The use of sulfamic acid as a primary standard in nonaqueous titrimetry

VOL.

21 (Iqjcj)

ANALYTICA

CHINICA

ACTA

205

Since tlic choice of primary stuntlards for wc in non;u~ucous titrimctry is limited, tllc possibility of using sulfamic acid in tlk field would lx: most acccptablc. Sulfnmic acid is an inorganic compound with n rclati\*cly simple structure. As a primary stanclarcl it lias many ndvuntagcs’. It is clw;ll~. rciltlil~ avaihblc, and can lx easily purified from tlic tcclniicul graclc product, from which it scparatcs as 8 scopic, wliitc crystalline matcrixl. 1t is a rcliablc stm-darcl wlicn usccl solutions. ‘1’1~ reagent is solul~lc in the basic solvents currently used in titrations, anti work tlcscribctl in this paper has sought to evaluate tlic of using sulfamic acid as a Stil~ltl:llXl in tllcsc titrations.

non-hygroin aqueous nonaqucous

possibilities

In rc~rz Fol.ls :\.wx) lTI.hs1)121e~ c.strxActl bcnxoic acid wit11 cliloroform ant1 succccdctl in titrating it in lm~etic. Conscqucntly, lxnzoic acid cluitc naturally cnmc into use for the staiirlarclization of tlic alko.siclcs and alnino-ctliosides with tlic aclvcnt of tlicsc titrants. This acid clissolvcs readily iii dirnctliyl forrnaniiclc and cthylcncclinminc and gives reproducible titrutioiis. It has provcci unsatisfactory for titrations in lmtylnniinc, howcvcr, since tlic formation of a gel produces erratic results. Crystallinc plicnols arc used in place of bcnzoic acid for this latter solvent. ‘Hicsc matcrinls form tlic chief primary St~l~ldilNlS in use today for tlic nonaqucous titrations of bases. If sulfamic acid proved a good standard in tlw solvent, wbutylaminc, it coulcl then bc tccommcndccl for USC in ~~onuc~ucous titrations pctfotmccl in the common basic solvents. This work has succccdcd in titrating sulfamic acid in all of the commonly usccl basic solvents by both visual ancl potciltiomctric means. One pliasc of tlic work 1~4 sliown that it is possible to titrate sulfamic acid in an acidic solvent. By conductomctric means, silifamic acicl was titrated wit11 pctclilotic acid in a glacial acetic acid system. One difficulty, prczxnting itself at the outset of this work, was the prcdictablc low solubility of sulfamic acid due to its highly polar nature - in tlic organic solvents frcqucntly usccl in nonuqucotis titrimctry. ‘I’liis prccliction was justified and sulfamic acid ptovctl practically insoluble in clioxanc, bcnzcnc, carbon tetrachloriclc, methanol, ethanol, isopropa+31 and glacial acetic acid. However, it was found that sufficient ______ ..--+ (n) Prcscntcd in part bcfurc the SIcctillfi-ill-;\liIliiltllrD uf the lvcw Yurk Section of tlw Amcricrrn Clwrnicnl Socicly, March I .I, 1g58. (I>) J.&cd on cxpcrimcntal part of tlwsis sllbnlittcd by Sr. Xlclrgwritc Xliriarii Case, S.C., to the Gracluatc in partial fulfillrncnt of rcquircmcnts for tlic dcgrcc of ** Prcscnt arltlrcvs of nuthor, Collcgc of Mount Saint Hcf.?ve,1ces p. 21.g

Scllod,

tlochxof Vincent.,

I:ordhatn University, philosophy. Xew York 71, N.Y.

June

1g$3,

zoG

.\I.

Stlifi~Jllic

Wit\

to gi vc:

ii

tlissoivt:

rcacliiy

in

titc

tiic

with wit11

rarqc

pair

ant1

J.;JJ.I_IOTT

tilt!

tftat

ti~c

I,xsc:li~~

wccl

tiw

soclirlJn

~lricsc

~1~s

Jnctilosiclc

liter~~ttrrc

I~rcliminnry

for

a~iut!oti~

caion~t:I

c~ilomcl

c:lcctrotir:

or IitlliuJn

ln

sdt

in ctiiylcJle(iian~inc.

