65
V O L U M E 2 2 , N O . 1, J A N U A R Y 1 9 5 0 The interference of copper, iron, and other cations in the iodometric determination of arsenic has been eliminated by the utilization of a sulfonic acid exchanger in a procedure devised by Odencrantz and Rieman (19). Thr proredure involves the solution of the sample, oxidation t’othe quinqurvalent state, evaporation, re-solution, and passage through the cation exchanger in the hydrogen form. The arsenic is then determined iodometrically, using st,andard thiosulfat,c for the titrat,ion of the liberated iodine. This met,hod eliminates the distillation step recommended by the Association of Official hgricultural (‘hemists. This procedure is analogous to that developed by Helrich and Rirman (8) for t,he det.c)rmination of phosphorus pentoside in apatite. I n the determination of copper, iron, aluminum, calcium, arid magnesium, polybasic carboxylic acids such as oxalic and tartaric acids interfere because of their complexing and sequestering activity. Their removal usually requires a lmgthy oxidation with nitric wid or aqua regia. In order to simplify the removal of thcse intcbrfering anions, Iclement and Dmptruk (10) have suggested thr. use' of an anion exchanger in t’he rhloridr form. Sulfate trace impurities prescxnt in gelatin used in thcs nrphelometric analysis of sulfates have been removed by Honda (9) with the aid of an anion cwhange resin. I t is probable that the gelatin, starch, and gun1 arabic used in many other trace analyses can be similarly purified by ion exchange. I n order to eliminate the interference of calcium and iron rapidly in the colorimetric analysis of silica traces, Lagerstrom, Samuelson, and 8nholandw (15 ) rmployed a sulfonic acid exchanger in the hydrogrri form.
cerous ion and the cation exvharigt. resin in the presencta of tht. foregoing anions. ELECTROR EXCHANGE RESINS
Although no analytical methods have made use of the “elertron exchange” resins of Cassidy ( 2 ) , the successful synthesis of polyvinylhvdroquinone by Cassidy and his students (29) may lead to a new analytical tool similar to the Jones zinc reductor or the silver modification of this reductor. Cassidv and his students have found resins of this type to form a reversihk oxidation-reduction system for the ceric-cerous and bromine-bromide equilibria. Although far from being perfected, these resins map bc of considrrable analytical significance in the future. LITERATURE CITED
Blumer, &I.,Ezperientia, IV, 351 (1948). Cassidy, H. G., J . A m . C‘hem. Soc., 71,402 (1949). Cohn, W. E., Ibid., p. 2275. Cohn, W ,E., personal communication. Cohn, W.E., Science, 109, 377 (1948). (6) Cohn, W. E., Parker, G . W., and Tonipkins, E. l < . ,.VuclroLcs. 3, No. 5 , 22 (1948). (7) Connick, R. E., and Mayer, Y. W., Abstracts, 116th hleeting AMER.CHEM.Soc., Atlantic (‘itg, p. 18P, 1949. (8) Helrich, K., and Rierilan, R.. 1x11.Ewn. CHEM.,.ix\t.. t.:~)., 19,
[l) (2) (3) (4) (5)
651 (1947). (9) (10) (11) (12)
Honda, >I., J . Chidm. .5’oc. J a p u n , 70, 52 (1949). Klement. R., and Dmytruk, R., Z . anal. Chem., 128, 106 (lY48). Ibid., p. 109. Kraus, K . A , arid Moore. 0. E.. .T. A m . f‘hpm. Sm-,,71, 1283 (1949).
DETERMINATIOh OF CO\CENTRATIOh
(13) Ibid., in press.
