V O L U M E 2 4 , NO. 9, S E P T E M B E R 1 9 5 2 Table TI. Fuel Oil No.
4 6 7 8
9 10
11
1467
Reproducibility of Pyrrole Determinations
Fuel Oil Type Catalytic Catalytic Catalytic Virgin Catalytic Virgin Catalytic Thermal
Crude Source
(TCC) (FCC) (FCC)
W. Texas Ill. and Mid-Cont. Wyo. and Ill.
(FCC)
U‘. Texas
(TCC)
Ill. Ill. and Ky. Mich.
ni.
Pyrrole N, Weight % A B 0,0073 0.0073 0.0075 0,0077 0.0064 0.0067 0.0030 0.0025 0.0109 0.0098 0.0020
0.0268
0,0023 0.0244
0.0034
0.0029
reaction product. Carbazole and tetramethylpyrrole are csaniples of such materials. It is possible that not all alkylated pyrroles that have a hydrogen on a carbon atom of the pyrrole nucleus will react-e.g., Fischer and Orth ( 3 ) report that 2,3,5trimethylpyrrole will not give the Ehrlich color. LITERATURE C I T E D
(1) Chernoff, L. H., ANAL.CHEM.,12, 273 (1940). (2) Fischer, H., Beller, H., and Stern, A., Ber., 61, 1078 (1938). (3) Fischer, Hans, and Orth, H., “Die Chemie des Pyrrols,” gp. 8,27,
Leipeig, Akademische Verlagsgesellschaft, 1934.
This procedure has been used mainly for the determination of pyrroles in distillate fuels and has given satisfactory results on both virgin and cracked stocks. It has been used successfully on straight-run gasolines, but has given erratic results on cracked gasolines-Le., in some cases it has worked well, while in others the reproducibility has been poor. The procedure has not been applied to materials boiling above a temperature of 675” F. The variation in colors produced from various substituted pyrroles has been mentioned. Production of a color upon reaction with pdimethylaminobenzaldehyde occurs only with pyrroles having at least one hydrogen atom on a carbon atom in the pyrrole nuclwu-i.e., tetrasubstituted pyrroles will not give a colored
(4) Gilman, H., and Blatt, A. H., “Organic Syntheses,” Vol. 1, p. 214, New York, John Wiley & Sons, 1941. (5) Mapstone, G. E., Petroleum Refiner, 28,111 (October 1949). (6) Richter, F. P., Caesar, P. D., hfisel, S.L., and Offenhauer, R. D., paper presented at 121st Meeting. AM. CHEM.Soc., Milwaukee, Wis., iipril 1952. (7) Thompson, R. B , Chenicek, J. A., Druge, L. W., and Synion, Ted, I n d . Eng. Chem., 43, 935 (1951). (8) Van Meter, R., Bailey, C. W., Moore, R. T., Allbright, C. S., Jacobson, I. A., Jr., Hylton, V. M., and Ball, J. s., paper presented at 121st Meeting, AM CHEM.SOC., Milwaukee, Wis., .\pril
1952 RECEIVED for review February 6, 1952. Accepted June 19, 1952. Presented before the Division of Petroleum Chemistry a t the 121st Meeting of the AMERICAN CHEMICAL SOCIETY,Milwaukee, Wis.
Fluorometric Determination of Traces of Beryllium H. A. LAITINEN
AND
PEKKA KIVALO, University of Illinois, Urbana, Ill.
The present work was undertaken in an effort to simplify the procedure of Klemperer and Martin, which involves two quantitative coprecipitation steps requiring centrifugation of the phosphate precipitates. A study of the variables affecting the fluorescence readings of beryllium with purified morin was also deemed desirable. Phosphate is removed by precipitation as bismuth phosphate from nitric acid solution. Calcium, if present in large amounts, is partly removed as the sulfate. The heryllium may be gathered by precipitation with hydrous ferric oxide at pH 6 to 6.3, follow-ed by electrolytic removal of the iron at a mercury cathode. t Iternath ely, following the removal of phosphate, the solution may be electrolyzed and subjected to the acetylacetone extraction method of Toribara and Chen. By this combined method, beryllium may be determined even in samples high in phosphate without a gathering step.