soii~ticm

lithium

chlrtriclu

in

tile ‘i’ltc

was

cllloridc:

not

bccuusct climctliyl

its

clcciroclcs

wcrc

successfully

titis

usd

for

11s~: of in

c3rdr:r

titrations

appear

q-Mom tlkc

tllc

attention

bcctl

ASI,

in butylutnint:

rcl>cJrtd

fit.

by

authors

i’itIT%

c’icids

constant

and

liytlrrq2n-

system.

of c.4

first

inciicator~icctrodc

iL17CltllCSc

tiiscrsc

d~ctroclc

indicators

titrations

used

irusc

I-iowc\*cr,

of

wcrc in

rccluirccl

sulfoxidc.

irtck

‘I’lic

I..t’ICl<15S’i

it

phitinum this

with

lising

beilavior

Sr3llttioJl

of

was

chosen solvent.

form:unidc~~.

at

in

tliis in

ctspcrimonts

of

of IithiuJn

of

c!lcctrocl.lc Worii

salvcnts

stage ti trutions

of

tilt:

its

in

in the

tilt glass

incrctrsucl

Was

iJl~Csti~~tti~)xi, basic

over the

l-LU.1.~

C3f thC

Same

rcpfaccd

in ~iJl~~tlly1

the

formamiclc, yotnssiusn

most

or

promising

it,

and

a study

l’l~ymol

solvents

had

an tile

chloride AND

:L solution

with

eJi~ikkn1

when wlliclr

potassium

solubiiity

coxitinuccl

in

lS1.r.Io*rT

forJlliLnlide, cilloridc

platinum-

good

tnadc

cithcr hloss,

wit11

tlrc

not

CC3Jlll~~l~ilti~3n provccl

is still

involving

of

was were

of

cliloriclc

in diJlli:tilyl

‘I’llis

so

solutions

lX3titSSiUJn

bccuusc

basic:

sensitivity

ctiiyicnctlinniillc,

solution

inVcsLi#iti0JW,

incliakturs

cllc

~~~13r~ciLlcil~iiity

n~n;~~lu~oi~s

lC1-t\N lo, Worliitlg

in liic

rcvoalcd

furtiicr

so

tlkc r;olvcnt,

a snturntecl

accuracy

wori~

13aSic Jncclia, tmxl

wit11

iLtt.~llll?tCCl of

was

arlllc0US

i>rcliJllillilry LISC of

in

XViLS fillutl

I?_!~)lilCcd

sotli~lnl

the fur

@.ZhXtrcJCk

iIil(I

;ui~icous

USC of

titrntions

cllioridc. tllc

Platinum

wcii

to and

acid.

titrations

min,

soivcnts.

itivcstiiptions

system

for

Io found

acetic

pair

fl~tlCt~ol1

tiliit

etilylen~~lii~llliil~~~~.

tile

l~isic

not

warned

and

in ctI~yir:t~cdiamiJle,

~~~!~l~~~l~~lll~~~lilIi~J~.

but

climcti~yl

;i Chioranii

in ~iacini

for Was

9t-hutyiamine the

realixod,

cicctrde

did

acid

untried,

AXJ> I-i,rr.r, 3 used titrations

@ntiy

titrations,

was

com?~in~d.ioti

results.

Wld

~1x1 both in

c:tlond

in

systc111,

tctrailycirofur;~n7

pn:viousiy

titIXthls

for

1

clr:ctroclr:

rcproclucibl~

dcctruclc

for

Sdicl

Suifrtmic

formnmidc,

in n~nitfiu~ous titrations

clcctrodc!

tile

imlicntor.

dimc:tl~yl

&3lvcnt,

wvrk Cc3l;,\S*r

HALL

rcfkkng

violet

(1959)

VOL. 21

CEFOLA

zlftcr

solvents,

C1’i;Lss-;ttitimo~~y

h’iass-c;1iomc:i

to

the

M.

~LntiJnony-antiJ_nony

ANI>

rcl3ort.d tvitlk

basic

pf3tcntioJnctricaliy.

cdonici

xid,

ucicl-base

for

:L c;ilu~n~~i refercncc

MOSS,

ti1c

of

CASO,

to crystal

in ik fourth

ht:ginning

a suitdlc

13crf0rnlctl

tlircr:

and

vt:ry

acctk

lxisic

A’

ctl~ylcne-<.li;unille, in

in

diWJi\Wd solution

0.05

M.

bluc~l

in @ma-al,

of

indicators

was

chosen

particularly

21

VOL.

