vo= 17 (1957) POTENTIOMETRIC TITRATIONS. III. 521

ZUSAMMENFASSUNG

DICSC Arbelt cnthalt Tabellcn SOWIC clmge veremfachtc Betrachtungen, dlc es dcm mcht m dlesem Spezlalgcblct bcwanderten Analytlker crmoghchcn, fur die Titration in nlchtwassrlgcr Ldsung dcr melstcn tn dcr analytlschcn Praxes ubhchcn Saurcn und Bascn geclgnetc Bedlngungen zu wahlcn Ferner werdcn Tabcllen, dlc bcl dcm Tltrlcrcn von Mlschungcn ntcht 7u ahnhchcr Saurcn und Bascn zum Lcttfadcn tllcnen k&mcn, sowlc Bclsplclc fur dlc Bcnutzung cllescr Tabellcn gegcbcn

REFERENCES

1 H B VAN DER HEIJDC AND E A 31 F DAYIMLN, Anal Chzvr A&a, 16 (1957) 378 2 i-i H VAN DER HEIJDK, /Inal Chrna ricfa, 16 (1957) 3gz J \’ Z DEAL AND G WYLD, Anal CJtettr , 27 (195s) 47 -. . 4 G I, lJ~~~~~~ ASD IC A ICOBE. Tram /3lcclrochem Sor , 74 (1938) Gag 6 W 1-l BROML~Y AND W I: LUDCR, J Am Chon sot * 66 (1944) 107 a J S FRITZ ~hr~ IM 0 FULDA, Anal Chenr , 25 (1953) 1837 ’ P Sr.us~ AND G G GALLO, rlwr clltm (Rome), 43 (1953) 453 B F E CRITCI(TII:LD AND J B JOHNSOS, APIUZ CJIFWZ, zd(lg54) 1803 @ J S I'KlTZ, ,-f~ul Che,,t , zz (1950) 1028

10 J S I+ClTZ, .4 tla[ Chem , zz (1950) 578 11 A A MARYOTT, J Hcsearcla NatI Btw Slaudards, 38 (1947) 527 ‘* A 1: GKRMlLI ION. rlnn/ CJwnt I 27 (1955) 133

Rcccl\ccI \ln\’ zoth, 1957

Nole added 111 proof

It has been mcntmncd in Part I that the tctraalkylammonlum bases usccl arc unqtahlc in pyrrdlnc at room tcmpcraturc Accortllng to C K INGOLD (Sfrrtcl~rrr nud ~~erlrnnrrm tn Orgnntc Clrernasfry, Cornell University Press, Ithaca, N Y , 1953), suhstltutmn of the alkyl chains at tlrc /3-po\ltlon with an clcctron-donating ratllcnl Increases the stnblhty townrtls the blmolcculnr climlnatton of olcfln In accordance with thcsc VICWS WC have fount1 trlmcthyl-zsobutyl- ammonium hydroxltlc to bc complctcly stable In pyrltllnc at room tcmpcr&urc As the solvatlng propcrtics of tlils partlcrilar base may not hc suffiLicnt for all purpose\ it might lx profltablc to prcparc an analoguc with more or longer p-ramlftccl alkyl ch,Llns

THE FLAME PHOTOMETRIC DETERMINATION OF CALCIUM IN PHOSPHATE, CARBONATE, AND SILICATE ROCKS

by

HENRY ICRAXIER*

U S Gcologrcal Swvev. Wnslungfon, D C f U S A )

INTRODUCTION

Investlgatlons of the flame photomctnc detcrmmatlon of calcnun have been made on glassc9, mmerals2, blologcal matenalsa, metallurgical products4, and water sam- plcsb Techmqucs usually involve either the prchmmary separation of calcium from interfering elements, the addition of a saturated solution of a radlatlon buffer to provide uniform radiation charactcristlcs and mmrmize the interfering effects of diverse ions, or the comparison of the unknown solution with a standard that incorporates some or all of the mterferenccs present m the unknown solution. In the latter proce- dure for accurate quantltatlvc analysis the qualitative make-up and approxlmatc quantities of the components present m a given 5ubstancc must be known. __ __- __.. --_

* Publlcatlon authorized by tho Dlroctor, U. S Gcologlcal Survey. Prcqcnt acldrcss New Bruns- wick Laboratory, U S Atomz Energy Comnusslon, P. 0 Box x50, New Brunswick, New Jersey.

- References p. sag

522 H. KRAMER VOL. 17 (1957)

Our problem was to determme calcium m phosphate, carbonate and silicate rocks contammg varymg conccntratlons of the usual rock-forming elements. The method was to bc apphcablc to routine work, and the utmost m accuracy was not required.