K -
i \ I P E R E R and hIartin (?) have recently described a procedure for the determination of trace quantities of beryllium in biological materials. The bulk of the calcium is removed hy precipitation of the sulfate, after which the beryllium is gathered by coprecipitation with ferric phosphate. The iron is removed by electrolysis with a mercury cathode, and the beryllium is coprecipitated with aluminum phosphate. The precipitate is dissolved in an alkaline stannite solution, morin is added, and a reading of the fluorescence is made. The present work was undertaken in an effort to simplify the procedure, which involves two quantitative coprecipitation steps requiring centrifugation of the phosphate precipitates. I n view of the uncertain state of purity of commercially available morin, a study of the variables affecting the fluorescence readings of beryllium with purified morin was also deemed desirable. Inasmuch as bismuth phosphate is the only phosphate of the rommon elements which is only slightly soluble in 0.5 11’ nitric : + c i c l , itnd bcruuse it S h m s WIT- litflr coprccipitation of iron,
aluminum, nickel, or zinc, the removal of phoRphate by precipitation with bismuth has proved useful in qualitative analysis I n the present investigation, it \\a found that phosphate could be removed by precipitation with bismuth in 0.5 N nitric acid without appreciable coprecipitation of tracae quantities of beryllium. Hydrous ferric oxide formed a t a final p H of 6 to 6.8 proved to be effective as a collecting agent for beryllium. The precipitate could be readily handled by filtration from hot solution rather than by centrifugation, and after washing it could be dissolved directly from the filter. Iron was removed electrolytically on a mercury cathode. The interference of calcium which is coprecipitated with the hydrous ferric oxide is prevented by the addition of Versene (tetrasodium salt of ethylenediaminetetraacetic acid). During the course of this work, it was learned that Toribara and Chen (15)had worked out a new procedure for the separation of beryllium from biological material, using an extraction with acetylacetone. By introducing this extraction method as an alternative to the hydrous ferric oxide gathering step, it is possible to determine beryllium even in samples containing large quantities of phosphate TI ithout any gathering steps, and without centrifugation. PURIFICATION OF MORIN
The isolation and purification of morin have recently been studied by various investigators ( 2 , 6, 10). I n this work the Perkin and Pate (11)method waa chosen because of its simplicity: Twenty grams of Eastman Kodak Co. technical grade niorin was extracted for 5 hours with absolute ethyl alcohol in a Soxhlet apparatus. The residue weighed 10 grams. T o the alcohol fraction was added an equal volume of water, and the precipitated morin was filtered off. The product was dissolved in ethyl alcohol and again precipitated by the addition of water. The morin was dissolved in 30 ml. of 90% acetic acid and heated to boiling. Twenty milliliters of concentrated hydrobromic acid wm added, and the morin hydrobromide was filtered off, washed with a small amount of 90% acetic acid, transferred to a beaker, and boiled wit11 water to decompose the hydrobromide. The product was
ANALYTICAL CHEMISTRY
1468
filtered, washed with water, and dried a t 120' C. The yield was on$ 0.5 gram of a yellow powder, melting point 290", with decomposition. Literature values of the melting point are 285' (6) and-290' (-9). A working solution was made by dissolving 20.0 mg. of t'he purified morin in 100 ml. of 95% ethyl alcohol. RE4GEhTS
IO0
I, 2
v)
cl
f n 6
Redistilled water was used for all solutions, because traces of copper which may be present in ordinary distilled water catalyze the fading of the fluorescence. Mercury was purified by aeration under 10% nitric acid, washing by aeration with distilled water, drying, and distillation under vacuum. Bersworth Chemical Co. commercial Versene, containing 34% of the tetrasodium salt of ethylenediaminetetraacetic acid, was used as such. Eastman Kodak Co. acetylacetone was distilled before use. -411 other solutions were prepared using C.P. or reagent grade chemicals. The standard beryllium solution was made by dissolving 69.0 mg. of beryllium oxide in 5 ml. of concentrated hydrochloric acid and diluting to 100 ml. A working solution containing 0.1 microgram of beryllium per ml. was prepared by dilution.
