ui :55! “l 1? IUMAN RUBID {ssjv :73: 71:95.7 l.».L.i).ih¢!-i§l|.'.tus ... 5‘.» 2:6 . 1., ...! 0%. A!!! Alilolfwli‘ ‘ ‘ .. K .....u11’i . ......n.n...rvl..x....a n J fling-v.8: 3.1.1151 .ll . 3:535:21: fl. 5 IS! A .1572; 513.. JHEbAL> II I k,_l LIH R .4 R Y Michigan ‘St'atc University THE SEPARATION AHD DETERMIIAEIOH OF RBBIDIEH AND CEEEUM BASED ON ION EHUBAHGE By Edgar'W. Alblngh A THESIS sublitted to the School of Graduate Studies oflflichigan State College of Agriculture and Applied Selence in partial fulfillment of the requirement. fbr the degree of DOCTOR 0F PHILOSORHY Department of Chemistry 195k /.— ML: ‘5'"? 53>- 753/ mmmm Appreciation is most “stormy omndod to Doctor flier Laminar undor who» kind and efficient supervision this sort rss affected. The author also Iii-hos to express his asti- tudo to Doctor Verne Stanza:- of tin Dow Chemical (to-pm for tho rubidium bromide oomatrm . mm mm W W H 'I‘ mar The conditions for the ion curiae-age separation of rubidium and calm have hm unwashed. in propel-eta." moodm for high parity" rubidiu- chhrido using an m We: “perm has been dowlopcd. It consists «station: of mm; m an quantities of col-stoic). rubidium chloride from a m musingnnsinbod 81cm. high“ 3.8 an. indicator“ m-Wsuh massaumoJ tarsal hydrochloric acid at nuance of LI: I1. per sink. The rowan chiorido is recovered from m pm? win. of duh by evaporation and pmipiution with Wm chloride. Plano- photuotrio analysis of the purified product own the rabidiu chloriao content to be approflnately 99.7 pox- com. Gain chloMQ was prepared in ponucitc by treating the moral vi» a m or macaw and sulfuric acids and than recrystallising the resulting ccsim elm. The sodium and potassium content wars to rennin constant after several rocryctcllizstions. For final purification the «aim aim was converted to the iododichloridc and mcmtaniud. Tho purified product was analysed flmcphotomctricclly and the easim chloride content is approximately 99.7 per cent. Hmphotonstric determination of rubiditm and cesium is described. The flu intensities at 780 and 852 mu were measurcd for the ostination 01‘ rubidiu and coaim reapoctivoly. The enhancement effect. of large amounts of rubidium on othor alkalies is demonstrated and method! proposed for their sppromation in the purified rubidium chloride. A wished for the quantitative determination of midi“ end oeeim beset! en ion exchange has been developed . The procedure involves separating empties of the nixed chlorides by elution rm a calm. coc- uinia. ereeinbedol Done:5°,nimshmleeh, 87 a. hithzj u. is lineter sith 0.1 and Woman acid et a new veto of 2.7 .1. per III“. After elation the ass-propane functions of diluent are ”meted to dine" end the alkali ate]. content deter-iced by weighing the int!“ Pundit. and «sin sultan. 1: null bleak correction, chained by evaporating portin- ef elite“ and reigning the ignited “Meta We, wee tea mommy. u may of one per cent wee «mm for M 3;. sqlee of the chlorides then mbidim end casim are present in Wotan equal proportion . TABLE OF cmnrrs Page Email-... 5 mmu.....n.............................................. co Conditions for the Ion Exchange Separation of Rubidiun ad c.“ml000000000000000...OOQOOOQ0.00.0........OOOCOOOOOOOOOO.I (”mice or R'smeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee Preparation of Ruin for Un............................... Filling the calmeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeoeeeeeeeee ammo or AcidOCOOOOOOOOIQQOOOC0000.00.00.00.00.000.000.00. Construction of Column and Pressure System................. hmng the columOOOOOO0......0.00......OOOOOOOOOOOOOOOOOO Ion Exchange Separation of Rubidium and Cesium................ Preparation of Rubidiun Chloride by Ion Exehange.............. Preparation of Cesium Chloride from Pollucite................. Mphotonotry 0t Rubidim ..nd ceaimeeeeeeeeeeeeeee‘eeeeeeeee i; The Qeentitetive Determination of Rubidimn end 0081113...ouo¢o - mxoeooseeoeeeoesssOeeOeeeeeeeeeeeeeeeeeeeeoeseeeeseeeeee00.. Sh mmm 0mm.eeeeeeseeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeoseeeee 56 MN «on 5515113 Se coco IHROWCIIOU MENTION In the deteminsticn or the elkslies e seperetion is frequently nsde which divides the tail: into tee groups. One group consists of lithiu and sodium; the other , potsseim , rubidiun end oesius. This eepcetien is eeecepliehed by the use or either the ohleropletinete or perehlorste nethed , both of which relieve the potessius , rubidiu end cesius lowing the lithim end sodium in solution (19). no: certain mentions , the chloropletinete nethod reportedly acres quantitative ssperetion (20,28) . n: the perchlorate method, the nine chlorides o: the slkeliee ere converted to the perchlorates end then sodiun end lithium ere extrscted sith e mixture of submit-one n-butyl elcohol end anhydrous ethyl ecetete . mus-cue sepsrstion is obteinsd (21) ., There ere several methods available for the separation end data-sin- etion of potusitu , rubidium end cesim. Although these methods ere seneshet empiriesl, under limited oonditions they ave good results (19) . In one method for the separation of potassium freon rubidiu- end cesim, 9-yhosphe-clybdic ecid some to precipitate rubidiu- snd cesin while pet-seine remains in solution. Although cone poteseiuu is co- precipitated O'Leery end Pepieh (28) ropert good results to:- certtin concentration rsnges or potsssiue , rubidium and ceeim. Before rubidium end oesiun can be sepereted , the phosphcnohbdste precipitete lest be dissolved in sodium hydroxide , the nolybdsnm removed with hydrogen eultide end the elkeliee converted to chlorides after e chlorOpletinete separation . The eeperetion of rubidium tron ceeiue cen he brought ehout by pro- oipitatinz oeeim tron the mind chloridee Iith eilico-tungetic eoid . Ruhidiun ie determined in the riltrete es the perchlorate or chloro- ’ platinete . ‘i‘o deternine ceeion , the oilioo—tungetic ecid precipitate in die- eolwd in eodim hydroxide, neouroue nitrete edded to more the silico- tungetete end cesium 1e deter-ined ee the chloropletinete or perchlorete utter oxidation of the emcee mercury {19) . Another method for the eeperetion of oeeiun frm rubidiu involvee the torn etion of e precipitate with ferric chloride and anthem chloride thioh remorse ceeiun. Ceeiun is determined as the chloropletinete or perchlorate efter the precipitate is dieeolved end the iron and antimony moved (12). Wells end W (h?) report It method for the eeperetion of potueiun , rubidium and cesium An extreotion of the nixed ohloridee rith ebeolute alcohol , which ha been eetnrated with Ivarogen chloride gee , eerveo to remove rubidium and ceeim from peteeeim. 