RhCi*.3H*O Cr*(Sb~)*~lIH*O FeC1..6H,O HAuCl,ti*O Be(NO*)* Th(N0&4H*O Zr(NO*), CeS(SOl)S

MnC1,.6H,O COC1*~6H*O NiSOI.7H*0

:.5 0 0 2.5 2.5 2.5 0 2.5 l-5

10 2.5 0.5

10 5 2.5 5 5 5 5 5 5

Cl*+ CaCl*.2H*O Sr*+ SrC1*.6H*O Baa+ BaCI*.2H*O Sb*+ SbCl*.3H*O OS*+ Na*OsO, Ir*+ IrCl. MO*+ (NH;)*Mo,O*~.~H*O CN- KCN s*o**- Na*S*O,.SH*O HPOI*- Na*I-IPOI.12H*0 vo*- NH,VO* Tartrate Tartaric acid Citrate Citric acid Oxalate H*C*O,.2H*O Ascorbate Ascorbic acid Malonate Malonic acid Acetate CH*COONH* EDTA EDTA SeO,*- Na*SeO* TeO**- Na*TeO, F- NaF so,*- Na*SO,,.lOH*O

2.5 5

10 0 0.5 0 0 0.5 5 2.5 1.5 2.5 2.5 0.5 2.5 0.5 5 2.5 0 0

305

Tungsten(V1) = 215 /.~g in the presence of 1M HCl and 12M LiCI. Mesityl oxide = 75 % in IBMK.

The results from the duplicate analysis of alloy steel No. 2735 (Bureau of Analysed Samples Ltd.) were 13.6 and 13.6% of tungsten (certificate value 13.65%).

Department of Chemistry V. M. SHINDE Indian Institute of Technology S. M. &XOPKAR

Bombay-76, India

Summary-A new and simple method has been developed for the rapid extraction of tungsten(V1) with mesityl oxide. Quantitative extraction occurs from solutions 1M in hydrochloric acid and 12M in lithium chloride (as the salting-out agent) with 75 % mesityl oxide in isobutyl methyl ketone. Tungsten is finally determined photo- metrically as the thiocyanate complex in the aqueous phase. Tungsten- (VI) can be extracted and determined satisfactorily in the presence of several elements. The method is shown to be applicable to an alloy steel.

Zusammenfassung-Eine neue und einfache Methode zur schnellen Extraktion von Wolfram mit Mesityloxid wurde entwickelt. Die Extraktion ist quantitativ aus Liisungen, die 1M Salzsaure und 12M Lithiumchlorid (als Aussalzmittel) enthalten, mit 75 “X Mesitvloxid in Isobutylmethylketon. Wolfram@%) wird zum Schlt& ‘m der &3rigen Phase als Rhodanidkomplex photometrisch bestimmt. Wolfram kann in Gegenwart mehrerer Elemente zufriedenstellend extrahiert und bestimmt werden. Es wird gezeigt, da13 sich das Verfahren auf einen legierten Stahl anwenden B&t.

RBsum&-On a &labor6 une methode nouvelle et simple pour l’extrac- tion rapide du tungstene(VI) avec l’oxyde de mesityle. L’extraction quantitative a lieu a partir de solutions 1M en acide chlohydrique et 12M en chlorure de lithium (comme agent de relargage) avec l’oxyde de m6sityle a 75% en m&hylisobutylc&one. On dose finalement le

529

tungstene photom&riquement sous forme de son complexe thio- cyanique dans la phase aqueuse. On peut extraire et determiner le tungstene(VI) de facon satisfaisante en la pr6sence de plusieurs elC- ments. On montre que la methode est applicable a un alliage d’acier.

REFERENCES

1. G Charlot, CoIorimetric Deterndnution OfElements, p 414. Elsevier, London, New York. 2. V. M. Shinde and S. M. Khopkar, unpublished results.

Taianta, 1969, VoI. 16, pp. 529 to 532. Pugsmon Press. Printed in Northern Ireland

GIass electrode measurements of sodium in albumin solutions*

(Received 8 July 1968. Accepted 5 October 1968)

SINCE the initial work of Eisenman, Rudin and Cosby’ on sodium-selective glass electrodes, several studies have been made comparing sodium-electrode and flame photometric determination of the the sodium content of various biological fluids. Friedman, Wong and Waftonp and Portnoy and Gurdjian,ss4 made their own small electrodes from Corning NASI1--I. glass; Moore and Wilson5 used two co~ercially available sodium electrodes. All investigators reported no indication of glass poisoning by any of the co~tituen~ in the samples they analysed.

The present work is limited to some observations on the behaviour of one commercialIy available sodium electrode in bovine albumin solutions during the course of a study to obtain supporting results for a mode! for ultrafdtration to be published separately. Since these eIectrodes are now manu- factured by several companies, they are readily available, and because of the expected increase in their use, it is hoped that these observations will be pertinent.

EXPERIMENTAL

A Beckman Research Model pR meter was used for the potential measurements. The sodium electrodes were the Corning NAS+,, glass membrane electrodes. The calomel electrode was the Beckman 5-in. fibre junction electrode. Sodium analyses were made with a lithium internal standard flame photometer ~strumentation Laboratory Inc., Model 143). Solutions were made up in de- mineralized water, with reagent grade chemicals. bumin lot 13.

The albumin was Pentex crysta~~i~d bovine ai- Agar-salt bridges were made by dissolving 2 % of Bactoagar (Difco Laboratories) in

the appropriate salt solutions. Polyethylene tubing 2.5 mm i.d. was used for the bridge. Special sample tubes were made by drawing the ends of 20-mm borosilicate glass test-tubes into rounded cones that closely fitted .the bulbs of the electrodes.

Two procedures were employed to determine the difference in sodium activity between an albumin solution and its ultrafiltrate. In the first the solutions were placed in separate containers electrically joined by means of a salt bridge. The potential difference between two sodium electrodes, one im- mersed in each solution, was then measured. The second procedure was to measure the potential difference between a single sodium electrode and a calomel electrode immersed in the same solution, and then to subtract the potential of the ultrafiltrate from that of the sac (albumin solution). For checking their responses, the two sodium electrodes were first immersed in the same sodium chloride solution and the potential difference noted. They were then checked for Nernst response by the first procedure with two known sodium chloride solutions (usually one 0.16 molal and the other O-08 molal made up to the same ionic strength with potassium nitrate). The potential was regarded as at equilibrium if it was unaffected by stirring the solution and it remained constant for 30 min. When the second procedure was used, the calomel electrode was connected by an agar-saturated potassium chloride bridge to the solution to be measured in order to prevent clogging of the fibre junction by protein; the criteria for equilibrium were the same as in the first procedure.

For determining sodium levels of unknown solutions a standard curve of potential us. log con- centration was constructed. The equation obtained for the curve was

E(mV) = 53.45 + 65.8 log C

where C is the modal concentration of sodium chloride in a solution of ionic strength 0.16.

* This work was supported in part by a USPHS Grant no. lT1 DE175 and in part by the United States Atomic Energy omission, Contract No. W-7401-Eng.~9 and has been assigned Report No. UR-49-932.