w
LI [L
W
t-
w
5 50
a:
0 3 -I
LL
0
z 6 a
a
6 LL
APPARATUS
A Coleman electronic photofluorometer, Model 12A, and a Farrand photoelectric fluorometer have been used. In the Coleman instrument, the ultraviolet light was filtered with a B-1-S filter (Mercury line, 365 mp) and the fluorescent light with a PC-2 filter (which absorbs below 525 mp). The highest possible sensitivity setting was used. The ultraviolet light intensity was diminished with a diaphragm with a center hole of such size as to yield proper readings with standard solutions. Using an aperture of 8-mm. diameter, a full-wale reading was obtained with a standard containing 0.01 microgram of beryllium per ml. For the Farrand fluorometer, no filter with peak transmittance in the near ultraviolet was available. However, when interference filters with peak wave lengths of 436 and 564 mp for the incident and fluorescent light were used, with an aperture setting of 6, a sensitivity adequate for the purpose was attained. This filter combination obviously does not give the maximum possible sensitivity. Two electrolysis vessels have been used. The one designed by Klemperer and LMartin( 7 ) has proved to be very good. A simple one which gives the eame results was designed. The vessel itself was a cylindrical 30-ml. separatory funnel. A stirrer made from a straight length of soft-glass tubing had at ita lower end a short length of platinum wire making contact with the mercury pool cathode a t the bottom of the separatory funnel. Around the lower end of the stirrer, about 1 cm. above the cathode surface, a platinum sleeve about 1 cm. high was fastened t o serve as the anode. A platinum wire, wound around the stirrer, made connection to another platinum sleeve around the top end of the stirrer. -4sliding contact a t the top sleeve served to make contact with the anode, while the cathode contact a a s made through the motor chuck to the frame of the motor. When the cell was being emptied, the solution was in contact with the mercury pool without the passage of current for a few seconds, but no detectable amount of iron was redissolved. Borosilicate glassware was found satisfactory. Polyethylene bottles were also used, with no observable difference. ~
Table I. Salt KC1 NaCl LiCl
-
~~
-
___
Effect of 2 iV Alkali Metal Chlorides Blank 31 22 27
Fluorometer Readings 0 01 Be/ml. 111 110 31
Corrected 80 79 4
EFFECT O F SALT CONCENTRATION
In Figure 1 are shown some of the effects of salt on fluorescence as determined with the Farrand fluorometer. Sodium chloride, sulfate, perchlorate, and pyrophosphate each caused a decrease in the blank readings obtained without beryllium in 0.05 AT sodium hydroxide solutions containing 5 X l O - 4 % morin. The corrected readings with 0.01 microgram of beryllium per ml., however, increased up to about 1.5 N salt concentration, with the exception of the pyrophosphate which caused a rapid decrease of fluorescence xith increasing concentration.