'iu'he eepu-etion or oeeim from rubidiun depends upon the yeeter eolubility in alcohol or oeeim eultete. “this method is quite enpiricel end the condition, ee well no the nuher or extrectione , ere dependent upon the amt of petunia: , rubidim and onion present. More recently Soto ( 37) described e method for the determination of the alkali netele bleed on the difference in the eolubilitiee of the henyl dipiorylenine eelte in mind orgenic eolvente . An accuracy of five percent wee reported. Another nethod for the eeperetion md determination of rubidium and eeeiun beeed on the fez—notion of the elkeli polyhelidee ie siren by Inner: (ht) . In this lethod, the triniodidee ere toned end upon treeteent with oerbon tetrachloride only the rubidium eelt deconpoeee . A nethod for the onentitetive determination of ceeiun end ite eeperetion tron wbidiue end poteeeiun has been propoeed by Dutt (ll) . In thin method ceeiun is precipitated ee c..nm(no.). and determined either by weighing the precipitete, CeJeI-e(l0.)., or by titrating the nitrite content with ceric enlfete . Both the grevieetric end volmtric procedures here been adopted to the nicrodeterlinetion of cerium. Several workers have need spectrog-ephic end Ilenephotonotric pro- eednree but theee in generel ere limited to email eeounte end ere nore treqnently need for auditetive identification rather then quantitetive deterninetion (S,6,1o,13,15,h1,h5) . thexrnethode diecueeed here are representative procedures and may lore ere found in the literature. Freeeniue end Jender (125 here reviewed the nethede through 19110 and e diecueeion of cone of the methods is given by moor-end (19). There eppeere to be no truly specific reagent for either rubidium or ceeiun ione (19). The chemical methods of determining rubidium end ceeiun ere either rather long and involve e number of operetione , or the eeperetione ere inconplete, giving rise to errors ee large on five percent. In the hope of finding e nethod which would give eoctu-ete reeulte but eleo heve e need-m or einplieity, it leaned edvieeble to try mother eppreech. Rienen end co-morkere (7 ,39) developed en ion er- chenge method for eedim end poteeeiun thet gives excellent reeulte but doee not involve the tedieue proceduree of the chemicel nethode . A review of the literature indioeted thet the ion euhenge eepere. tion of rubidium end ceeiwn hed been eecmpliehed by Ieyee (23). lo quentitetire reeulte were given for rubidime end oeeim but 99 percent recovery in cleined tor eodiun. It .eeened thet for en ion eachenge method to be eucceeetul , it ehould be cepeble of reeolving neero quentitiee while giving edequete intervele of eeperetion between the Iverioue ione end yet not involve mlinited voltmee or eluent. It I»: toverd this end that the following work wee directed. HISTCBICAL HISTORICAL One of the first attempts to separate the alkali metals employing the ion-emhenge technique wee carried out by Cohn and Kuhn (9). A colunn containing e reein bed 1.0 so. on. in eree end 10.1; on. high of oolloidel egglmeratoe of Dove: 50 and a recording counter to any the relative activity in the effluent eolution we: employed . A neutron activated mixture containing 1.0 mg. of eodim, 10 mg. of poteeeiun, 8 ng. of rubidium end 13 mg. of cesium wee dieeolved in water end eb- eorbed on the reein. Elution use then begun with 0.15 noreel Indra- chloric ecid at e flow rate of 0.3 ml. per minute end completed with 0.3 normal hydrochloric acid . The effluent from the colunn we collected in e number of frectione, each of which wee radiometricelly' enelyzed for In“, K“, Rb” end Col". Sodium was recovered in one fraction which eleo contained one per cent of the cesium. The remainder of the eaple wee recovered in the other fractions with incoxnplete separation. The tote]. elution required 160 ml. The firet fairly complete separation of sodium, potueiua; , rubidium end oeeiun by ion exchange was accomplished by Royce (23) . A glue onion 1 on. in diameter and 50 cm. high, fitted at the lower end Iith e eintered glue disc, as filled to e height of no on. with Albernte IR 100 reein heving e neeh eize of 80-12C. The unplee con-inted or nixturee of in“, x“, no” and eel“. The separation use renewed with e epecielly eenetructed Geiger tube which indiceted the movement of the imdovnthecoluen. Anothertebeveeplecedeeeetoneeeuretb eetivity c: the eluete eel it peeeed tron the celuln. Ithe eeperetion ebtedned, ee reed tree the elution ewe. ie wee-Mendy 25 ml. betwen Iodine: end poteuiu, 15 Ill. beteeen poteeeitu em rubiditl m 10 ll. betmen rubidim em «sin for e eixture eonteining 15.3 as. eedim, 21M) ng. poteeeiun, 28.3 ng. rubidium and 25.5 ng. of ceeim. The initial elution nee cerried out with 0.15 normal hydrochloric eoid but efter the lent o: the poteeeiun wee removed the acid etrength wee inoreeeed to 0.3 nomel. The complete elution required approxieetely 825 :1. or chart. lo quantitative date in gm for rubidium end ceeim but ee en emple or the roeulte obteineble w evelueticn of the mo under the elution me 99 percent recovery on claimed for eoiiue . _ A method for the Beeperetion end deterninetion of eodim end potueiun employing an ion-exchange eeperetion ha been propoeed by linen (7-) . The nethod coneiete of two ctepe: e eeperetion or the ecdim em poteeeim by name of elution through a cation exchanger , end e titration of the chloride in the alkali chloride reeiduee obteined from the evepcr- etion of the eeperete frectione of eluete to dry-non . For the ionuemhenge separation e column 3.80 cc. cn. (2.2m. in die-eter) by 59.0 on. containing 59.5 g. of colloidel Donne: so reein nee employed. Snplee c‘onteining up to 500 ng. of the nixed chloridee eere eepereted by elution with 0.7 normel hydrochloric ecid et e nor reto of 0.60 nl./nin./eq. m. from this column. In thie elution the tiret 370 ml. of eluete vere diocerded. The next 160 ml. conteined the Indian end the following 190 :1. contained the petulim. The eveporetiene were oerrled out on e eteea bath end the reeiduee heated in an oven to 1h0°c . The residual hydrogen chloride wee deter-I- lined by titration with «men-e beee end the chloride content by the Kohr titretion. The elkeli chloride content we: then celouleted fro- the difference in these two titratione . Excellent reeulte ere reported. EXPERIMENTAL mmmmrm. Conditions for the Ion Exchange Separetion of Rubiditm end Ceeim ' The theory of the ion exchange proceee has been extensively investi- gated end lunch or the work is emu-1nd by Kunin and Myers (25) end Bel-celeon (32) . In practice , however , the final experimentel conditions