(1Qjg)

STANDARD

IS

SOSAQUEOUS

TITI~I~I1~TII\-

207

Reagents Sulfirrnic acid (Primary standard grilclc. 1+%5llcr), xvim rccrystallizccl Irum water scVcrn1 tirllcs llntil it g;ivc: 110 c,p;ilcsccncc wit11 barium chluritlc. ‘I’Iw rcngcnt was clriccl at 10ejo fur 3 h a,ncl its plrity was nssnycrl according to the tncthotl of rWTLI!K, SarrrI1 ASD AuI~HII:TI~*. I’otnssiuni acicl phtlmlntc (L’rimary standard grnclc, SIcrck). was clricd at 145~ fur 3 Ii. Jr-Uutylnminc (?‘cclinical, I<:rstman). \\‘ilS tlrictl owr sotliuni l~ydroxitlc for scvcrd clays, tllcn tlrictl o\‘cr sucliiinl for one clay ant1 firi;tl!y tlistillotl. I>imctliyl sulf0sitlc (Tccllnicnl, StC!I’ilIl). was usctl. as reccix-ccl, without further prificatlm. I~tli~lr~~crliii~ilinc (3 j-loo‘%,, IIoss, 1
a WiIS

wILcti1JIl

clarify in

I .V

CliSSIJlvC!tl

;I

ill

c~f

150

IllI

cc~nil)lctc*tl.

was

litliiiini

nictlic~sitlc,

CJf illJSCJllltc

Hjo

Illct~lIlIlO~,

1111 (Jf

tlrictl

ap1~rosim~~tcly ccJI~l111~

l~i:rizcIlc

wc*rc

0.0

I:

of frcsllly

ciit

litliiunl

tllc soliitican. tllc vc~l~lIll~*crf IllC~tllilIlC~llwinc: IClb1>tIlt il niinimlini buttlc.

glilSs-StlJpprCd

J+rcirlovic

acid,

0.2

1)rc,tcctctl

fIXJIll

CitrlIcJll cliusitlc:

IzeI:J. ‘1’1~: rcIqq:nt mail niuistilrc.

titrant,

ZOO--300

0.2

1111 of

WLS storctl

,\

I>?_ iriixiq 17.” Iill IJI 72’!; pcrcl~l0ric 1111c~f acetic arili\tlritlc*. ‘I’llC r1’sllltiIig \vIis ciillitctl to i I witli glacial xctic acicl and allu\vcil to StiLlIt for iit IciLSt 2.) II to permit of tlic I’C’ilctiIJIl Iwt\vccll ilCl!tiC :IIillytlritlc ;llltl tllc \\‘i~lCr lmwntll. (;l;~ci;tl xcc*tic ;Lcitl (Ihkcr). f~ctlzl:llc (iLIllIjdrcJIlS, rcaKcIit gritcIt*, Merck), \vils clriccl owr sotli\lni irlltl clistillccl. ‘I’hC

rnctnl

tllc flask tltlring the mltlition. \Vlwn tlw ilClllC!ll. Slifficicnt lllCtllilllIJl \VilS ilClllCC1tCJ

,\’

fililci;ll

lwrcliloric ILCctiC

ilcitl.

;lCiCl

was

irlltl

1nx2lxrwtl

iltlclillfi

20

;icitl

wit.11

S1lllltiI’JIl

coniplction

x0 ml of solvent wcrc placctl in 8 25.0-ml ISrlcnmcycr flask. A stirring and tllc solution was Illil~l~ctiG.llly stirrccl. ‘fllrcc drops of tllymol blue indicator solution wcrc ndrlcd and tllc sul\*cnt WLS titrated visually with 0.x Nlitl~ium mctliosidc solution to tlic first appearance of a pcrll~ilncl~t, clear blue color. Less thnn 0.01 ml of titrant was usually rcquircd to IlcUtrillixi! the acidic impurities of tlic solvent. Approximately 0.1 g of primary standard was ;Lccuratcly wcigllctl into tllc flask and the solution was titrated by passing 0.1 N lithium mcthosidc cluickly into the flask. As tllc end-point \viLsapprOiLcll&, one drop of base turned tllc solution a deep blue. ‘1’1~ two standards, benzoic and sulfamic acids, were: titrated altcrnatcly in IL series of IO dctcrminations for each acid. ApprAmatcly bar WiLS ad&d

f’ote~ttiontctric litratiom Esactly 0.50 mcquiv. of primary standard was accurately wcigllcd into a tall-form beaker and IO ml of basic solvent, previously neutralized as above, wcrc acldcd to dissolve the sample. ‘I’llc beaker was mounted in the titration assembly described above and tllc titrant was ad&d in small increments. The clcctrodcs wcrc permitted to come to cyuilibrium bcforc the reading was recorded. l’hc titration was continued several ml past tlic calculate cud-point. ‘l’hc platinum-modified calomcl clcctroclc system was used for all titrations in basic solvents. Colzducton~etric titrutiom Exactly 13eferencrs