2
3 4 5 THE SALTS Figure 1. Effect of Salt Concentration on Fluorescence I
NORMALITY OF
Corrected readings for 0.017 Be/ml.: 1, NaCI; 2, NaCIOi; 3, NaiSO,. 4, Na4P201; 5, Versene. Curves la, 2a, 30, 40, and 5a blanks withou; beryllium
Table I shows a comparison of the effects of 2 S potassium, sodium, and lithium chlorides on the fluorescence. From the analytical point of view it is of interest to obtain the maximum fluorescence, and hence a sodium chloride or sulfate content of 1.5 to 2 N is desirable. At very low concentrations of morin, it was found that chloride ions have a distinct quenching effect, while sulfates, nitrates, and perchlorates do not ( 1 ) . At theusual concentration (5 X lO-4%) this quenching effect is lacking, and on the contrary sodium chloride gives a higher fluorescence at concentrations above 1.5 AM. Sandell (1b) has suggested the use of pyrophosphate to destroy the fluorescencecaused by ralcium. In the present investigation, it was found that calcium in all concentrations used (2 to 200 micrograms of calcium per ml.) decreased the fluorescence. Higher concentrations of calcium gave a precipitate. When a few drops of Versene solution &-ereadded to complex the calcium, the fluorometer reading was the same as without calcium. While pyrophosphate forms a complex with calcium, the concentration of pyrophosphate that must be used is high enough to cause an appreciable decrease in the fluorescence. Versene also caused a decrease in fluorescence, but with the small concentrations necessary to prevent the interference of calcium the effect is practically negligible, in contrast to the behavior of pyrophosphate. EFFECT OF hlORIN CONCENTRATION
In Figure 2, the Coleman fluorometer readings obtained with 0.05 and 0.1 microgram of beryllium in 20 ml. of solution mhich was 0.05 X with respect to sodium hydroxide, corrected for blank readings with no beryllium, are plotted against the concentration of morin. In these experiments, a water solution of morin waa used in order to avoid the influence of ethyl alcohol on the fluorescence. A curve of similar shape is obtained even when the solution is 2 M with respect to sodium chloride. For analytical purposes a final concentration of 5 X 10-4 to 1 X l O - S % morin appears to be best. Reaching a maximum of intensity a t this concentration, the fluorescence gradually decreases with a further increase of morin concentration. Blank readings of the fluorescence of morin alone likewise do not increase linearly with concentration.
V O L U M E 24, N O . 9, S E P T E M B E R 1 9 5 2
1469
EFFECT O F SODIUM HYDROXIDE CONCENTRATION
Sandell ( I d ) has recommended a sodium hydroxide concentration of about 0.1 N . In Figure 3, the fluorescence readings for a solution containing 0.005 microgram of beryllium per ml. and 5 X morin with and without sodium chloride addition are given for various concentrations of sodium hydroxide, together with blank readings with no beryllium. The solution contained also 2.5 volume yo of ethyl alcohol. The fluorescence of the blank increases veryrapidlywithincreasing concentration of sodium hydroxide and then decreases slowly. The mevimum intensity is a t around 0.015 N without salt and 0.005 N with 2 N sodium chloride. When beryllium is present, the maximum of the readings corrected for the blank is somewhat shifted, being about 0.05 ,V without salt and 0.015 W with 2 12' sodium chloride. Kocsis and Zador (8) have observed that morin gives two color changes in its fluorescence in ultraviolet light, one a t pH 8 to 9.8 and t h e other a t pH 3.1 t o 4.4 in 50% ethyl alcohol solution. In the present work, i t was observed t h a t t h e fluorescent color was yellowish in 0.005 N sodium hydroxide, yellowish green in 0.05 N , and bluish green in 0.5 N sodium hydroxide. Using a concentration of 2 X 10-4y0 morin the Coleman fluorometer readings were 30,45, and 20, respectively. In 1 N sodium hydroxide, using 5 X 10-4yomorin, no additional fluorescence due to 0.1 microgram of beryllium was obtained. The fluorescent light was bluish green in color. From the analytical viewpoint, the optimum concentration of sodium hydroxide is 0.05 N , a t least when the final solution contains 2.5y0 ethyl alcohol by volume and has a small salt concentration. When a sodium chloride concentration of about 2 N is used, it is advisable to use the same concentration of sodium hydroxide in order to get better reproducibility. Judging by the lower p H range reported by Kocsis and Zador for the color change in .!joy0ethyl alcohol, the optimum pH range varies somewhat with solvent.
