terval... Z8.m tinie \vas defined a. tw. minutes niter the adtiition oi sodiuni lauryl wlintc. Thv nioet tlrartic changes ovcurretl n-ithin the first 10 minute:. Fry the period 10 t o 40 minute- inriiisiw. the logarithm Of tile per cent transmittanre is linesr with r r y e c t tn time antl depentlent upoi! t lit, voncentration of sodium lauryl sulfati.. To prevent the transmittance re:trling iron: increasing by more than 0 . 5 5 . nieasure-
Table I.
Influence of Available Chlorine Level on Transmittance
~ ~ 0 l l ~oi1 1
Soditin; Laur? ! Srilfats MnioIt-5 Litei
210
--
86.50
24 7 4
62.7'5 .io i 5 .&?,25
,I,
li 4 9 48 61 53 74 "2
240
__
0 0 1" 3; ? J ;
;\railable C1 Level, P.P.\I.
__
3 9 . @G
32.00 2 i . 15
36.00 :35.00
330
74.00 59.00
8i.50 72.50 58.00
80.X i
46.d 3 i . 5030.50 26.25
46.00 3i.W 29.013; 'L3.25
- a3.00
83.45 76.10 6 2 73 48 00
.El
3Ou
2i0
-1r.cT T of Duplicates
.\nalyais of Variance of the Log C; T from 5 0 to 330 Degrees Sum of Mean of Squares Squares >owre 01 Variance Freedom x 1oc x 106 .ivail:ibie chlonne (-4) -7 4,130 2.065 Concentration of sodium iaun-1 sulfate ( B ) 6 1.425,TOO 23;. 616 (;Ix B i 1" 151 1,810 672 Linear ivsponze to ( A X B ) I 6 2 1,138 103 Othsr reiponGe to (-1 X Bj l! Error "1 62 1.305 Totnl
41
i1.25
56.25 44.10 35.90 29.80 2.90
P.P.M. \'ariance Ratio 33 . 3 1
Prob al)ilit>-* V.S.
V.8.
:3a32,32 2.44 10 84 1.66
1-5c15
S.S.
1 ,4:3'2,945
Liiicar reprei+ion coc.fficient = -0.ooc)n883 log c-i T per p.p.ni. C1 at i 4 . Z pniolee per liter: (I
V.S.. \-c.r>. aignificant:
S.S..not significant.
Table 11.
Effect of Variables upon Color Developed in Test R;ingr
1-.1 rialJit .1v:til:tlilt. chloriiir
Investigated 210-:3:30 p.p.ni.
Stai)iiity oi wlorrtl conip1t.s
0-XI niin.
Time lapst. between addition of o-tolidine and sodium lauryl
0-15 niin.
Significant Sourres of I-arianre (1C,C Level .\railahle chlorine, sodium lauryi sulfate. linear interaction response Time. sodium lauryl mifate, linear interaction reep0n.w Linear time response. sodium lauryl sulf:itr 1
nient should Iw niatle b e t w e n 10 antl 2.) niinutrs. after the atltlition of the siKiiuni law!-! wlt'a tr., The influenw of the tinit1 iapee bet w w the atltlitions of o-tolirlinr antl miiiini lauryi PulCste a t seven different concentrations \vas tletcmninet! for tinir intervals of 0. 5 . 10. anti 1.5 minute.: nith zpro tinir tlefineti ae i iiiiniitr~after tlir addition of the o-toiidinr .soiutioii. The results intlivatetl that this tinir ii!ten-ai is ver\- importan? : the ~ p s p o n sis~ ~ linear with tinie and the regression cwfficicnt is indepentient of the concentration of sodium lauryl sulfate. For :i deviation of +0.5yc tranmiittancr. :t time deviation of 1 minute is permi+ sihie. For rel)roducihilit?-. a stanciarti time l a p of 2 minutes from the tinit. of addition of the o--tolidine t o the tinie of atlrlition of the sodium lauryl sulfa!? is reconimendeti. To detrrniine the effect of various voncentrations of o-tolidine. solutions coli.taining 1.5. 1.0. and 0.5 grani of otolidine dihylrochlorirlc per liter ::i lOYc hydrochloric acid were prepare(!. Two niillilitere of each soiution wen: used in the tle\-elopnient of the t\.pics! color and the per cent transniittaiirc for various concentrations of sotiiun; lauryl sulfate \vas measurrti. The r+ suits indicate that au 0-tolidine concentration of 1.0 grani per liter is adequate for a niasimuni sodium IaurJ-1 sulfstv concentration of i 4 . Z p M . Though tliP of variance shon-e that the concentration of o-tolidine and the interaction are significant. there are no apparent systematic changes in thr curia-
for Sodium Lauryl Sulfate
Regression Coefficient Linear Quadratic
\-a lu t Selected
cant roi YecessaryO a i ,Selected i-altie
10 niiii.
10 niin.
2 . 0 miii
f l . 0 niiii.
.. .
1 . 0 g. 'liter
f O . 0 3 g./liter
...