The drtermination of total electrolytr concentrations by ion excahange has become of considerable interest. Because it is possible to convert a neutral solution of an elec+rolyte complrtely into the free acid on passage through a rolumri of a sulfonic acid exchangu in the hvdrogen form, severnl investigators have studied this method for various c,lectrolyte mixtures. Blumer (1) has eniployed this method for ascertaining the total concentrationof natural tvater supplies and Tolliday, Thompson, and Forman ( 2 5 ) h a w adaptcd this proccdure to chroinr tan liquors. I)ETER\IIYATIOY OF EQUILIBRIUM COYSTANTS A-1) ACTIVITY COEFFICIEYTS
(‘ontinuing the work of Vanselow (30) and Schubert (22)on thr. u5e of ion exchange in equilibrium constant and activity coefficient measurements, ?*layer and Schm-artz (17) and Connick and Mayer ( 7 ) have determined the relative activity coefficients of (’eroussalts and the association betiwen cerous ions and the perchlorate, nitrate, sulfate, iodide, bromide, fluoride, sulfite, pho+ phatc, and pyrophosphate anions. The technique involves thcx rncrtwremrnt of thc comparative ion vxcahnngr equilibrium of the
(14) Kunin, R., . ~ K A L . CHI-M.,21, 87 (l94Y). (15) Lagerstrom, O., Samuelson. O., and Srholauder. X.. Swrish I’ny perstidn., 108, 439 (1948). (16) Linqvist, I., Acta Chrm. Srand., 2, 38 (1948). (17) Mayer, S. W., and Schwartz. S. D., Abstratts, 116th Meeting AM. CHEJI.Soc., p. lYP, 1949. (18) Nachod, F., “Inn Exrhange,” Sew Tork, Academic: Preas. 1949. (19) Odencrantz, J. T., and Rieman, W., Abstracts, 116th Meeting h f . C H E Y . S O C . , p. 15B, 1949. (20) Partridge, S.M.,Ch~mistrgKS Industry, 1949, No. 1, 12. (21) Kauen, H. >I., and Felix, K., 2. physiol. Chem., 283, 139 (1’448). f.22) Schubert, J., J . Phys. Colloid Chem., 52, 340 (1948). (23) Steacie, E. W. R., and Calnbron, .1., Research, 2, 225 (1949). 124) Street, I Red
Yellow
4.8-6.6
Red
Yelloiv
4.2-6 .O
\Teak orange
Yellow
4.0-5 8
......
......
Red
Ked
dianlinoaao!)enzene
,j 4 ' - l I < ~ t l l c ~ x y - 2 , 4 -
diaminnaeohenzene
6 4'-lIethusy-L'.4dian1ino-.5-rnrt tiyl. azohmzene
8
2 ' - l l r t l i o x ~-2.4diaminoazobrnzenr
$4
3'-31etirosv-2,4dianiinoazohenzene
Orange-yelloir-
, , ,
,
,
...
. I . . . . . .
15
4'-E:thoss-3-calbonic acid-4-osyazohenzrrit
16
4'-Ethos~-3-"xy-2,4diaminoazobrnarnr
17
Phenetole (4-azo-4)-1naphthylairiine
COOH
,..
...
Violet. in 30% His04 blue Violet
I .
Yellon.
6.0-8 .O
Red
Light yellon.
Yellow
.....
Red
Light yellow
Yellow
i .O-9.0
Red
Light yellon.
Yellow
.....
VlOlPt
..
,
Yellow
18 Phenetole (&azn-4)-1-
naphthol
(Continired on nest p a g e ) .__
I . . . .
Light yellow
.......
____ .. _ _ _ _
...
Orange
.. . , ,
Light yellow
Red
2.2-4.0
Light yellow
Red
7.2-9.0
Light, yeJow
Ked
Violcr
ANALYTICAL CHEMISTRY
68 Table I.
h-0.
Acid, pH 2
Constitution
Same
Continued Color -4lkaline
19 4’-Ethoxy-2,4-diamino3-methylazobenzen?
Red
20
4’-Ethoxy-2,4diamino-6-methylazobenzene
....
21
J’-Ethoxy-Z’-methyl2,4-diaminoazobenzene
29
4‘-Ethoxy-2’,6‘dimethyl-2,4diaminoazobenzene
23
4’-Ethoxy-2’-bromo2,4-diaminoazobenzene
24
4‘-Ethoxy-2’,6’dibromo-2,4diaminoazobenzene
25
4’-Oxy-3’,,~,’-dibro1iio2.4-diamlnoazobenzene
Color Change Interval pH
.....
Oxidation-Reduction Property, Color Reduced after Oxidation with Oxidized Ce(IV) BrOsLight yellow
....