for at given eeperetion ere neinly found by trial end error methods . From experience it he: been learned thet certain factor: greetly influence separation. The meet important or, theee ere: l. leture of the main 2. Sample-resin ratio 3. Concentration end nature of eluent 14. Flow rate 5 . Exchange affinity of the ions involved 6. Shape of column 7 . Temperature ghoice of Benin Two different resins have been employed in the separation of the alkaliee . Kaye: (23) used Amberlite moo which is e phenolic methylene We acid type. Cohn and Kohn (9) end Rieman (7 .39) need Done: 50 which is e nucleer eulfonic acid exchanger. Dower 50 appeared to have two eduntegee over Alberlite 11-1100. In generel the nuclear eulfonic acid type in leee subject to attack by acid end having e greater eepecity per area (25) should y." better resolution per unit volume of reein bed. tor theee reuone Done: 50 was chosen. Dene: 50 is produced by the polynorisetion of styrene with divimrl- bmene, tolleeed by snltonstion. The percentage of diviwlbensene detereinee the degree of cross linkege end consequently the density. It hes been shown thet the degree of eroselinkege influences selectivity (26) end on. dog-u a: swelling or the resin (33) . Insufficient an ere usilsble te deter-ice the per cent creeelinkege et which senile- selectivity for the elkelies exists but it ha been found thst ti. 0 tselve per cent divinylbemene resin is eetisteotory. This eroeslinkege , senile- for the Dove: series, else gives s sexier“ cepeoity per gre- em shinin- of swelling sithin the Boss: 50 series. In the choice of resin one further fector needed to be considered, the site of the resin perticles. The smaller the particle sise the greeter the resolution (36). At extremely smell pertiele eises the resistence of the oolmn to sheet new becones eppreeieble . Per e colun conteining e resin bed 15 on. high and 24.2 on. in diueter of colloidal Dose: 50 e flow rate or 1.? ml. per minute required s pressure of over 20 inches of mercury. . The resin finally chosen res Done: 50 , 12% divinylbensene croulinka sge Iith e particle size of zoo-too mesh for the preperstive calm end s perticle size of nines boo nesh for the enelyticel colunn. may»: of Resin for Use the emeroiel grade of Done: 50 as received from the neneteotnrer requires rether extensive preperetion before it is suitable for use . The first step in the preperetion involves the removing or the so-eelled 10 'fines' (7) . The "fines“ are extremely sIell particles of resin that have been produced during synthesis and subsequent handling. If these saell particles are not moved they sill aigate through the 001m and eventually obstruct the porous ddcc'in the better. To remove these particles the crude resin is aimed with ehout three tines its value of water , the resin permitted to settle , and the supematant liquid decanted. This process is repeated until the solution above the resin is clear after a few minutes of settling. This process nay consuls more than 25 per cent of the resin. In one attupt to use a batch of colloidal Dose: 50 that had been insufficiently washed , the fine particles diffused through six feet of Tyson tubing into the reservoir containing the eluent. The move}. of iron frm the crude resin is also important. Samuelson (35) race-sends treatment with five normal hydrochloric acid. Goudie and Riuan (18) recommend the passage of dimeniun citrate through the resin. The procedure follosed was a combination of these in which the resin was given several treebnents in a beaker with five normal hydro- chloric acid, and than, site:- being washed with distilled water and ‘ placed in the cclmn , one molar dimoniun citrate passed through the colun until the remaining iron was moved. Filling the 001m The filling of the calm is very important 3 if not done properly channeling will occur and instead of receiving full efficiency from the colmen the elnent only comes in contact with part of the resin. The first aethed attespted was that of pouring the dry resin into the «lac. After setting, the resin swelled leaving channels.. The seat satisfactory sethod appears to be that of first filling the colusn with ester and then slurrying in lean portions of resin through a tunnel that dips belov the ester level in the coan (29) . As the resin-water slurry enters the column the particles gradually settle giving a unifom bed. A large beaker is placed under the calm to catch the displaced water and resin that overflows. The slurry should be added at such a rate that the extremely fine particles do not have a chance to settle but are carried over the top of the colt-n. If the rate of addition of resin-water slurry is too slow bands of fine particles will develop shich nay migrate through the eclusn and obstruct the porous disc . A properly filled column has a. unifors color and exhibits no chemling. Choice of Acid When a solution of a salt is placed on an ion exchange resin, such as Dove: 50, the cation exchanges with the hydrogen ion of the sulfonic acid groups in the resin. This nay be pictured as a reversible reaction where R“ represents the sulfonic acid pump of the resin. RH +va";—fasa +H+ That this is an equilibrim process has been demonstrated, the final equilibrium being dependent upon the concentrations of the two cations and the relative cation-resin bond strength (he) . Thesshaneaeluucneestsisingssimeefthsslkalisaisplaeed esthsssidfmoftheeelun,wdrogsnionsarereplacedsineethe affiutyefthaslhslieefortbresinismaterthenthetefwdregsn ism. 1When elation begins the rate of litigation of the variem alkalies adlldepecdwenthsirrelative affinities forthminandthewdre- n ion coneeatrstdcn of the donut. The relative order of affinities ofthe alkaliesforthesulfenieacidtypaeachanuersareca>lb>x>la and consequently their order of eluticsi will he He, :, n and Ge (22,23, ha) . it was found in ionnexohsnge studies with the rare earths that the equilibrim existing in c colmn could be shifted by the use of ca- plexing agents slush varied the effective menu-«ion of the metal V isns ml enhanced separation. It was thought that the diner-amen in ammo: existing between oertsincupsuade inths alkalinetal fauilysqenertaninflunoespsa their separation in a mar similar to that exhibited by the differences in the stability of the rare sartkpcitric acid complexes. Hydrochloric (7) and perchloric acids (22) both have been used for the separation of sedim and pcteeaius but due to the different aspen- aentel conditions involved so capariscn betasen the degree of separation obtained was possible. It sea felt that if an anion effect is ispertant a comparison of the elution of seals. and potassium with Weehlsrie and puchleris acids should desenstrate it since a trusty fold difference exists houses the solar solubilities of the sodiu- snd potassiu chlorides and psrchlorates (38). 