Although most elements either enhance or suppress calcium emlsslon to some extent, aluminum and phosphorus cause serious suppression. This effect has been noted by many investigators, iblosmzn el al. partially overcame the effect of alummum by the addition of a rclatlvely large amount of magnesmm 0 In the procedure dcscrlbccl here the interference 1s almost entirely overcome by the addltlon of a large excess of mag- nesium. The method 1s apphcable to the dctermmatlon of calcium m theafore-mention- cd rock types Separations arc not required and the results are better than f 2%

of the calcium oxide found by &ravlmetrlc methods m the x-~Js~/~ range. The method compares favorably with standard methods m the o-r”k, range, and the lower hmlt of sansitivlty is o.or%.

Thus study is part of a program-conducted by the Geological Survey on behalf of the Division of Raw Matcrlals of the U S Atomic Energy Commlsslon.

lXP1~IZIMENlAL DATA

Tho most scnsltlvc calcium band I\ at a wavclcngth of 554 m/-L u4lng the blue-scnsltlvc phototubo The oxy-hyclrogcn fl,Lmc was sclcctccl bccau~ of the f.rvorablc cmlsnon-to-background ratlo.

fnlcrfercncc sturllcs wcrc maclc by adding various amounts of nltrlc acd to 30 p p m of calcium

IO 20 30 40 so

--CALCIUM (ppm)

F1g t _ Standard curves for calcium at 554 rnlc Curve I o-50 p p m Cn _t 20 ml radiation buffer, slit wlcltti 0 057 mm Curve II 0-50 p p m. Ca as NO,, sht wltlth o 047 mm Curve III o-5 p p m Ca -C 10 ml rachntron hnffcr. sht width o I 12 mm

References p ~a5

VOL. 17 (1957) FLAME PHOTOMETRIC DETERMINATION OF CALCIUM 523

I.

unt11 no further radiation suppressron occurred Next, the effect of pcrcl1lorlc ac~rl 1ncrcments was tested on 30 p p m of calcium plus the plateau quantity of nitric nc1d clcterm1ned m the preceding cxpcr1ment until another plateau was reactled Succccdmy clcmcnts were studled 1n this order alummum, phosphorrc ac1t1, magnesium, Iron, sodium, potassium. and manganese to establish plateau quantitlcs These experlmcnts tlctcrmlncd d radiation buffer containing all the elements that affect calcium cm1bslon In such conccntratlons that supprcsslng or cnhanclng effects wcrc ovcrcomc In the proccdurc devclopcd, the radiation buffer 15 adtlcd to botl1 samples and standards so that the conccntrat1on karlat1ons within the samples thcmsclvcs arc wlthout cffcct on the sample cn11sblon The radmtlon buffer also provides 1ncrcasctl flame stnb1hty and m1n1n11deY drift so common to flame methods Uurncr clogging dud not occur The radlat1on bufferalmost completc- ly rcstorcs the stanclard curve obtalnctl from an aqueous solution of calcium nltrntc rw shown 111 Fig I Cahbrat1on curves for the ranges 0-50 p p m and o-5 p p m calc1un1 are prcscnted

Intcrfcrcncc stucltcs 1ndlcatccl tl1c following comcutratlon 11m1ts for the malor rock-formlng clcnicnts

Co,islllrienl ~n~/roo ml -- _-- -_-- 4% 100

higO 100

P*O, 60 FC,O, 15 Na,O (no upper lln11t cstabltshcd) ‘5 K,O (no upper limit cstnbhshed) 7 MnO 13

Nitric acid and pcr&lorlc nc~d tolcranccs arc Go<, v/v ant1 z 5:{, v/v rcspcct1vclv On the I~.IYIY of 100 mg of s,1mplc rnaclc up to I ooml a5 tlcscrlbctl below, the sample cd11 rontJ1n

GoTi, PaOe, I+‘{, Fe,O,, i so/;, 1N.1~0, 7?,, K,O. and I 3q;, MnO Thcsc tolcranccs permit the ,rnalys~s of most phorphatc. carbonate, and slllc.itc rocksw1thoutcl1a1~g~ngtl1eproccclurc \Ilnor rock-form- ing cloinents such ab chromiuni. titaniuin, vanatlium. 11tl1111m, ant1 hariuin. unless prcscnt ‘as nialor constituents, do not intcrfcrc

4 13cckman n1oclcl I>lJ spc~trophotomctcr with a model Q2zo fl.imc attachment and a model 4300 pl~otomult1pl1cr was used with an oxy-hvtlrogcn flame