-1
sulfate
o-Tolidine concentration 0.5-2.0 g./liter pH of color development 2 . %.0
Time interval between &ILW mill addition of sodium hj-pochlorite and otolidine Normality of phosphate 2 . 6 4 O S huffel a
+Tolidine, sodium lauryl ... sulfate, interaction pH, sodium lauryl eulfate, linear interaction response, quadratic interaction response Iinear time response. + l . W x 10-3 sodium lauryl stilfate log c> T/miii. Sodium lauryl sulfate
..
Control necessary to restrict the error due to this source to &0.5yqtransmittance. of d u m lauryl sulfate (74.F~ pmolesfiter). Calculated for lowest roncentration of sodium lauryl sulfate (12.37 pmolea/literl.
* Calculated for highest concentration
1674
ANALYTICAL CHEMISTRY
3."
niin.
?2 5 niin.
S o control necess a y within the range investigated
3.50
L
p a r c ~ initti that obtained by thc atltli;ion of the rwgent in rapid succession. l'hr cffwt o f this phenonienon upon t,lic test x a s invrstigatd for timr iiitc~vals of 0, BO, and 120 minutes. The :in:ilysts of variances of tho data sho\vs :I signifi(*ant linrar dtyndcncac\ for tile* tiitit' factor. Ho\vovvr, a variatioii ot' r0.3$; t,ransmittance results only after it time laps(, of 22.5 minutes. This long a n i n t ? r \ d s thcrefore. does not c*aust' scbrious twor. To tlrtcmiine the dcycndrncy of thc c d o r d(~vdoprdupon the normality :)i thc phosphatc buffer! 2, 3. and 4 S phosphatr tiuffvrs \Cere prepared so 3 s to :\+id :i pH of 3.0 for color devr1ol)niont. Statistical analysis of the resuits in(ii(*ut(isthat, when buffers of tiortiiaiitics of 2 to -i:djusted to givc a filial pH of 3.0 :ire uscd, thcre arc no significa:int tlifforc~ncc~ in the per ccnt transiiiitt:iii~~ of t h r soiutions.
0.4 0
%
0.30
.
a L. 0
0
0.20
0.10
0.00 480 500 520
540
560 580 600 620 Wavr
Iongth
660 680 700
640
(mp
Figure 1. Determination of wave length of absorption maximum for sodium lauryl sulfate-haloquinone complex Sodium lauryl sulfate, pM
I. 7 4 . 2 2 II. 6 1 . 8 5 111. 49. 48
turv ant1 slope' with changes in tlir coii:w~tration of sodium lauryl sulfate. I.nder ttic conditions uscd, an orror i i i o-tolidinv conccntration of 0.03 grain per 1itt.r \\-auld not result in a differencc in ptxr w n t transniittancc of greatw T,han *0.5%. X w distribution of reaction products Iwtwcn t h e haloquinone and the mcrii!uinonc, for th(, action of sodium hypo.!ilorite upon o-tolidine is dcpcndcnt ~!i)otithc pH of the systrm. This, in turn, influrnws the intensity of the y t . p I c color devrloped when the sodium h r y l sulfate is added tu the system. I.. ! L I study this relationship, phospliatc' buffers wcre adjusted so 3s to ;:ie~d p H values for color deveiol)mc~nt of 2.5, 3.0; 3.5. and 4.0. The r t w i t s d m i n e d according to the usual design Ix!icatc, t.hat -the final pH of tho liufT(sr is R critical factor for the drvdopment 8)f tjhe typical purple color. .iG and hilyond a final pH of 4.0, the coior formed is too unstable for practical i;irasurcments because of fading a i d ::liould riot be considered. It is thought :!:at under these conditions the haloilainone-surfactant complex is not, i o r i n c d becwise of the rapid formation of L !,iuc: unreactive nieriquinonc. as intli,.:itod by the independenre, of thc intcbn.;it!. of the color with rrlspwt to con,*cntr:ttion of sodium iauryl sulfate. .! final p H value of 3.0 appears to be the .nost suitable of those invcbstigated on the basis of intensity and stability of mior developed. The response in the togarithm of the per rent transmittance for the various finai pH levels is a curvilinear one and greatest a t the lowest
IV. V. VI.
37.1 1 24.74 12.37
c~)iicc~iitr:itionof 12.37 priiolcs y r liter oi sodium iaiir>.l sulfat,c,. .it pH 3.0, a \xriatioii of *0.05 will c ~ i u s oa n wror oi &Io.3G/;. in transniittunw :it this concciitratioii Ivvrl indicating that s very c.ai.c~fii1iwntrol of pH is ricwss:q. If tiit, sodium tiypoc~hloritr~solution is atltl(.tl to t,ilt. buffvr solution and the iilixturtx is allo\z.cd to stmtl for a considerable tinw hefort, tlic, addition of the o-tolidine solution. :i slightly h i g h per cent transniittancc rrsults when com-
'Table 111.
Recovesy of Sodium Lauryl Sulfate
Barteriai Suspension 172 x 109 C'ells/Ml. ), 311.
Period of Boiling, Min.
owr kshestoa
e
i0
1,:ffcct of Boiling No
28 30
N O N O
0 0
Filtercd
Sotiiiim 1,aiin I Sulfate, pmolt- I [,iter ._____
.iddt&T iii
lierovered
.\lkalinc~lltdium 47 63 -&ti :39 18 39 46.39 46 :30 45.46
Effect of Filtration Only
0
S O
77 .:12