13 To detox-sine if an anion effect exists two runs were node, idem- cal, except in one case elution was carried out with perohlerie said and in the other wdroehlorio acid . The calm oontained a resin bed 31 m . high and 2.2 on. in dianeter of zoo-mo nesh Dow: 50. Twentyefive nilligrae staples of Hellinckrodt reagent grade sodimn chloride and Baker Analyzed Reagent potassium chloride were taken and eluted at s flos rate of 3 .1. per minute with 0.75 normal ivdroohlorio said in one run and 0.75 normal perchloric acid in the other. The elution was followed flmophotmetrioally. The results are shown in Teble I . TABLE I _ SEPAMIW OF SODIUM AID POTASW WITH HEROCHLOHIC ADD PMCHLORIC ACIDS _,.r Volume Containing Volume Representing Volume Containing Acid Sodium (1111.) Separation (ml) Potassium greetion ll. H01 use-580 I 15 580-1130 1’ 15 nae-lino I 15 mo. uao-sao I 15 580-860 : 15 ado-.1030 : 1s Evidently the replacing of chloride ion with perchlorate ion has little influence upon the elution of sodiun from the column , hovever , the internal of separation between sodium and potassium has been reduced by 270 I1. or nearly one-half the original separation. The value of eluete containing potassium hes been reduced from 290 ‘1. to 170 :1. These data indicate that the more insoluble the salt formed between the cetion on the column and the onion in the eluaht the more easily that onion is. removed tr. the oolusn. As for the magnitude 0! this effect it esn only be ssid thst s large difference in solubility seems necessary for any appreciable influence upon separation. Undoubtedly the sbsolute solubilities ss well as the differsm in solubilities is s factor. A review of the solubilities of the chlorides or sodium, potusim , rubidium and cesium reveals that the chlorides are s11 quite soluble (Table II). TABLE II sownnnms or mu cmmss (Holes For 100 arm Water st. 25%) (38) Alklli Chloride Solubility Heel 0 .615 [C1 o.h76 RbCl 0.730 0361 1.130 Potassium chloride is the least soluble (on a molar basis) while rubidium! chloride is intermediate between potassium and cesium chlorides; cesium chloride is the nest soluble . Thus , it there is an anion effect at this level or solubility it should enhance separation. The peru- ohlorstes ot potsssim , rubidim and cesium all have low solubilities with: e slight decrease from potassium to cesium. It was felt that this 15 let solubility in addition to the slight difference in scluhilitiee gave perchloric no advantage over hydrochloric acid. Since the elutions were to he followed flanephotcsetric ally lmiro- chloric acid offered the further advantage that the chlorides of the alkali metals are the nest sensitive for Ilene analysis . be. these considerations hydrochloric acid was chosen as the elusnt . Constructgn of Colgg m Pressure Men Figure 1 shows s typical colmn and the pressure systes used to deliver eluant (29). Pressure is supplied by tank oxygen. Two regu- lstcrs are included to control the system pressure end consequently the flow rate. me is a diaphragm type on the cavgen tank. The other (3) consists of a length of 6 In. glass tubing dipping into a column of W whose height is determined by positioning the leveling bulb (c) . An exit tube is provided to carry the excess own and mercury tunes from the regulator into s container or six normal nitric acid (A) which is fitted with an exit tube containing sscerite. The Isrcury nsnoneter (D) permits reading of the system pressure. This is convenient for reproducing flow rates and clicking the condition of the system at various tines. A 12 liter reservoir is included at (E) to malaise pressure flus- tuetion and help nintsin a constant flow rate as the volume of elusnt in bottle (1’) decreases . (2—‘1 a VIII/IIIIIIIIIIIIIIIIIIII I ZMhm>m memmmmn— 024 223400 wozI Adzmoz mm._ It; .23.me 024 23.9m3m no 20:.qu N mmDGE mKMFS 2. 52:40) w.. c1. N._ 0.. 0.0 me .0 vio ‘ Nd _ mm ll on ow. O¢N own 'W'd'd 19 to 1000 I1. and cesiun in the fractions from 660 to 1180 :1. with m overlap in fractions from 660 to 1000 ml. The variables that could be changed without resorting to a different resin bed were the sample sise, acid concentration and flow rate. Another run was carried out using the sexes resin bed but the sesple siee decreased to 0.05 g. of midius chloride and 0.07 g. of cesiun chloride with 1.03 normal hydrochloric acid used for elution. Fractions of 26 e1. were collected and analysed as in the previous run. As seen from Figure 3 rubidium appears in the fractions from 930 to 1M0 n1. , cesium in the fractions fros 1185 to 1600 all. with both being present from 1185 to who .1. In couparieon with the previous run'it can be seen that complete elution required a larger volume in Figure 3 and that separation is somewhat improved as Judged by the difference in overlap areas in Figures 2 and 3. It appeared from the comparison of figures 2 and 3 that a closer approach to equilibrium conditions would be necessary before complete separation would be possible. In the next run easples containing 0.05 g. of rubidim chloride and 0.05 g. of cesium chloride were eluted fro: tin sane oolusn with 0.38 annual thrdrcchloric acid at a flow rate of 1.5 ul. per minute. Figure I; shows the results. Bubidius appears in the fractions fro- 3250 to 1020 ml. and canine in the fractions from 13300 I1. on with only a 20 n1. portion containing both alkalies. free these results it became evident that if macro suples were to be successfully separated greater resolution would be necessary. It did not seen feasible to further reduce the acid strength of the eluant since the volumes containing the alkalies was already appreciable. .222 mum .....2 n._ “uhdm 30..“— Om x9500 4490.....Oom0 mwhwc‘da z. .20 N.N 024 I9: .20 mo "0mm.z_mmm mgr—04:0 2:.mwo .....O .0 No.0 024 onOJIo 23.052“. ...0 .0 00.0 “wqmc‘dm 0—06. o_mo..IoOmo>I 442moz no; It; Zammo oz< ZD_o_mDm no 207—.34m m mane; mmwkj Z. w2340> _.N m. .5 m... 3 __ m .o e .o _ _ i Z _ a _ _ _ a o In mm l. 1.. Joe I. lJow. OdN own .2272 .3322 J22. um .wkdm 30-2.”