Ik4qeiats

I-lytlrofluoric acid. 4!37& Nltrlc acid, (I -/- I) Standard calcium solution (1 ml -1 1 00 nig Cn) Ihssol~12 a .)g8 g of reagent-g1ddc calcium

carbon,Ltc drlctl .Lt 105°C In IO 1111 of (I + I) nitric acid, ttansfcr to a I -Iitcr volutnctrlc flask, and dilute to mark with water

l<.1tl1atmn buffer Wclgh the following into a .;oo-ml bcakcr. al11mlnum rnct.11. foil o 005 Inch, 4 000 g, ni.ijincsiuni ribbon. 9 000 g# iron w1rc. 0 500 g, sod1uni nltratc, 2 957 g. pota54iuni nltratc, o 776 g Cover w1tl1 .L watch glass, add IOO ml of conccntratcd nitric acid (add adtllt1onal nltrlc aacl If ncccssary). and evaporate to dryness I~;ssolvc the rcsicluc In rzoo ml of (I + I) nltrlc acid and heat to effect solution I;lltcr through a f1nc paper 1f the solution 1s turbid

Prcparc a standard phosphate aolut1on (K ml r~ 50 mg phospl1orus) by p1pcttlng 11 o ml of 85%, phosphoric acid (sp gr I GQ) Into rl zoo-ml volumctr1c flask and diluting to volume with water Stanclardi/c

The radiation buffer 15 prepared by addIng a volume of the phosphorrc acid solution cqulvalcnt to L 50 g phosphorus to the cntlrc mtxed-salt solut1un and diluting to z liters 1n a volumctr1c flask

When a no-ml al1quot of the buffer IS d1lutcd to IOO ml It contains 400 p p m al11m1n11m. 250 p p m phosphorus, QOO p p m magncslurn, 50 p p m iron, 80 p p m rodlum. 30 p p m potassium, ancl G ml of nitric acid

Calcium standards cqu1valcnt to 50, 40, 30, 20, 10 and 0 p p m arc prcparccl by pipctt1ng 5 00 ml, 4 00 ml, 3 00 ml, 2 00 ml and x 00 nil of the standard calcium solution into x00-ml volumetric flasks, adding to each 2 5 ml of 75%, perchlorlc acid. 20 ml of the radiation buffer by plpctte, and diluting to volume with water

Procedure Wagh o 1000 g of sample Into a platinum dish, add 5 ml of (I + I) nitric ac1r1, 2 5 ml of 75o/o pcr-

chlor1c acid. and about 5 ml of 47 o/{, hydrofluor1c acid Evaporate on the steam bath until the first Iumcs of perchlorlc acid appear, wash down the s1cles of the dish with water, and aga1n evaporate to the initial appeardnce of pcrchlor1c acid fumes Repeat wrth addtt1onal n1trrc and hydrofluorrc

References p. 5~15

524 Ii. KRAMER VOL. 17 (1957)

acid If ncccssary Add about zo ml of water and dlgcst on the steam bath to cffcct complete solution. Transfer to a loo-ml volumctrlc flask, cool, add by plpcttc zo ml of the radlatron buffer, and dilute to volume with water

If the sample IS cxpectcd to contarn over 7OA, calcium oxldc, make an approprlatc dllutlon before addlng the radlatlon buffer so that the calcium conccntratlon IS less than o 05 mglml

If the sample IS low In calcium (2 e , < o 507&), carry a reagent blank along with the sample.

Spcrlvoplrolometer sellzngs Wavclcngth - Scnsitivlty cant% m” . - 5 turns from clockwlsc limit, Sclcctor switch - 0 1, Phototubc - blue with 22 mcgohm rcslstor, Slit - o 057 m/r, Hydrogen - 5 1~51, Oxygen - 10 psi, I~l~otoinultipl~cr - full scnsltivrty, Zero supprcrsion - off

TABLB I

ANALYTICAL UAl-A

1 yps of aanlplc Calmon oxtdc

colltml %

NBS IA NBS 56 13 NBS 79 NBS 80 Nl3S 81 N13S 88 N13S 91 NBS 98 N13S g9 NBS 102

NUS 104 NBS IZO NBS 128

USGS W-r USGS G-r

f.imcstonc 4’ 32’ Phosphate rock 44 06 Fluorspar 94 83 Soda-hmcglass 4 65 Glass sand 0 029 Dolomite 30 49 Opal glass 10 48 Plastic clay 0 21 Fcldsp,ir o 36 Slhca brick 2 29 l3urncd magncstte 3 35 Phospllatc rock 49 62 Soda-IlmcglJss 4 76

