COLORIMETRY OF ORTHOPHOSPHATE 117

polymetaphosphatc is partly overcome by storing the dcvclopcd color for about go min. Low concentrations of copper and mckcl and hrghcr concentrations of iron(II1) remove either partmlly or complctcly the mhlbitron due to polymctaphosphates. None of the metaphosphates mterfercs in the estrmatron of orthophosphate by the rsobutanol cxtractron method of BERENBLUM AND CHAIN

R&SUM I%

Unc dtudc a dtc cffectuee sur Ic dosage colorlmbtriquc dc l’orthophosphatc cn presence dcs phosphates condcnsbs, par la mdthodc dc LOWRY-LODEZ. On a cxammd dgalcmcnt l’mflucncc dc tracts de cmvre ct d’autrcs catrons sur le dosage

ZUSAMMENPASSUNG

Der st(irendc Emfluss von Polyphosphatcn auf di‘e c&foi-fmcfiischc Bcstlmmung der Orthophos- phatc nach LOWRY-LOPEZ kann durch klcmc Mcngcn Kupfcr, Nrckcl odcr Elscn(III) wertgchcnd ausgcschaltct wcrden.

EEFERENCES

1 A C CHATTERJI, H N UHAHCAVA, I<. I< mWAR1 AND P S KHISHNAN, .~YC/I Bzochettr. Bzopkys . in the press

2 C.H FISKE AND Y SUBBAROW,J. B~ol. Chcrn ,G6 (rgas) 375 2 J. B. SUMNER,SC~C~IC~, roo(rg44) 413 4 0 H LOWRY AND J A LOPEZ, J. Uaol Chewa., IGZ (1946) 421.

.*

G J. BERENBLUM AND E. CHAIN, Utochettr. J., 32 (1938) zg5 0 M.M DAVIDSON-REYNOLDS, R. B.~~ARRUETO AND H.IM LEMON, Etrayttrolog~a, r7 (1954) 145. 7 H. WEIL-MALHCRBE, Baockctn J.,-55 (1953) 741. s J. J.PEELAND 13 C LOUCHMAN,SLOG/~B~~~ J .65(rg57) 709. 2 J. H BRUE%~Z+IKR AND B L O'DELL,J.BIOI C/rem ,21g(rgsG)z83.

Anal. Clbrm Acla,22 (x960) rrr-1x7

PY ROMELLITEIN INDICATORS

I. ACID-BASE INDICATORS CONTAINING FOUR CONDENSED

PHENOLIC GROUPS

JOHN A BISHOP

Newurk College of Engrneertng. Newark, N.J. (CJ S A )

(Received July rqth, xg5;9)

In xgoG SILBERRAD r-2 reported the preparation of dyes formed by condensation of phenol and of resorcinol with pyromellitic dianhydride to give materials which he suggested could be used as dyes with mordants.

While such compounds are possible indicators, since they resemble phenolphthal- ein and fluorescein in their structures, no attempt seems to have been made to use them as such since that time. The dianhydride structure should permit the prepara- tion of two very interesting groups of compounds, since it is possible to condense two or four phenolic groups. There is also the possibility of making “internally mixed’ indicators by condensing two different phenols with the dianhydride.

In preparing such compounds the author hasfouridthatit is much easier to obtain

Anal. Chrm, 14~~;,2l~(xg60),xx7--119

II8 J. A.BISHOP

clearly defined puie compounds containing four condensed phenolic groups and the present paper is concerned with them. More work is being done on the purification of compounds containing two condensed phenolic groups, and a report on this will bc presented later.

Fig. I. Structure of pyromcllltcln lncl .1cators.

Indicators containing four phenolic groups of the same kind may be prepared by the usual methods for making phenolphthalein and resorcinol. When S-hydroxy quinoline was used, it was necessary to precipitate the indicator at a pn of about 7 since it is soluble in both acids and bases, as was the case also with the condensatron product with dimcthyl aniline.

In testing these compounds for USC as indicators, a titration was carried out using a Fisher titrimeter, the PH range and color change being noted. Samples were pre- pared using buffers for use in determining the transmission minima using a Beckman spectrophotometer, Model B. These results are summarized m ‘Table I.