— Om xu>>00 44054.50 ..20 70um22420 22 .20 N.N 024 212022 .20 md “cum 220mm onOJIO Samwo “20 .0 00.0 024 00220-210 232020322 .20 .0 00.0 0.72240 0204 0E04100m0>1 445502 000 I223 $5500 024 22202mzm .20 20.2.3.6 4 $23072 mmmtn z. u2340> we ed we oe m.» on - en Wm l 2 IF 2 2& _o l. mo mm ..L .l 1.23 TI II I: IJHOA: .l. lemoem “ 2 2 2 2 2 2 2 2 2 22 -- 2 2 2 Se 20 Increasing the height of the resin using colloidal Dowex 50 was pro- hibited by the increased pressure that would be necessary to obtain a feasible flow rate. Amthsr column containing a resin bed of 2004400 meh Bowen 50, 68 cm. high md 3.8 on. in diameter, was prepared. After placing a mixture of 0.056 g. of sodius chloride, 0.083 g. of potassium chloride 0.056 g. rubidiu chloride and 0.08131 g. of cesimu chloride on the column elution with 0.70 normal Ivdrochlorie acid was begun at a flow rate of 1.8 ml. per nimte. Fractions of 15 ml. were collected, evaporated to dryness, diluted to 100 ml. in rclmnetric flasks and analysed fluephotonetrieally. The results are given in Table III. The separation between sodim and potassim is nearly 8000 al., between potassium and rubidium, nearly 2600 all. and between rubidiue and cesimn approximately 2700 n1. 0&1! enough of the ceeim was eluted to deternim its position in the elution sequence . TABLE III narrow or 0.056 a. scam CHLORIDE 0.083 a. museum ammo, 0.056 c. momma CHLORIDE, 0.0813 a. come cmme me 0.70 some mammals ACID WITH A FLOW RATE or 1.8 ML. rm mu Resin Bed a 68 on. high x 3.8 on. in dinneter 200.1400 mesh Dower. 50 ~w— Velma in H1 . Volume in K1 . Volume in H1 . Veins in Containing Sodius Containing Potaseim Containing Rubidiun H1. Contain- - W hose-51:30 13h10~16110 , 18710-41360 21.060- VVV—v' 21 A series of run was condmted with the pun-pen of obtaining con- ditions that would provide separation of rubidium and oesius chlorides on a preparative scale. In the first of this series a 2.08 g. sample of a chloride sisters containing approxisately 70 per cent cesium chloride and 30 per cent rubidium chloride with small amounts of sodium and potassium chlorides was placed on the colum described in table 111.— This mixture was prepared from a rubidium bromide concentrate supplied by Dr . Y . Stsnger of the Dow Chemical Company, Midland, Kichigan and is referred to as the Dow mixture . Elution was carried out with l .0 normal hydrochloric acid at a flow rate or 14.1; 31. per minute. Figure 5 gives the results. lthese conditions give sons separation but the greater part of the rubidius fractions contain cesim. [eyes (23) in his separation of the alkali metals carried but the initial eluticn through soditm and potassium with 0.1 normal W- shloric acid and then completed elution with 0.3 mal. As shown in Figure 1;, 0.3 normal Ivdrochlorio acid removes cesiun very slowly from a cclunn of Bowen 50. Although it affects a near separation, the value of eluate in which rubidium or cesium appears is too large to make the use of 0.3 nornel hydrochloric acid practical. However, from Figure 3 it can be seen that 1.0 normal lurdrochloric acid satisfactorily removes rubidim and cesiun from a column of Dower 50 but the separation is inc-plate. It was thought, following the approach of [eyes (23), that perhaps an initial elution with 0.5 normal hydrochloric acid followed by an slution with 1.0 normal hydrochloric acid would give an adequate 2:2 mud .Z. co mkqm Sat... 0.04 0E04I00mo>x 43,502 0. 0.243.; on xmzoo Imuz 00¢-OON do 19.9245 2. .20 mh 024 10.1 ..20 00 5mm Emum wants—2. Zoo in. .0 mo.N ”whims—4m 22mmo oz< 23_Q_m:m no 20:.qu m 550.... mmwt4 z. m2340> om. «.2 . mm ll- 3w. om N e M i 0 _ _ _ _ _ n u o ..I. «loo m. o 0 rl .... .L .x mm Flu .... low M \_ w r K | TI ...1 om. _ - _ _ _ _ 4. m. om. 22 separation with the respective alkalies appearing in volumes that would be practical. A staple containing 2.19 g. or the Dow mixture was placed on t1! sue cclm as in Table III and with a flow rate of h.h I1. per mm- 19 1. of 0.5 normal wdroohlorio acid were passed through the colm. Io rubidium or cesiua appeared in the effluent . nation was completed with 1.0 normal hydrochloric acid. Figure 6 shows that the separation or. rubidim and oesim is not improved. ‘ Another run was carried out with the same calm, identical flow ' rate and a 2.11 1; sample of the Box mixture, but the elusnt changed to 0.7 normal hydrochloric acid. Figure 7 represents the sepu'ation obtained. Although considerable cross contamination exists a poster percentage of the eluate containing rubidium is free iron cesium tron figures 5, 6 and 7 it appeared that a more favorable sqleo resin ratio would be necessary if a satisfactory separation were to be attained. figure 8 shows the results of using the conditions aria Figure 7 but decreasing the smile size to 1.05 g. The separation is couplets emept for a small mount of tailing of rubidim into the cesium fractions. To further increase separation the height of the resin bed in the colum was increased to 81 on. A 1.02 g. sample was taken ad elutioa carried out as in Figure 8. Caplets separation was obtained as is evident tron rum-a 9. Rubidiun is separated from cesim by a value of over 600 all. 2:2 ii £2 «.0 NEE 2,0,; 0.04 0.547.080»: .2502 0.. ... 3-0. .2502 0.0 ... 0.0.0 #2430 On xmgoo Imwz 00¢..OON no mm...m2<.o z. .20 m.n 024 I9: .20 mm ”mum Emma mmahxzz 300 m0 .0 m_.N 0.5523 7 23_mm0 024 23_o_m3m m0 20:.DJm w mmzol _ mmu».n z. mznno> 0.8 ~00 - :0 0.00 00. 0.0. , N0. 3.. on mm 'W'd'd .ll.ON_ ______________8_ .222 mm; {.2 «.4 ...:4m 304... 0.04 OEOJIOOmorz ...42moz Nd #24340 On xmBOO Imus. OOV-OON no. mm»m24.0 z_ .20 0.0 024 10.1 .20 00 “000 Emma mekxE‘ 300 do .0 :N @40240 2D_mm0 024 23.0.03m 00 202.340 N. mmaoi - mmmP: 2. 92340) N0. of , 0.0. 0.9 on. , Ne. . on. 0.3 _ - fl _ _ _ 0 _ _ _ _ i 0 I am. .10... In low w I. m0 I. II low. ..I 11 IL _ _ _ _ _ _ _ 0 _ _ _ _ _ 8. eh;‘ mm; .Ji w.q “mp4; .50.; 0.04 0534100m0>T ...4Emfz .....n. .....2430m Om xw>>00 Imus. 00¢..OON do «3.00.0245 z_ .20 0.0 024 10.: .20 00 0mm 2.0wm 0&9522 300 no .0 no. 041240 23—mm0 024 2205.-.”. m0. 20:.qu m H.530; .wmeJ Z_ .....23...3> v.0. - we. 00. 0.0. , 0.9 0.3 , 0...... 0.0. 0 0 _ _ o 1 \ mm .Jco ..d 1,006 .w ION— lul IL ____L_____ _8_ .3... my”... .-.... 0.14.. ..r41 05%;... 0.04 O_mO.._IOOm0>I 44.2«02 5.0 ....Z4DJN On xwioo Iwm2 00¢..OON no mm#m24.0 z_ .20 0.». 024 121.20 .0 .000 Emma .mmahx_2 300 do .0 NO; .m4024m 23.0m0 024 2D_0_mDm “.0 20:94.0 0 major. mam... _ .0 Z. wZ.......o> 0.NN m..N 0.3... N.CN 4.0. 0.0. 0.... 