Standard diabdse St.mdard granite

I3rcr_clatcd hmcstonc Calcaroous clay Clayey sand Conglomcratlc hmcstonc Apatita

Phosphate rock 8, I, ,I ,I

Pho~~~llatlc lt&!stono

10 95= 1 35a

50 46= 4 58 o 48 I 80

49 so

1 96 6 01 ‘ 40

dl2G 24 35

Pllo5lJllatlc clay 0 22 Alummum plwqJh.rtc: rock4 69

,, 0 *, I 41 ,I II ,I 119 ,, ,* ,I 86

,, I, 0, I 57

40 6 43 9. 43 7 96 6

4 65 o 034

30 6 IO 6, 10 7 0 18 0 38. o 38 .! 36 3 42

49 41 49 4 4 72~ 4 75

I1 0 I 36

50 o 4 65 0 55 ’ 74

48 7, 48.5

2 02

5 93 1 45

21 95 24 22

o 23 6 75 ’ 70

I2 I 8 60 I 68

1 NatIonal Bureau of Standards ccrtlfrcatc value a Avcragc valuo 3 Slmplc prcclpltatlon as oxalatc and volumetric detcrmmatlon with potassium permanganatc. 4 Sample 12-16 from the aluminum phosphato Tone, Bone Valley formatlon, of Plrocene age,

Florlda, usually contaming wavclhtc, crandalhtc, quart?, and kaohmte

Relerences p. sag

VOL. 17 (1957) FLAME PHOTOMETRlC DETERMINATION OF CALCIUM 525

Flame QJrotometvrc pyocedure While the 50 p p m calcium solutron IS aspuatmg, adlust the wavelength dral to erthcr side of

554 rnfl to obtatn maxrmum transmrssron with a mmlmum slit wrdth .4dlust the 50 p p m calcrum standard to read IOOO/~ transmrssron using the slit width knob After this adjustment has been made, mstrument drift 1s corrected by minor adlustment of the hydrogen gauge regulator The sample 1s then analyrcd by brackctmg between the closest calcium standards Three readings arc taken on both the sample and the standards and they should agree to f x0/o Calculations are based on the assumption that the curve 1s linear bctwecn the IO p p m lncremcnt

After each sample aspirate water through the burner

SUMMARY

A flame photomctrm method of determnnng calcrum m phosphate, carbonate, and slhcate rocks has been dcvclopcd Aluminum and phosphate :nterfercncc was overcome bv the addition of a large cxccss of magnesium The method 1s rapid ancl suitable for routmc analysis Results obtained are wrthm & z”A, of the calcium oxide content

Une methode photombtrnlue a la flamme, pour la d&crmlnatron du calcium dans lcs rochcs phosphat6es, carbonat&s et slllcatbes a dtB d6vcloppdc L’lntcrf&ence do l’alummlum et du phos- phate a Bt& &vltbe par l’addltlon clc magnt%tum en grand excbs La mdthode cst rapldc et convenable B l’analvse courantc L’crrcur dans lcs rdsultats cst dc rf: 2% de la tcneur en ovvde de calcium.

ZUSAIMMENFASSUNG

Elne flammenpl~oton~ctr~schc Mcthodc fur Ikzstlmmung von Calcium In Phosphat, Carbonat, und Slhkatgcstclncn wurdc cntwlckclt Die Sthrung von Alummlum und Phosphat wurde fiber- wundcn durch Addition grosser Mengan Magnesmm Desc Mcthodc 1st schnell austufuhrcn und wlrd fur Routmc-Analvsen empfohlen Calcmmoxvd kann mlt emem Fchler von & 2% bcstlmmt werden

REFERI<NCES

1 NORMAN RAY, A,lal Chem., 28 (x956) 34 2 S R KNIGHT, W C MATHIS AND J R GRAHAM, And Chew , 23 (1951) I 704 3 G R KINGSLEY AND R R SCHAFUERT, AuuC Chem, 25 (1953) 1738 4 D 17 KUEMMCL AND Ii 1, KARL, Anal CJtotr , 26 (1954) 386 6 P W WEST, 1' FOLSE END D MONTGOMEHY, Aual. CJrem, 22 (rg5o) 667. 6 R E MOSHER,E J BIRDANDA J BOYLE, A~al. Chetn, 22(x950) 715.

Rccelvcd April 15th. 1957

Short Communkation

Thermolysis of the molybdenum(W) 5,7-dibromo-8- quinolinol chelate

One of the methods for the determination of molybdenum(V1) ion is by precept tation as the molybdenum(VI) 8-quinohnol chelatel. The precipitation was found to be complete m the PH range of 3.3 to 7-G. In order to carry out the determmatron m more acid solutions (PH c I), RAMANA RAO suggested the use of 5,7-dibromo-8- quinohnol asa preciprtant2. A flocculent, orange-yellow precipitate was obtained winch was easy to filter and wash. Smce thrs method appears to be superror to the exrstmg 8-quinohnol method, it was of interest to study the thermal stability of the precipitate on the thermobalance.

The molybdenum 5,7-dibromo-8-qumolinol precipitate was prepared as prevrously descnbedz. The compound was air-dried at room temperature for 24 hours before pyrolysis on the thermobalance. A heating rate of 5.4% per minute was used.

Ra~e~errccs Q 96