.......
....
.....
.......
....
.....
.......
Red
. . . .
Red
...
..
Br
........
”1
....
..
.......
,
.......
...
H O ~ S = X ~ ) U H ~ ‘\
Br
28
4’-Ethoxy-2,4-diamino,?-bromoazobenzene
/SH2
..
Weak yellow
Red
Red
Red
C z H s O O S = Y C > r i H z Br
27
4‘-.4cetoxy-2,4rliaminoazobenzenr
....
.....
Weak yellow
Red
28
4’-Phenoxs-2,4diaminoazobenzene
....
.....
Weak yellow
Red
...
29
4’-Ethoxy-2 4-diamino3.5-dibrorhoazobengene
....
.....
Weak yellow
Red
...
30
4’-Ethoxy-2.4-diamino3,&dimethylazobenzene
....
.
Weak yellow
Red
..,
.,
~
Table 11. Properties of Indicators riame 4-Hydroxy-3-methoxyp-nitrostyrene 1-(4-Hydroxy-3-methoxyphenyl)-Z-nitro1-propene 1-(4-Hvdroxs-3-methoxyphenyl)-2-nitro1-butene 1-(4-Hydroxy-3-methoxy)-d-nitrostilbene
Meltina Point, C.
Color Change Inter7 dl pH
pKr
I
169
6.1-8 1
7.6
1.3
I1
103
6.8-8.8
8.2
7.2
6 8-8.7
8.1
11.8
6.4-8.4
7.7
5.2
Dewnation
I11 IV
80.5 125
Kate of Fading in
0 1 .V N a O H ,
A h .
1 1 , ~
of ferrous tri-(5,6-dimethyl-l,lO-phenanthroline)called dimethyl ferroin. A 0.01 M solution is prepared by reaction of 0.03 mole of the base n i t h 0.01 mole of ferrous solution. I n 1 N acid the oxidation potential is 0.97 volt. The indicator gives a sharp end point in the titration of frrrous iron with dichromate in 1 to 2 F (formal)
hydrochloric or sulfuric acid. The color change is from red to greenish and completely reversible. qCID-BASE INDICATORS
The compound 4-hydroxy-3-methoxy-p-nitrostyrene (I) was recommended in 1925 by hl. G. S. Rao et al., as acid-base indicator, but no quantitative data on its properties were given. Stewart and Clark (7) prepared and investigated compound I and some of its homologs by condensing vanillin with the appropriate nitroparaffin. H3CO NO* \
HO-~-CH=C-R I. R = H 11. R = CHs
/
V O L U M E 22, NO. 1, J A N U A R Y 1 9 5 0 In extremely dilute solutions the color change is from faint yellow (acid) to pink (alkaline) for I and IV and from faint yellow to ambar for I1 and 111. I n strongly alkaline medium the color fadrs, but the sluggishness of this color change renders it useless f o r indicator purposcs. The properties of the compounds are summarized in Table TI. The mechanism of the color change is given by:
69
Colorless Stock solutions (0.1%) in alcohol are prepared. It is not stated whether any of the indicat.ors have advantages over phenol red or other Clark and Lubs indicators which have about the same color change interval. LITERATURE CITED
Faint yellom-
+
OH-
+
Pink or amtwt
(1) Belcher, It.. Anal. Chim. Acta, 3, 578 (1949) (2) Raykhinstein, 2. G., and Kocherigina. T. V., J . Anal. Chem. (Russia), 2, 173 (1947). (3) Schulek, E., Z. anal. Chem., 102, 111 (1935). (4) Schulek, E.. and Rozsa. P., Ibid., 115, 185 (1939). (5) Schulek, E., and Somogyi, Z., Ibid., 128, 398 (1948). (6) Smith, G. F., and Brandt, IV. M., A h a CHEM., ~. 21, 948 (1949).
(7) Stewart, R., and Clark, R. H., Can. J . Research, B26,7 (1948). (8) Usel. F. L., Casopis Ceskdho LQkdrnictva, 15, 143 (1935). RECEIVEDS o v e m b e r 14, 1949.