To determine the reversibility of the "alkali quenching," a highly alkaline solution was acidified to determine whether the fluorescence increases to its expected value. This was found t o be true for the morin alone and for its beryllium compound. EFFECT OF TEMPERATURE
JVhen low concentrations of morin were used, the intensity of fluorescence increased rapidly with decreasing temperaturea. In Figure 4 are shown a family of curves obtained using 1.2 X lO-5% for final concentration of morin with various concentrations of beryllium, in 0.1 N sodium hydroxide in the presence of 6% alcohol by volume. In all cases the phenomenon was reversible-Le., the same fluorescence vias obtained after heating and cooling back to the same temperature. On the other hand, when the morin concentration was increased approximately 100-fold, the temperature sensitivity was only 0.1 to 0.2 a8 great as was obtained with the very low morin concentrations.
" w
I-
g201/ J LL
L
0.0 5
0.I
OF NaOH Effect of Sodium Hydroxide Concentration NORMALITY
Figure 3.
lo. Blank without salt 20. Blank with 2 M NaCl 1. 0.0057 Be/mi. without salt 2. 0 . 0 0 5 ~Be/ml. with 2 M NaCl 1 and 2 corrected for blank
The fluorescence of morin alone was found to be practically temperature-independent in both aqueous and alcoholic solution. The temperature sensitivity of the morin-beryllium compound was decreased by the addition of alcohol. NATURE O F BERYLLIUM-MORIN COMPOUND
~~
~
0.5
Figure 2.
I
1.5
2
P E R C E N T M O R I N .IO-' Effect of Morin Concentration on Fluorescence 1. 2.
0 . 0 0 2 5 ~Be/ml. 0 . 0 0 5 ~Be/ml.
The decreasing intensity of fluorescence a t higher alkali concentration appears to be due to an ionization of the morin molecule as an acid, giving thereby a negative ion which does not form a complex with beryllium.
Schantl (13) has shown that aluminum in acid solution forms with morin a compound, AI(C,sHgO~),,which fluoresces in the form of a colloidal suspension. In alkaline solution, where aluminum is present as the aluminate ion, no fluorescent compound is formed. White and LoRe ( 1 7 ) observed that the fluorescence is temperature-dependent (an increase of 5.5% per degree with decreasing temperature between 26" and 30" (3.). T'enturello (16) claimed that beryllium is in the form of BeOs-when it fluoresces a i t h morin. On the other hand, Britton (3) has shown that beryllate is not formed at pH values below 13, although precipitated beryllium hydroxide is partly redissolved in the p H range between 9 and 13. Fricke and Humme (4) explain this phenomenon on the basis that there are two different forms of beryllium hydroxide; the unstable and soluble form upon standing changes to the more stable and insoluble
ANALYTICAL CHEMISTRY
1470 a- form which precipitates. The a- form by aging changes to a still more insoluble 8- form. Beryllates (NaHBeOz and NazBe02) are formed only in very concentrated (10 N ) eolutions of sodium hydroxide. It seems, therefore, that the beryllium is present not as a beryllate but as a soluble, highly hydrated hydroxide as the particular range of alkalinity where the fluorescenceis obtained. As pointed out above, the fluorescence depends also upon the ionic state of morin. The reversibility of the temperature effect obtained with low concentrations of morin is evidence against a colloidal compound. A plausible assumption which appears to satisfy the experimental observations is that a beryllium ion reacts with two morin molecules, each of which has lost two hydrogen ions, t o form a fluorescent beryllium morinate anion. Further investigation is necessary, however, to establish definitely the nature of the fluorescent species. SENSITIPITY OF MORIN METHOD