0...; _ _ n _ . . . . TI [or .I. m0 l1 ..0 00...... .I. 1100. _ _ _ _ 0. _ _ . b . _ _ 0 _ 02 23 PREARMIH a 3m OWE I! IN munch". The principal impurities in conercial rubidiul chloride are potassium and cesium with a somewhat ssaller ascent of sodiu. lubidiua coupounds are intermediate in solubility between potassiun and «sin so that any classical scheae for purification must include at least two series of recrystallisation. Archibald (l) reccuends recrystalliaing the icdodichlorides for reaoval or sodiua and potassiua, and crystallis- ing tb tsrtrates to remove cesium. i‘o reaove the nounts of impurities present in conercial rubidium chloride an ion exchange nethcd offered the possibility of being more efficient for snall quantities . To acconplism this it would only be necessary to elute a seaple from the proper coins and recover the purified rubidium chloride iron the appropriate fractions . It has been shown (page 18) that a one arm s-ple of the Dow Ii:- ture could be completely separated with a column containing a resin bed 81 on. high am 3.8 on. in diameter of 200-1400 mesh Dower 50 by eluting with 0.7 normal hydrochloric acid at a flow rate of h.h :1. per ninete. A run was made using these conditions but the sample of Dow sitters us replaced by a 1.0 3. sample of comerciel rubidium chloride (the Fisher 3cienti£io Gaspamr) . Rubidiun appeared in the eluate fractions tro- l6.3 liters to 22.2 liters. Potassium was not detected in the 600 ll. of eluste preceding the rubidiua fractions nor was cosine round in the 1:00 ll. of eluate inodietoly following the rubidium fractions. 2h hr recovery of the purified rubidim chloride the fractions fro- 16.2 liters through 22.! liters were ocnbinsd in floor beahrs protested by Pyrex cover glasses which were supported on Pyrex healer backs. the seabinsd fractions were «ape-ma on a hot plate at 120% which was surrounded by a protective netting of cheese cloth. It is desirable to use an evaporating tomsrature below that at which the resincdeconpoees since on decomposition the resin would introduce sulfate ions into the purified asterial. the final colbinsd residues contain“ censidsrdale amounts of resin and sons silica, as well as the rubidius chloride. To remove the silica the Mined residues were dissolved in a minim mount of distilled water and filtered. For resovsl of the resin rubidiun was precipitated as the chloride. This was accosplished by asking the nominee! filtrate and waemiigs fro- ths silica removal 6 normal with respect to hydrochloric said, evaporat- ing until Just before crystallisation began md tun passing in Wm chloride. I !b hydrogen chloride was supplied by a generator consisting of a suction flask, a separatory fmnel and an exit tube. Concentrated sulfuric acid was placed in the suction flask and then the separatory funnel, which was held in place by a rubber stopper, inserted so that the tip of the stmgwas below the surface of tb salu- furio acid. the separatcry funnel was filled with concentrated Murc- chloric acid and then as the hydrogen chloride was needed the wdro- ohlcric acid was added by positioning the stopcock. 25 the solution containing the purified rubidiu- shlcride was cooled with u ice bath and hydrogen chloria passed though the solution until no hn-ther precipitation occurred. The supernatant liquid was decanted and the precipitated rubidium chloride washed three tines with anhydrous etlnvl alcohol. A second crop of crystals. was obtained tron the decanted nether liquor m washings. The rubiuun chloride was dried in an oven at 120%, tree-toned to a mum. furnace, end meted to 3009c. the dried product was dissolved in distilled water, filtered, and again denied though the precipitation and drying procedures. The final product was entirely white, leaving no visible svideme of tin resin, but a slight odor of ludrcgen chloride was detectable. A Fla-e analysis of a solution containing 10!» p.p.n. of the purified rubidium chloride showed a smell flue intensity at 767 nu which was not detected during eluticn . Evidently at the dilution used for analy- sis in the original sepu'etion procedure the mount of the constituent responsible for this flame intensity was below the detection 111m at the fluephotoneter under the Operating conditions used. In an attempt to determine the source of this flame intensity at 767 am a 0.5 g. ssnple of the purified rubidium chloride was again carried through the elution process under the anus conditions. The elution was followed by taking aliquots from the middle of the fractions containing rubidium. These were evaporated on a steam bath, dried at 120°C, weighed, and an sppmpriste amount of distilled water added to give a 1000 p.p.n. solution. In every angle the {lane intensity relainsd 26 constant, and, within experimental error, equal to that found in s solu- tion containing 1000 p.p.e. of the purified rubidium chloride. Since a second pass through the solar: with a snellsr smple did not reduce the flue intensity st 767 mu it seemed that e further ed- justasnt of operating conditions was mt necessary. The expected impurities, chm to incomlete separation, are sodium, potassium end casinos. The mounts of those present are discussed under I'Flmephotomtry of Rubidiuu end Cesim." name analysis showed the rubidium chloride content to be @proxi- nately 99.7 per cent. Two other possible impurities, contributed from the resin, ere sulfate and iron ions. The mounts of those present are less than 0.002 per cent for iron and 0.005 per cent for sulfate (30), 2? M18310! 3 cm GWE mos rmne The methods for the extraction of ceeim from pollueite hove. re— cently been reviewed and several specific procedures given (’43) . In the vu'ious sethods there are four reegente used in the initial treet- nent of the mineral. they are lydrochl’orio acid, sulfuric acid, were. fluorie acid and sodium carbonate. Nept in the case of hydrofluoric acid the solutions obtained from this initial treeuent contain silica which is removed by filtretion before recovery of the cesiu. A procedure has been reported by Robinson (31) using lydroflnorio acid in which e fixture of finely ground pollueite end fluorsper was heated with sulfuric acid md cesitm elm extracted with hot water from the resulting cake. Since cesius elun can be obtained in a fairly pure state by re- cryst ellisetion from ester (8) a method using e conbinetion of sulfuric end hydrofluoric acids for the initial treatment of the mineral followed by recrystellieetion of the resulting alum appeared very promising. This procedure would eliminate the silica filtration found in the hydrochloric acid and sulfuric acid treetnents es well es the extraction of the calcium sulfate cake in the floor-spar procedure. The selected pieces of pollueite , found to contain 1:6.53‘ 810., 17.85: 111.0,, 32 .765 ca.o(x,nb) and 1.86% sham), were reduced to 170 nesh. Fifty gr. quantities of the mound pollucite were placed in e pletinus dish and enough distilled eater added to form a slurry. hdrofluoric acid was added in snail portions and the mixture stirred 28 with a bakelite rod. Ithe stirring was continued after each addition of acid mtil the reaction subsided. One silliliter of 50 per cent lvdrofluorie acid for each gran of pollucite gave satisfactory removal of the silica. After addition of the hydrofluoric acid the resulting sisters was heated on a sand bath until a paste formed. To this paste )0 ll. of cementer sulfuric acid was added, the mass thoroughly lined using- a platinm rod, and the final mixture heated mtil nearly dry. . ' Y n» platinm «use and contents sere mama to a large beaker, a. mom of «memes water added, and the solution heated almost to boiling for one hour. After standing overnight the solution was decmted from the small mount of residue and evaporated to a small volume. 