48.6 mg of sulfamic acid was dissolved p. 2r.j

in 40 ml of glacial

acetic acid and

VOL.

21

STASDARD

(1959)

IS

XONAQUEOUS

TITRIXIETRT

209

other solvent systems, dimethyl sulfosidc, It-butylaminc and ethylcncdiamine. The results are listed in l’ablc II. Thymol blue was used as the indicator for all the solvents except cthylcnediaminc. Azo violet was a better indicator for this latter solvent since thymol blue proved unsatisfactory1*~. Poorer precision with this solvent can bc attributed to the predominance of benzene in the titrant, which intcrfcrcs with the action of azo violet.

I

I

40

NOKMALITY _.-_-_.--

I

60

01:

..I__.........

LITHIUbl

- ..__ -_.-,.

___.__. -_ .__.__. *.__.

t

,

80 100 % Neutwlitatian

. -_

~lIS’PIIO.SIDIS,

.,....___

50

120

_._-.,__...

_.

_.._.I__.._.. ..- .

scJI.U’I’Ios . .._

r\,

______

_

1)s. _...

SL!LI”A.\lIC

_,

_ ,__.. - .._

IXrnctlivl ‘I’l1y11101 Iilue

form;rIll~~lc

IXrncthyl sulfositlc

‘rllplllol

Am

Ethylcnwlinminc

_______

-__-_

I3lllC

‘1’11y11101 IllUC

~z-13I1t~li~llliflc

. ..__._-

Violet __-----..-

ACIIJ _.-.

,. .

.

100 % Neutralization

_._.

IN

.I

I5ASIC

,.

. _.._..

.

”

.

150

S0I.V1SS’fS _..-_.._-

._

.. __..___.._

8

o.r3tG

o.ooalH

0.000~~

x

0*‘315 0.13lC

oJJocY37

V.0003~~ o.ofm3 I

x

H .---.__-__-__-..---..-

0.1315

-_..

O.OO~l~
_.._.. _‘.______..

. ..._ _

__

0.000~0 ..

.._..__.. - __.._._

- __._..._._

A comparison of the potcntiomctric titrations of sulfamic acicl in the four basic solvents is illustrated in Fig. 3. A large diffcrcnce in the height of the potential break is evident with dimethyl formamide and dimcthyl sulfoxidc both of which surpass the other two. All of the solvents for this particular test were used, as rcccived, without Referewcs

p. 214

51. 51. cIw3,

210 further basic

A major easily

‘1’1~ solvcntswcrc

purification. hcforc

titration

rcquircmcnt

clctcctccl.

is sl~~wn

about

cncl-point,

A

the

for

plot of cllY/clV

in

l;ig.

usctl

4. Since

can

tlwn

adjusted method

st~mclard

to clctcrminc

the end-point

71s. V

simply

neutralization

;L volumetric

‘1’1~ mcthocl

titrations tlw

using

the can

VOL.

hf. CISI:OLA

is that

tlw

titration lw. tlcfincd

so that clcscrihccl

the

the

wcrc

slightly

above.

cquivalcnce

cncl-point for alqwars curve bv

they

21 (1959)

maximal

point

lx

the potcntiomctric to 1x2 symmetrical value

of dl:‘/clV.

lx

titration. 4.94

ml

1400-

1200-

IOOO-

800

-

600

-

400

-

si 2

20

I

40

I

60

I

I

I

80 100 120 % Neutralization

I;ig. 3. I'oti:nLicmctric LiLmtic311 of SIllfir1nic iICiCl in 1r)ttr I)XSiC Sc~l\*clltS. S~~IVcllts: curw :\ -tliincthyl forin~rmitlc; c11r\*c' . I3 -tlinicLhv1 sulfuxitlc; curve C: --.ctl1~lci~ctlia111'inc; curve I> -- rbhtpkrininc:. St;~ntl:~rcl: .18.6 iilK si1lk~niic ilCid. '1'iLri~tlt:0. lo31 A' lithirin1 nictlic~sitlc. I~lcctrotlc system: l~l;rLi1ii111~-111c~clifi~~l Ci~lOllll_*l.