In the Coleman fluorometer, the blank could not lie compensated when the full incident light intensity xas used. By adjusting the intensity of the incidrnt light, the full scale reading was made to correspond to a concentration of 0.0032 micniogiain of beryllium per ml. In the Farrand fluorometer no compensation for blank is possible. Using the light intensity given by aperture 6, the reading for a concentration of 0.005 microgram of beryllium per ml. could be set a t 100, the corresponding blank reading being 55. Taking as a sensitivity limit a deflection of 10 scale divisions, the sensitivity using pure solutions was 0.006 microgram of beryllium with the Coleman fluorometer (20-ml. final volume) and 0.01 microgram of beryllium with the Farrand (IO-ml. final volume). In the actual samples, a sensitivity limit of the order of 0.01 to 0.02 microgram of beryllium in the total sample appears to be a reasonable estimate. If an iris diaphragm could be used t o obtain continuous adjustment of the ultraviolet light intensity, one could omit taking an aliquot part of a sample solution of high beryllium content, and instead adjust the reading to full scale, and then using the same setting measure the fluorescenee of a standard and a blank. The linearity of the fluorescence with beryllium concentration was found to hold, as stated by several investigators, from 0 to at least 0.015 microgram of beryllium per ml SEPARATION METHOD
Preliminary experiments showed that phosphate could be precipitated as bismuth phosphate in 0.5 N nitric acid, and the excess bismuth could be precipitated with hydrogen sulfide without coprecipitation of beryllium in amounts detectable by spectrographic analysis. Hydrous ferric oxide carried down all the beryllium a t a pH of 6 or above, while a t pH 5 the recovery was 50%. This observation is in agreement with Britton (3), who found that beryllium hydroxide begins to precipitate a t a p H of 5.69. Removal of the iron by 8-quinolino1, extracting the iron and excess reagent with chloroform, proved unsatisfactory because of the interference of traces of the reagent with the fluorescence readings. Another modification was tried, in which the excess bismuth ion was precipitated together with the iron as the hydrous oxide. Because of the insolubility of the bismuthyl salts formed this method mas inconvenient, although good results were obtained. During the precipitation of bismuth phosphate, chloride must be absent because of the formation of soluble chlorobismuthate complex ions. Chloride is readily removed by evaporation almost to dryness with nitric acid. Samples of 0.1 to 1 gram of ash are convenient t o handle, but if larger samples of high calcium content, such as bone ash, are
to be analyzed it is advisable to remove the bulk of the calcium by the procedure of Klemperer and Martin ( 7 )so that the volume of the solution will not be too large a t the point where beryllium is precipitated. During the electrolysis, the iron is completely removed after 1 hour, using a current of 0.3 ampere. This was checked with o-phenanthroline and thiocyanate. Typical results are given in Table 11. Combining the bismuth method for phosphate removal with the extraction method of Toribara and Chen (15), it is possible to determine beryllium without any gathering step. Following the removal of phosphates and the excess bismuth, the nitric acid is removed by adding sulfuric acid and evaporating to fumes. The solution is then electrolyzed and beryllium acetylacetonate is extracted into benzene and back into hydrochloric acid. The small amounts of organic matter soluble in the acid are destroyed by gentle ignition in a platinum disk. The beryllium is dissolved in concentrated hydrochloric acid and after most of it has been boiled off, the solution is neutralized and the procedure is completed with the morin method.
