Determination of the alkaline earths in glass

VOL.

13 (1955)

ANALYTICA

CHIMICA

DETERMINATION

OF

ALKALINE

THE

ACTA

439

EARTHS

IN

GLASS

an ion-exchange mcthocl was described for the quantitative In a Ixevious palx+, separation of the alkaline earths from each other. This p;ll>er presents the application of the ion-exchange separation to the determination of the alkaline earths in glass. Preliminary cxpcriments indicated that most of the clcmcnts of glass appear with the calcium in the first fraction of the eluatc. For this reason, it was dccmcd advisable to isolate the alkaline-earth group before the application of the chromatographic separation. Furthermore, overloading of the column was avoided by the group separation.

An cxchangc column, a.54 srl.cm in cross-section area, was filled to 8 depth of 19 cm with colloidal aggregates of Dowcx-go, lot 50572, previously passed through a xzo-mesh SICVC.~Rcagcntgrade chemicals were used. A?l&3sis

of N.B.S.

sample

128

S;rmplc 128, a soda-lime glass, from the National Bureau of Standards was analyzed by the following procedure. A 1-g sample was decomposed by hydrofluoric and sulfuric acrds. After evaporation to fumes of sulfur trioxidc, the volume of sulfuric acid was adjusted to 5 ml, and 40 ml of Soy{‘, ethyl alcohol were added. The precipitate, which contains ail the alkaline earths and an appreciable amount of other cations, was filtered and washed thoroughly with SOO/~ alcohol containing xo”./ ,,, sulfuric acid. The bulk of the prcclpitatc was washed from the filter paper into a bcakcr. The pnpcr was ignited, and Its ash was acldcd to the precipitate. Then 7 g of ammonium iodide and 40 ml of concentrated hydrochloric acid were added to make the total volume about 150 ml. The nlixturc was bDlled nearly to dryness ; then it was cautiously heated to complctc dryness. The ammonium salts wcrc volatilincd on a hot plate. This treatment reduces the insoluble sulfates2 and converts them to soluble icdidcs. The rcsiduc was tl~ssolved in dilute hydrocirioric acid and trcntcd with brcmme. The insoluble hydroxiclcs wcrc precipitated twice with ammonia. The combined filtrates wcrc cvapuratcd to 40 ml, and pcllcts of sodium hydroxide were added to make the solution strongly basic. Then 3 g of sodium carbonate were added. The precipitate of alkaline-earth carbonatcswasflltcrctl, wnsl~d, and tiissolvcd in hydrochloric acxl. This solution was cvapornted to dryness, dissolved in 5 ml of wntcr, and trentcci as previously dcscribcd.1 Since no standard samples of glass containing all three alkaline earths were available, a synthetic sample was prepared by adding a small amount of strontivm to sample x28. This was nnaiyzcd by the same procedure.

It?cferoiccs

p.

.#4r

VOL.

13

(1955)

‘I’hc prcvcncc of lcad in this sample rcrluirctl a few alterations from the foreg.>ing procedure. Perchlorlc acid WIH substituted for sulfuric acid in the expulsion of fluoride. The rcsiduc was dissolved in tlilutc nitric acid, and a double precipitation with hytlrogcn yulfitlc was pcrformctl to rcmovc the lead. In one ciL4e, clcctroly+is at 1.5 amperes for jo minutes from a pcrchloric acid solution with n mercury cathoclc (Eschbach Dynacnth) WAY npplictl to rcm*,vc the lcatl In all other rcspccts s:~lnplc 89 wiL$ trcnted like 121).

‘I’hc results

of thcsc

analysts

arc

given

in Table

I.

group wcrc triccl and other ln-occdiircs for is&ding the irlkrlinc-cnrth after the removal of silicon from lxx~tusc of low results. For cxnmplc, Sill~l~)lC! 128 hy tWi~tlllcl~t wit11 lxxchloric and hyclrofluoric acids, boron was rcmovccl ‘I’llc iusolul>lc SUlfiLtCS, clcrivccl from the SO, by volc?tilizntion of methyl horxtc. prcscnt in the s~unplc, were dissolved by fusion with sodium carbonate and nddcd to the muin solution. Iron iUld aluminium wet-c lxccipitntcd twice with ammonia. ‘I’licn the- allcalinc cnrths wcrc lxccipitatcd by tlic addition of soclium hyclrosicle, sodium carbontltc and nlcohol. In the proccclllrc finally adopted, ammonium iotlidc and llydrochloric acid wcrc sulfates. licagcnt-grade usccl rather than hydrioclic acid2, to rcclucc the insoluble 11ydrioclic acid contains hy~)ophosphorous acid as ;L preservative ; this causes the the iron l)rccii+tation of the alkaline earths when ammonia is added to precipitate and uluminium. t\clclitionnl cl&nils of the work rcportcd in this lxlpcr may Ix found clsewhcrG. Suvcral cliscadccl

VOL.

13 (1955)

DETERMINATION

OF

THE

ALKALINE

EARTHS

IN

GLASS

441

Ia%a.~ME apr&s &liniinnt1on tic la s~licc, par pdcipi192sGKmcnts alcalino-tcrrcux peuvcnt Ctre s&par&. tatmn dcs sulfates cn solution alcoolique. 11s sont cnsude sbparb les uns clcs autres par Cd~angc cl’~onucl~rom~togmphiqiIc. Lxs rbsultats correspondent bien aux valcurs tlonndes par Ic ,,National Hurcnu of Standards”. %USI\~lXlI~NL’ASSC.~~(; Sach tier Vcrfldchtlgung tlcr I\‘lescls%urc. isolicrt man tlic Gruppc clcr alkallschcn 13rclcn rlurch Man rcduzicrt uncl lost dicsc Sulfate mit die Ausfdlung lhrcr Sulfate aus nlkohollschcr J.osung. JcJclwasscrstoffsilrlre. Ihc Trcnnung tlcr alkaliwzhcn Icrtlcn von cinandcr gclingt tlurcti :\u?rt~lu~ctictiromatoyraphic I>IC Analyst dcr Eichprobcn ircigt dass the .\lctliodc gcnau 1st. li151~1~I~I5SC15S l

,\I.

LERSER

=

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