‘I’hc

titration

curve

for

tlic

St~UKl~~rdiZntion

200-

TitrantCml)

I-

l’i&. .I. hlcll1otl fclr tiic tlctcction c,f tl1c cnrl-point. lllcctrcltlc systcni: l>lntin11nltlinicthyl fornimnitlc. c~~l~mlcl. S~llvcllt: Staiitl;~r~l : .IS.(> riig sr1lf;lmic ilcitl.'I'itrnnt: o.cqg8 A' litl1ir1111 iiictl~c~sitlc.

Of lithium

mcthosiclc

71s. sulfamic

acid

shown in Fig. 5 is intcrcsting in so far as the concluctancc lcvcls off after the end-point is rcaclwd, remaining ~nclinng:ccl as mow titrant is aclclccl. Curves of this type wcrc rcportccl by IL\l~\-o-rr lG for both cli-7t-butylnminc iLIlC1 tricthylaminc, liowcvcr, and are apparently characteristic of anhydrous systems for titrations in basic solvents. Tl~se titrations wcrc wry tedious clue to the erratic bclx~vior of the clectrodcs. The reproducibility of results rangccl from 3 to cj”k,. Concluctornctric titrations provccl very scnsitivc to Clli~IlgCS in acidity and a sulIh!fcYotcrs p. 2r.J

VOL.

21 (x959)

STrWDARD

IS

XOXAQUEOUS

TITIZIJIETRY

211

famic acid solution in glacial acetic acid could be titrcrtecl with lxrchloric acid in tho same solvent. This titration curve is shown in Fig. 6. l~~~~rocl~i~ibilit~~in acid mocliunn was incrcascd over that reported above and ranged from 2 to qy.6.

Effect of wcrtcr The delctcrious cffccts of water upon nonaclucous solvent titrations in gcncral hsx*e been rcportcd by many authors, xncl most basic sol\*ctnts, including climctlq~l

formrrmidc, hrtvc been known to bc sensitive to moisttlrc. fit(t~%‘” hacl rcportod tflc inability of the indicator to function prolxzrly in ;L climcth~I formarnidc system tvh~n Ixrformcd, both I*/* of water is osccodetf. -4 series of titmtions wc!rc subsqucntly visually and potentionietrically, in or&r to determine the csact cffcct as the water content in the sclvcnt wils incrcnsccl to ST&,.l’hc results for visual titrations arc listccl in Table III. Poorer precision is attril>utccl to the slowetl rcsponsc of the indicator as the water content is raised. Also noticeable is the change in the normality of the: titrant, Apparently this is clue to the hydrolysis of the climcthyl formamidc splitting off forinic acidlo. The effect of water on a potcntiomctric titrations is shown in Fig. 7. The steep potential break exhibited in an anhydrous system gives way to a gradtlal slope as the water content was raised. Also evident is the noticcahlc depreciation of the height of the potential break at the end-point. It’efcl%ricr*s p, 2r.j

212

In orclcr to asccrtnin the tlclctcrious cffcctsof c~~rhm cliosiclc unclcr ordinary lnboratory conclitions, x+md titrations wcrc lxrfornicd after tllc titration solution was pcmnittccl to stand cslmsccl to tllc air for intcrvnls from 5 to 25 min. ‘1’1~ titrations wcrc: then lxx-lormccl quickly, with nmgnctic stirring, at the close of the slxcificcl tinic interval, and the change in the nortnnlity of the titrnnt was notccl. In the two scrics of orpcrimcnts the grcatcst clcviation up to 25 min cslmsurc time was 5 parts per 1000, as seen in ‘l’ablc IV, given on the basis of deviation from tlic clctcnninccl normality of tlic bnsc. From tlic results in l’ablc IV, it sccnx that tlic rate of absorption of carbon clioside 12cfcreuccs

p.

224

-1’.4131.1s IV

I:FFBCT OF

,~TMOSl’lf~~f,1(IC --

--.

__.._-_.l-___.

--

SOLU’FIOSS _-___-

.

..__-

C..%l~IiOS131OSI131~ 01:

__..__ -

.___._.