0n cooling the crystals of oeaim slum formed. . l‘or recrystallisation the slum was dissolved in boiling water, 10 n1. talun for each pen of alum, and the beaker containing the dissolved elun transferred to a 95°C water bath. After 15 minutes the source of heat was removed fro: the water bath and the solution allowed to stand overnight . During the first five hours of the recrystallisation period the solution was agitated with a mechanical stirrer. The crystals of «sin. alum were collected on a Buckner fumel and washed with cold water. The yield from one recrystallisation of 132 g. of cesiua ales was 39 g. The alums were recrystallised ten times in this manner. Plenephotouetric analysis of solutions containing 1000 p.p.n. of cesium served to follow the progress of the purification. These sole-r tions 1were prepared by dissolving O.h275 g. of the air dried cesius elm 29 in 100 ll. of distilled water. Tshle 17 shows thst after the seem recrystallisation the Ilene intensities at 589, 167 end 780 an b‘eeeu fairly constant. TABLE 17 ME ANISIB W cm AM Add , .g I. 1 . H Sodium . Potassium Rubidim [umber 589 an 76? no 780 m Recrystallio em. 2 ms. s.w. 1.3 no. 0.08 m. » sations Instrument no» ; l Be _ ~:. Ins , 2 9 ‘ 62 8 3 ‘9 3h 1 h 12 36 1 5 1° 33 1 6 9 32 1 7 13 32 1 6 9 30 l 9 13 31 1 10 13 33 1 Gesiun slum us converted to the chloride by precipitating (luninum with monies hydroxide and sulfate with barium chloride . .cesiun chloride was recovered from the resulting solution by evsporstion end 1mm» st 500%. for flue analysis e solution containing 1000 p.p.n. of cesium see prepared by dissolving 0.0317 g. of cesium chloride in 25 ll. of distilled vster. The lines assets-ed were those at 589 a (sodium), 767 nu (petusiun), end 780 mu (rubidium). The results ere shows 'in Teble 1. . 30 For further purification the method of Archibald (2) was used which takes advantage or the difference in solubility of rubidim and cesius iedodiohlorides . After seven recrystallisation the iododichlorides were converted to the noraal chloride and a solution contdning 1000 9.13.1. of ceeim prepared for flame analysis. In Table V it can be seen that rurther purification has been obtained by recrystallising the iododichlorides . mm V ME MEIB a cam GMIDE Instrument Readings an an m cesius chloride 32* 10" 7* Purified through alums cums chloride 8* 1 .0M 2* Purified through Iododi- chlorides “*Instrulsnt sensitivity of o .1 Instrunsnt sensitivity of 1.0 No attempt was made to evaluate the effect of s large mount of cesium upon the flame intensities o: the other alkaliea. By comaring the flaso intensities in Table 7 with the nuns intensities obtained tron solutions of the respective alkali chlorides the sodius, potassiu- and rebidim contents are less than 1 Popm. respectively thus giving a cesius chloride content of nore than 99.7 per cent. 31 MEMCIH'H (3 mm m cm In considering the ion enhance experiments described in this thsis it was necessary to have a method of analysis for sodim, potassium, rubidium and cesiun which would be rapid, single and capable of detect- ing shell mounts. In previous ion exchange studies of the alkalies We methods were used; one in which the activity of certain radioactive iso- tapes was measured (9,23), and another using a flanephctonetric pro- «den (7). The flmephotoneter was chosen to follow the ion sash-ego separations and to analyse the purified rubidium Imd cesium chlorides. Recently the flnsephotometer hes found widespread use and many papers have appeared describing its adaptation to the detersination of sodium and potsssius (16) . The literature dealing with the flanephoto- netry of rubidium md cesim, on the other hand, is very limited (3,!“ 13,17,h5) and procedures for the determination of small amounts of sodim, potassiun and cesium in the presence of large amounts of rubidium are wholly lacking. The flneephotoneter employed was one supplied by Beclassn Instrunents Incorporated, South Pasadena, California, catalog umber 10300. The instrment , as well as its operation, is described in Beoknan Bulletin 1934 (3) and by Gilbert 33 g. (17). The first considerations in developing a flsnephotonetric pro- cedure for the alkali metals were those of selecting the proper wave- lengths and flute conditions . 32 In selecting wavelengths those were closes at which the least count of we respective alkali metal could be detected in m oxygena- nstural gas flue (17). Thus m respectively 589, 767, 789 md 850 no for sodium, potassium, rubidium and cesiun. In adjustig the im- struwnt for the proper wavelength, the wavelength dial was initially set to these values and than, with a sample or the respective alkali metal spraying into the flame, a final adjustment made to give a Essie m intensity reading. The Beckssn amphotometer new be used with several combinations or gases for excitation of the elements (3,17) . These are oxygen- natural gas , oxygenesdotylsns and hydrogen—own. (Jason—natural gas was shun since, (a) it is the most convenient and most economical to use, (b) the (lane temperatures for exciting the alkali metals are unpuatively low, and (c) it has a favorable nu. background for those areas of the spectrum to be utilised (3,17). The flame conditions , which are regulated by the relative gee , oqgen and air pressures , determine to a considerable extent the in- tensity of the enitted radiation. These pressures for the various ele- ments were deternimd using the procedure reccmended by the nmtecturer (3) . In general potassium, rubidium and cesium emit more intensely in a cooler flame than that where sodium omits the most strongly. For fixed air and gas pressures the flue intensities of all four alkali metals go through a madman es the cages pressure is increased. 