A few results of the combined procedure are shown in Table 111. Klemperer and Martin (7) have suggested the use of stannous chloride to prevent the fading of the fluorescence. It was found that the fading is more pronounced in solutions of high salt concentration than in solutions having no added salt. When stannous tin was added (either as stannous chloride to the acid solution or stannite to the alkaline solution), both the blank and sample readings increased slightly. h Concentration of 0.05% tin(I1) changes the readings only a few per cent and is sufficient to prevent fading during 1 hour. PROCEDURE
Dissolve a 0.1- to 1-gram sample of ash in 10 ml. of concentrated nitric acid, and evaporate almost to dryness. Add another portion of acid and repeat the evaporation. Neutralize the excess nitric acid with 1.5 M sodium carbonate solution. Make the solution 0.5 A' with respect to nitric acid by adding 1.6 ml. of concentrated nitric acid to a final volume of 50 ml. Heat the solution nearly to boiling, and add to the hot solution bismuth nitrate solution (0.1 Jf bismuth nitrate, 0.5 N nitric acid) dropwise in 0.5-mI. portions as long as any precipitate is formed. h excess of 1 to 2 ml. of bismuth solution ifi recommended. A simple spot test, carried out by placing a drop of sample solution on a filter paper and holding the spot in a stream of hydrogen sulfide for a few seconds, shows that the precipitation is complete if a distinct brown spot is formed. To remove quantitatively 50 mg. of hosphate, 6.5 ml. of 0.1 M bismuth solution is required. Filter t i e bismuth phosphate precipitate using a medium-porosity fritted-glass funnel, and wash it twice with hot 5-ml. portions of 0.3 iL' nitric acid. Transfer the fiolution to a 250-ml. Erlenmeyer flask and saturate it with hydrogen sulfide. Filter off the bismuth sulfide, using a fritted-glass funnel. Boil the solution for 10 to 20 minutes in order to remove the excess hydrogen sulfide. Add to the solution 5 ml. of ferric chloride solution (containing 2 mg. of iron er ml., 0 1 N with respect to hydrochloric acid). A4djustthe p g t o 6 t o
Table 11.
Recovery of Beryllium by Iron Precipitation iMethod Be .4dded,
r
Pure 125
0.1
b01
rile.
0.1 0.1 0 0.5
Crt
0 5
PO,
0 5 0.5
n i
0.1 0.2 0.1 0.05 a b c
S o Versene used. Bismuth removed with iron. Berylliuni added before rtshing.
Be Recovered, Y
%
Recovery
0.1 0.075 0.080 0 0.48 0.40 0.45 0.5 0.091
0.1 0.18 0.1 0.05
91 100 ..
90 100: 100
V O L U M E 2 4 , NO. 9, S E P T E M B E R 1 9 5 2
1471
and add a few drops of glacial acetic acid, followed by concentrated ammonium hydroxide until the p H is between 4 and 5. Place the solution in a 125-ml. separatory funnel, add 4 ml. of acetylacetone, and stir the mixture mechanically vitk a motor stirrer for 5 minutes.
Table 111. Recovery of Beryllium by Extraction hZethod Saml)le Pure sol. 200 n i ~b. j n e ash
20
40
oc
GC
Figure 4. Effect of Temperature 1. 2. 3. 4. 5.
No beryllium 0.0047 Be,’ml. 0 . 0 0 8 ~Be/ml.
0.012~Be/ml. 0 . 0 2 0 ~Be/ml.
Bc Added, 0.10 n.in 0.03
-,
Be Found. y 0.in 0.10 0.046
c,
,C
Recowr~ I00 1 00 02
Add 20 nil. of benzene and stir for 15 minutes. Check the pH of the aqueous layer before discarding (if below 4, add ammonia to raise the pH t o between 4 and 5 and repeat the acetylacetone step). ’\\-ash down the separatory funnel with about 20 ml. of water (do not stir or emulsions result.) and discard the water. Add 15 nil. of 5 N hydrochloric acid and stir for I5 minutes. Transfer the acid layer into a platinum disk, evaporate to dryness, and ignite gently over a gas flame until the organic residue has disappeared. Add 5 ml. of concentrated hydrochloric acid, evaporate most of the ac,id, and neutralize it using p H paper and 1 A‘ sodium hydroxide. Transfer t o a 10- or 20-ml. volumetric flask. Add sufficient sodium chloride (calculated from the consuniption of sodium hydroxide) t o bring the final concentration to above 1.5 111. .idd morin and stannite solution as described aborc. LITERATURE CITED