FLUOROMETRIC ANALYSIS CHARLES E. WHITE, University of M a r y h n d , College Park, M d .
A
LTHOUGH this review is concerned primarily with the application of fluorescence to analytical problems, it is worth while to call attention to a book on fluorescence and phosphorescence by Pringsheim ( 5 7 ) . This is a much enlarged and revised edition of the author’s previous book on luminescence. The analyst \Till find of particular interest the discussion on the theory of fluorescence, and the sections on the fluorescence of organic compounds and the luminescence of pure inorganic compounds. The Russian Academy of Science has published a book on luminescence analysis, edited by Konstantinova-Shlezinger (39). Because this is entirely in Russian, it will find but little use in America until a translation appears. This same author has given a short review on fluorescence analysis (38). Feigl(22) devotes Chapter XI1 of his book on the “Chemistry of Specific, Selective and Sensitive Reactions” to the analytical use of fluorescence effects. This is so brief that many applications are merely named and much recent work is not included. In a new book on “Methods of Quantitative Analysis,” Milton and Katers ( 4 8 ) give a short discussion of fluorometric analysis with directions for the analysis of some few elements. Unfortunately, their references on this subject, except in one case, do not go beyond 1943. A critical revien. of fluorescence microscop\- has been given by Haniperl(29). APPARATUS
In a similar review last year (?I), the 360 B.L. phosphor lamps were mentioned as a new source of ultraviolet radiation for fluorometric work. These have now been improved to give over twice the ultraviolet output of the earlier models and the maximum is now at about 3500 A,, whereas the former was a t 3600 A. Curves giving a comparison of these lamps have been published in a bulletin of the Sylvania corporation (69). Analysts using the Klett fluorometer will be interested in an article by Slater and Morel1 (67) in which are given many suggestions on the use of this instrument, especially with reference to its use in determining thiamine and riboflavin. The use of the Pfaltz and Bauer instrument has been smplified by a test tube adapter which has been described by Durst and Lewis ( 2 1 ) and Myers (60). In spite of the efforts of commercial manufacturers, many
analysts prefer to build their own fluorometers. Price ( 5 6 ) and others, in a report from the Atomic Energy Commission, describe an instrument which they have designed to determine uranium by the fluorescence of the uranium-sodium fluoride melt. Their present instrument is of simple design, using a photomultiplier tube. I t is sensitive to 10-11 gram of uranium and the authors indicate that a still more desirable instrument will be described in a forthcoming publication. A simply constructed photoelectric colorimeter and fluoromrter is described by XcGillivray ( 4 5 ) . For photographing the fluorescence spectrum, Scheminsky ( 6 4 ) uses a hand spectroscope and a Contax camera, and reports excellent results. Fluorescence microscopy has many applications and a simple device including types of filters for this purpose is described by Zamkov (72). INORGANIC APPLICATIOh S
An interesting technique for the identification of the cations by using paper chromatography in conjunction with fluorescence has been reported by Pollard ( 5 5 ) and his eo-workers. The cations are dissolved in a solvent consisting of water, butanol, acetic acid, and acetoacetic acid ester, or other appropriate mixtures. This is dropped on Whatman KO.1 filter paper, so as to give spots about 1.3 em. in diameter and 4 em. apart. The paper is then sprayed with morin, oxine, etc., and observed under ultraviolet light. Twenty-four cations can he immediately detected by this procedure. The quantitative determination of oxygen (40)in quantities of 0.01 to 20 p.p.m. can be accomplished by permitting it to oxidize leucofluorescein to fluorescein. Stable solutions of the reagent are prepared by reducing fluorescein with sodium amalgam and storing it under a light petroleum fraction. As little as 1 X lo-” mole of oxygen (33)can be detected by its effect on trypaflavin adsorbed on silica gel. Oxygen destroys the orange fluorescence of this compound and a greenish hue appears. Several references to the analysis of beryllium in rocks were reported in this review last year. Sandell (63) has made some revision of his method in which morin is used as the reagent and shows that as small an amount as 0.05 microgram of beryllium can be identified. Granite containing as low 3 p.p.m., was analyzed successfully.
=