33 In the case of find osflen end gss pressures the flue intensity o: sodium goes though s sexism es the sir pressure is increased while tin flue intensities of potassium, rubidiu- end cesius psdnelly imesse. The psrtioulsr flue conditions chosen ere shown in mm VI. TABLE VI FLAME OWRICIB M TE W was w~ , . ‘- m Wmlength Gss Prams Air Pressure Ongon Pressure Alksli Hotel In n.1sopropyl Inches of p .s .1. Alcohol Wster Sodius 589* 2 15 :0 Potusinm 767“ 2 22 1h mum 780*” 2 22 12 cum. 852“ 2 2'2 12 I *Blno sens itivo phototube sensitive phototubo After hsving decided upon wavelength settings end Ilene conditions for the respective elkalios it was necesssry to choose s slit width thst would be wide enough to snow detection of small amounts yet be mow enough to resolve tb serious spectral lines. The spectrel lines that ere the most subject to nutnel interference are those of potassium st 767 end rubidium st 780. To determine the maxim slit width thst could be used end yet resolve these two spectral lines the instrument um- lsngth disl no set st 780 m and 2 solution containing 100 P.P.I. of potassium es the chloride sprsyod into the flue . with the selector 3h switch of the Bechan M Spectrophotoneter in the 1.0 position and the variable sensitivity knob in its countercloclo'ise position, it was found that a slit width of 0.06.. could be tolerated without producing any flue intensity above distilled setter beckpound. After several ion exchange runs the slit width was reduced to 0.0}: on. am this value used for all the work reported. The eluant used in the ion enhange separations was wdroohloric acid, varying in concentration fron 0.7 to 1.5 neural. Due to the add- verse effects of twdrochloric acid on the natal parts of the burner eech sample was first evaporated to dryness in platinu- sure. i The instrunent conditions chosen for following the ion enhance separations were: flame conditions an wave lengths as shovn in Table VI, slit width 0.0!; an” selector switch in the 1.0 position and the variable sensitivity knob in its full counterclockwise position. The suples for flue analysis were placed in S n1. taken and protected in a Petri dish until reamv for actual analysis. The procedure for analysis, after instrumnt warn up and adjustment, consisted essen- tially of the folloving steps: 1) a sample of distilled water was sprayed into the fleas and the background deternined. 2) The sample beaker containing the snple for analysis was moved from the Petri dish and placed in position. 1'13 fleas intensity was determined, the s-ple replaced by distilled water, the dark current and instrment gauges checked, and the flame intensity of the sample again determined. 35 3) If the that m flane intensities speed new; 0.5 of a unit no further neasurenents were made; if not, the procedure was repeated. In some samples of high concen- tration where the level of liquid in the ssnple beaker had an appreciable effect upon the reading the beakers were refilled for repeat neesurenents. h) The 11m value for the am intensity was determined by subtracting the background intensity of distilled water from the flame intensity of the sample. If nore than one neasm'esent sure to be nade on a series of seaples, for smile both rubidiun and cesim, all staples in the series would first be malysed for rubidiun or cesim , the instrument conditions changed, and then the series again analysed for the next mount. Calibration curves for rubidium md cesiun over the concentration range encountered are shown in Figures 10 and 11 respectively. In these curves no correction for the effect of one alkali netal upon the other has been made. Since this is an enhancement effect the values obtained for the areas of cross contamination in the elution curves are naxim rather than nininun values. In determining the purity of the rubidium chloride prepared by ion enhance it was necessary to deternine small mounts of sodium, potassium and cesiun in the presence of large amounts of Midiun. In choosing conditions for this deternination two main factors needed to be con- sideredg the ninislu concentrations of sodim, potassiun and cesium MQEOJIO 2255.; do .2: 9.90 23_o_m3m mo... OVN OON m>m30 20.535340 SD_o_mDm ...O .Emm Om. ON. Om O _ mmaol n___ on 00. LN3iNf-HiSNI SNICVB‘: 220.an m0 «rim QmN-O mo_m0.._Io 22mmo mod m>m30 zo_k<>> 0mm onm 0.0 Om» on» OWL. 00w own. _ll_ 104 . ;~\\* _ .00” _ l _ .nl _ iLL _ l 0 ON ov Om Om OO. SNIOVBH .LNBINnHlSNI concentration of 100 p.p.m. of rubidium. The results are shown in Figures 13, 11; and 15. A third series of measurements was made on solutions containing one p.p.n. or sodim, potassium and oeeim in which nzbidiun was added in vu'ying mounts from 1w p.p.n. to 1000 p.p.m. Those solutions were prepared in 25 ml. volmetric flasks by adding one :1. of 25 13.13... solutions of sodium , potassium and cesium . The varying rubidium content was introduced by adding 1, 2, h, 6, 8 and 10 ml. of a 2500 p.p.n. solut- tion of rubidium. Figure 16 allows the effect of increasing newts of the purified rubidixm chloride on these one p.p.n. mounts. Tm recommended procedure for compensation of interference that cannot be removed is to prepsre a series of standards thet are identical to the sample but contain varying amounts of the element in question (17,27). Then, by a direct comparison at flme intensities the unknown concentration c an be determined with the contribution or the interference taken into account. Since cpectrogrephicslly pure rubidium chloride was not available this recommended procedure could not be followed. It has been shown that when a brillant tlme, such as obtained rm appreciable concentrations of sodium, is produced the line often is not resolved and there 1- an increased emission at other wavelength- (3,h,17) . figure 12 represents this phenonenon with respect to rubidium. In Figure 12 the peaks at 780 no. and 800 nu are rubidium lines, while the one at 767 um indicates the presence of potassium since rubidium has only a week line at 767 mu, which probably is not excited by on INSTRUMENT READING I00 80 60 4O 20 I T I I A — -—I B I—- — I—-— —-4 — fl L l l L ' 2 3 4 P. RM. OF SODIUM FIGURE i3- EFFECT OF IOO RPM. OF RUBIDIUM ON THE FLAME INTENSITY OF S ODIUM CURVE A SODIUM CHLORIDE 'I' IOO RRM. RUBIDIUM CURVE B SODIUM CHLORIDE INSTRUMENT READING I00 60 4O 20 F I _ A -_ I— .— F.— _ B I-— 1 I a L I 2 3 4 F.‘ 'F.‘ M. OF POTASSIUM FIGURE I4 EFFECT OF IOC‘ F’.F:M. OF RUPIFIUM ON THE FLAME INTENSITY OF POTASSIUM CURVE. A POTASSIUM CHLORIDE‘I’IOO PPM. RUBIDIUM CUR'EE B POTASSIUM CHLORIDE INSTRUMENT READING 20 0' O J J I I 2 3 4 RPM. OF CESIUM FIGURE I5 EFFECT OF IOO PPM. OF RUBIDIUM ON THE FLAME INTENSITY OF CESIUM CURVE A CESIUM CHLORIDE-I— IOO PPM RUBIDIUM CURVE B CESIUM CHLORIDE mmoEoJIo E; m4 $5.30 ozq {5.359. .2358 do 2?. _ do mmEmzmhz. m2