t i 3 using 4 A ammonia, arid testing with pH papel’. 130il the dolution for a minute, filter the precipitate, using a fritted-glass funnel, and wash twice wit,h hot n-ater. To dissolve the precipitate, add 1 ml. of hot 4 -V sulfuric acid to the funnel. Collect the solution in a large test tube, and evaporate over a gas flame to fumes in order to remove coprecipitated nitric acid. .lfter cooling add 5 to 8 ml. of water, dissolve the residue by boiling, and transfer the solution to the electrolysis vessel. Carry out electrolysis with 0.3 ampere of current (6 to 8 volt~s)and after 10 to 15 minutes add 2 ml. of 1 A- sodium hydroxide. Continue electrolysis for an additional 40 minutes, and while the current is on, drain off the mercury cathode. Transfer the solution into a 20ml. volumetric flask, and neutralize using 1 N sodium hydroxide and p H paper. Add sufficient 3 M sodium sulfate (calculated from the sodium hydroxide consumption) to bring the final concentration to about 0.75 31. Then add 2 ml. of freshly prepared stannite solution (1yo solution of stannous chloride dihydrat,e in 0.5 N sodium hydroxide), 0.1 ml. of Versene solution, and 0.5 ml. of morin solution, and fill the flask to the mark with redistilled water. Prepare a t the same t h e a blank and a standard for fluorescence measurements. i L T E R b a T I \ I.. \ l t T H O I ) (4CETYLACETORE EXTRACTION) ( 1 5 )
Follow the ahoic piocedurc thiough the ienioval of the bieniuth sulfide. Tlirn :tdd 1 1111 of roncentrated sulfuric acid to the solution and evapoiatr to fumes. (If the sample contains much calcium, the aniount oi sulfuric acid niust be greater.) Filter off any calcium sulfate using a fritted-glass funnel, and electrolyze the solution as deacribcd above -kt this point the volume of eolution is about 30 t o 35 nil Transfer it to a 100-1111 beakpr
(1) Bishop, E., Anal. chin^. Acta, 4, 6 (1950). (2) Ronner, J. F., Jr., University of Rochester Atomic Energy Project, Rochester 20. 1;.T., Rept. UR-I11 (1950). (3) Britton, H. T. S.,“Hydrogen Ions,” p. 258, Kew York, D. Van Kostrand Co., 1929. (4) Fricke, R., and Humme, H., Z . anorg. C h a . , 178, 400 (1929). (5) Haley, T, J.. and Bassin, M.,J . Am. Phann. Assoc., 40. 111 (1951). (6) Her& J.. Monatsh., 18, 700 (1897). (7) Klemperer, K . J’., and Martin. A. P., ANAL.CHEM.,22, 828 (1950). (8) Kocsis, E. A , and Zador, G., Z. ana2. C h e w , 124, 42 (1942). (9) Kostanecki. St. v., Lampe, V., and Tambor, J.. Em., 39, 625 (1906). (10) XIorris, Q. L., Gage, T. B., and Wender, S. H., J. Am. Chew. Soc., 73, 3340 (1951). (11) Perkin, A. G., and Pate, L., J. Chen~.Soc., 67, 649 (1895). (12) Sandell. E. B., “Colorimetrir Determination of Traces of Metals,” p. 196, New York, Interscience Publishers, 1950. (13) Schantl, E., Mikrochemie, 2, 174 (1924). (14) Swift, E. H., “System of Chemical Analysis for the Common Elements,” p. 305, Yew York, Prentice Hall, Inc., 1939. (15) Toribara, T. Y., and Chen. P. S., J r . , AN.41.. CHEM.,24, 539 (1952). (16) Venturello, G . , Ricerca sci., 13, 7 2 6 (1942). (17) White, C . E., and Lowe, C. S., IND.EKG.CHEM.,ANAL.ED.,12, 229 (1940). RECEIVED f o r review Soveniber 15, 1951. hccepted June 6, 1952. Investigation conducted under the sponsorship of .4tomic Energy Commission, Contract hT (11-1) 6 7 , project i .