_.._

_.._-

-.-

UPOS

hfISTfiOSfDE _.--- - ---_--

LlTltIUJl

-

..-^.

Tf.II:

-..

-.--

0

G

0.

roS2

0.0002

5

;z

0.

tosr

0.000

I

10

‘2

0.

to81

0.000

I

‘5

2

0.

I

‘2 0

‘2

0.

IOSl

0.000

25

I

0.

loss

0.0000

_.-.....--.. - ____-___-----._

-

OH.1

.~..

_..

..-.

I

OF

.‘,’

0.1

,\Cfl)

.I.._..,L ,,...,.______

--_

0

.ooo.?

O.lCJCJS 0. I or)6 0. I ogG

0

.ooo.#

0

.oooG .oooG

0.

0.000.~

0.

0.0002

- -------

S’I?ASDhHl>t%,Sl’lOS

US. f4l’.N%OfC -,--__ _..-_.. __-._____

0.I

I 103

0

IO)7 103

.- .- - - - _- -..- --

0.000

I

.-..-.I_ .._.~

is cluitc slow, even under tlwsc cstrcme conditions. Apparently it can be cnncludcd that climcthyl formamidc can lx safely used in tlw xvcragc laboratory with merely simple lxwautions taken to guard against ciu%on clioxidc uptake. Ikforc performing the ~~ot~ntiom~tric titrations, tlw clcctrodcs wxt: ptrntittccl to stand in tlw solution for at lcnst IO min. It was founcl that this ten-minute period enabled the system to approach ~~l~lili~~ri~lsnand rcgistcr a stcncly reading on the mctcr. The titrant was aclclcrl in small incrcmcnts and the electrodes again l~~rsilittccl to ccluilibrntc before tltc rcacling was rccordccl. When this time was allowccl at the start of the titrations, cclulibrium w;~s a&icvcxl witlkin no to 60 stx upon the i~tlditioil of cacli incremt:nt of titrant up to the stoicliiomctric point. Oncct tllis point was al+ proachccl, longer intcrxxls wc’rc: rwluirccl for the system to uquilihratc. One of the great disaclvantagcs of the platinum clectrotlc can hc swn here. Howcwr, tllc final result gnw ;I large potcntiomctric break ant1 S~~lll~\Vllilt offset this difficulty. At first it was thought l>ossiblc that tllc amount of water actually lxcscnt in tlw solvent could lx qunntitativcly estimatctl from the incrcnsc in tlic volume of titrant rccluircd for neutralization in a climcthyl formnmitlc system. ‘l’hcre was a definite shifting of the titration cwVC: wit11 t’hc incrcasc of watc!r, c~lclccl cspcrimentally, but no rcliablc quantiti1tiVc information could bc cstablislwcl at this point in tlw invcstigation. Also, tllc clcctrodc system used for thcsc titrations approachccl ccluilibriurn more slowly as the wntcr content was increased, wlkll made the lxoccclurc tedious. This application, in view of tlicsc difficulties, was abantlonccl since the Karl Fischer titration is easier to perform, citlrcr visually or l~otcntiomctricnlly. Tlic following IlX92lliUliS~l CilIl be l~rolxw2cl for titrations of sulfamic acid in climcthyl formamide : I1 .i” I

In conclusion, tllc cxpcrimcntal behavior rcportcd in this paper justifies the foliowing assumptions: I. Sulfamic ncicl can be titrated by both visual und potcntiomctric means with ;L i~cferrwes p. arj

strong base, lithium mcthoxidc, in several basic solvents. It can also bc titrated with ;I strong xid, pcrchloric acid, in an acidic solvent by con’ductomctric means, although the mcthocl is ncithcr practical nor prccisc. 2. It is possible to use sulfamic acid as a primary standard in basic solvents for the stancl:~rcli;r,ation of lithium mcthoxidc. When clissolvcct in climcthyl formamide, it stunclurclixccl tllis bust with a precision of 0.27’)$+ Precision in otllcr basic solvents rnngcd from 5.3 to 0.5’s,. Sulfamic acid can 1x2used for titrations in n-htitylaminc without the formation of gels or prccipitatcs which interfere wit11 tlic titration. ACI
%uChors wish to thank Doctor Jorrrz ccrniq clcctrotlc systems in lxrsic mcdin. ‘J‘he

C. RYAN

fr)r liis Mpful

su~~estionk con-