OPTICAL l’R01’13RTII’S OF 1’YROhlI:LI.l rl 1N INDICATORS (VISllILlS LICIIT)

I~%cnol LJhcnol Oxlnc Oxlnc

C-ClCal-I~oti 0-clclJH40~~ Rcsorcinol Rcsorclnol

P11c1101 Rcsorclnol

DiMcAnlllnc IIhMcAnlhnc

C-pinlc Y-Gr. (I) C-purple Ihnk-red

Pink-rctl

Y-l3lue (3)

IO 12 3- IO--II 5 g-10.9 Red al,ovc 8

Red above G (2)

4-5.6

5000 6400 and 3700 (Craw) 5750 4600-l”H 5 5000-dXw! pIi 8 4600~PH 5 4900-dJOVC pH 6 6200 (4)

I. Decrease in transmission to pn x1.5, then increase at pri 12. 2. Sudden brightness at pn 6 in visible light. 3, Sudden change at 'pH 4.5 going from acid to base. COa interferes in base to acid. 4. Pronounced decrease in transmission below 4500 A at all PH values. Since some of these compounds showed fluorescence under ultraviolet light, a

titration was carried out using the titrimeter along with a shielding arrangement so that the solution was exposed to ultraviolet light and shielded from daylight. Since it could be seen visually that the fluorescing indicators showed fluorescence to blue light, the maximum for the emitted fluorescent light was determined by a differential method using the Beckman. This consisted of determinin g the light

And. Ckrm. Acta, 22 (1960) x17-1x9 w

PYROMELLITEIN INDICATORS. I. 1x9

trcrmcnis~i~p twice by the method usually used with this instrument, except that on the first run d-blue filter was placed ahead of the sample cells (inclu~ng the water cell), and on the second run the same bIue filter was put after the sample cells. The difference was a measure of the amount of fluorescence. The method was checked using dichlorofluorescein. What is obtained is not an absolute measure of the fluo- rescence but simply the maximum of the fluoresced light. Results are shown in Table II.

TABLE II

FLUORESCENT PYROhtELLtTt%tN INDXCATOXS (2)

fi. Color chatrjie (1) pff.runge Emurwva marrmum -

Iiesorcrnol licsorcinol Y- 1:I. Cr. O.G--2 4go I’Ilcnnl I<esorctnol Y-I’1 Gr r 9-4 4go

x. Under near ultravrolet hght. 2 Tltc DrMeAmlinc and oxmc compounds also showed slight blue fluorescence from pzr f-t2

The data presented in this paper were obtained in dilute solution by titrating carbonate free NaOH with HCI, both solutions being about 0.1 N. The polyprotic nature of these indicators make it very probable that there will be pronounced salt effects, which are yet to be determined. The oxine condensation compounds arc of particular interest since they contain not only acid hydrogens but are capable of forming complexes through the nitrogen of the oxine. Particular attention will be paid to these compounds in future studies of salt effects.

ACKNOWLEDGEMENTS

The author wishes to acknowledge assistance in this project through a grant from the National Institutes of Health (PALS. Grant RG-5736), and also the’generosity of the E. I. DuPont de Nemours Co. in supplying him with pyromellitic dianhydride.

A scrics of rndrcators have been prcpared by condcnsmg pyromclhttc dranhydrrdc wrth varrous phenols. Color cluu-rgcs and pH ranges llavc bccti dctcrmmcd, both In v~s~blc light and in ultra- v:olct itght, for those rndtcators that fluoresce Of partrcular interest IS the mdrcator prepared using oxme as the pltenobc compound, smcc there IS a posszbrhty in tlus case of complex formation through tbc mtrogcns of the condcnscd oxmc groups

Unc s&rre d’mdrcateurs ant &t& prdpards par condcnsntron du clranbydrrdc pyromcllrtrquc avcc drvers ptirSnols Lcs pH de vinge et les clttwtgcmerttu de colorations ont bt6 d&urmrn&s.

ZUSAMMENFASSUNG

l>ie Kondcnsationsprodukte von Pyromclll~ure-dlanhydrltl mrt vcrschredcncn Pfmnolcn ergnen sic11 als Xndrkatoren. Die PH Wcrte der Umschlagspunktc und die FarbYnderungen wurdcn angcgeh-cn.

REFERENCES

’ 0. SILBERRAD, J. C%?tti. SOL, 89 (x906) 1787. 2 0. SILBERRAD. PYOC. G&n 'Sk, 22 ‘(1906) &3x.

a 0. SILBERRAD, Proc. Chstn. Sot,. 24 (190~) 705..