polyethylene containers, in an attempt t o recover adhered Ag+, caused some losses of -4g+ from the resin. The use of such solutions for recovery may be facilitated by using more than 1 gram of Illco - 211W resin for the column. The obvious necessity for use of polyethylene in all places of contact of a Ag+ solution with a solid medium should emphasize the meticulous care required in sample collection. It certainly is not possible to allow rain water samples for Ag+ analysis to stand in metal containers for days before removal for analysis. The use of glass is highly unadvisable since AgT is tightly adsorbed on the surface (IS).
LITERATURE CITED
Blaedel, W. J., Meloche, V. y,, “Elementary Quantitative Analysis,” pp. 271-308, Row, Peterson and Co., Evanston, Ill., 1957. ( 2 ) Bode, H., 2. anal. Chern. 144, 165 (1)
(1955). (3) Cave, G. C. B., Hume, D. S . , ANAL. CHEM.24,588 (1952).
(4) Diehl, Harvey, Butler, J. P., Analyst
77, 268-72 (1952). (5) Firsching, F. H., ANAL.CHEM. 32, 1876 (1960). (6) Friedeberg, H., Zbid., 27,305 (1955). (7) Griess, J. C., Lockhart, B. R. (to
U. S. Atomic Energy Comm.) U. S. Patent 2.612.470 (Seot. 30. 1952). (8) Handliy, T. H.; Dean, J. A.,‘ANAL. CHEW32, 1878 (1960). (9) Koenig, L. R., Zbid., 31, 1732 (1959).
(10) Lord, S. R., Jr., O’Seill, R. C., Rogers, L. B., Zbid., 24, 209-13 (1952). (11) Xorwitz, George, Anal. Chim. Acta 5, 106-8 (1951). (12) Schwenck, J. R., personal com-
munication, Department of Chemistry, Sarramento Junior College, Sacramento,
Cnlif (13) Underwood, A. L.,
Burrill, A. M., Rogers, L. B., ANAL. &EM. 24, 1597
(1952).
RECEIVEDfor review July 13, 1961. Accepted Kovember 20, 1961. Work partially supported through Grant No. G 8216 from the National Science Foundation to the Institute of iltmospheric Physics of the University of Arizona. Contribution from the Brizona Agricultural Experiment Station, Technical Paper KO.672.
Gas Chromatographic Identification of Major Constituents of Bubbles in Glass F. R. BRYAN and J. C. NEERMAN Scientific laboratory, Ford Motor Company, Dearborn, Mich. Experiments with a standard chromatographic system and column material indicate that gas chromatography offers a feasible procedure for identification of major constituents of bubbles in glass. Detectability approaches 0.01 PI. for either nitrogen or carbon dioxide. Sulfur dioxide i s detectable to 0.1 PI, The method described has quantitative usefulness for nitrogen and carbon dioxide determinations, but requires an order of magnitude improvement in sulfur dioxide sensitivity to compete favorably with mass spectrometry.
C
has recently been devoted to the sampling and analysis of bubbles in glass by mass spectrometry (2, 3). Mass spectrometric techniques are reported to provide quantitative accuracies for major constituents to within =t2% when bubbles of approximately 1 pl. are involved, and within = t l O % when dealing with 0.05-p1. bubbles. Detectability limits for various gaseous constituents by mass spectrometry are reported to range from 0.001 t o 0.01 pl. Although mass spectrometry is adequate in respect to detectability and accuracy for the analysis of micro-sized bubbles, there is concurrently a need for a simple and inexpensive means of identifying the major constituent of typical bubbles of about 0.5-p1. size. This requires an analytical system with detectabilities of the order of 0.1 pl. or better, since most bubbles in glass
278
ONSIDERABLE EFFORT
0
ANALYTICAL CHEMISTRY
exhibit a gas pressure of about atmosphere (2). Because gas chromatography often provides advantages of simplicity and economy over mass spectrometry, the detectability capabilities of a standard chromatographic system was investigated in respect to gases frequently encountered in commercially produced plate glass. According to previous analyses of bubbles occurring in this same type of glass, the major constituents are most likely to be nitrogen, carbon dioxide, and sulfur dioxide (8). The literature indicates that both nitrogen and carbon dioxide are detectable chromatographically in volumes as small as 0.01 pl. (1). Corresponding detectability data for sulfur dioxide were not readily found. It seemed reasonable to expect, however, that all three gases might be resolved by one column material, and that any one of the three gases might be detected if it were the major constituent of a normal sized bubble. EXPERIMENTAL
Instrument Assembly. The chromatographic system is assembled principally from individual commercial components. Helium carrier gas flows through t h e system at a rate of 30 cc. per minute. A 6-foot column of tritolyl phosphate in a 1/4-inch diam. copper coil is submerged in a constant temperature oil bath held t o 26 i 0.5” C. A Gow-Mac thermal conductivity cell, operating at 330 ma.,
is used as detector. Signal is fed to a multirange recorder with maximum sensitivity of 1 mv. full scale. Recorder chart speed is 0.3 inch per minute. Immediately ahead of the column, a bubble-breaker sample introduction assembly is installed in the helium line. This assembly consists of a modified bellows valve described previously (2)’ Sampling Procedure. Glass samples containing bubbles are c u t t o a size slightly less than ‘/*-inch square, a n d scribed over the center of t h e bubble. T h e sample is placed in t h e bubblebreaker, and helium flow is established to purge t h e sample chamber of air. During this period, helium should be vented from t h e system prior t o reaching the column, since moisture from the air will otherwise be retained by the column and slowly eluted t o interfere with the subsequent sample analysis. After purging the sample chamber, the helium flow is directed through the column, and the signal base line is established on the recorder. At this stage, any residual air which may be issuing from the sample chamber will be evident within a 2-minute period as a nitrogen peak. With the base line established and the recorder on maximum sensitivity, the bubble is broken allowing the contents to be released into the helium stream. Column Resolution. T h e 6-foot tritolyl phosphate column was selected from those available a n d probably does not represent t h e best possible
v)
z
- 40
0 E
- 30 L n a
W
n
m
z 0 ?2
a
- 20
0 0 W
a
2 n
- 10
a: W
!
n 0 0 W
ul 4
+
'p O
a
I5
IO
5
start
-MINUTES-
a:
Figure 2. Chromatogram of bubble which apparently contained both Nz and COz. Estimated bubble volume 3.6 PI., gas volume (STP) 0.9 pl. Recorder sensitivity 1 mv. full scale.
-
MINUTES
Figure 1 . Chromatogram of a 2-ml. blend of Nzr COz, and SO2 containing 6 PI. of each gas. Recorder sensitivity 10 mv. full scale for Nz and CO2; 1 mv. full scale for SOz.
column from the standpoint of optimum resolution of these particular gases. Introduction of a mixture of the three gases reveals t h a t N2 is first to elute after only 1.5 minutes. COz quickly follows at 1.7 minutes. The heavier SOz elutes a t approximately 1T minutes to form a relatirely broad peak. Although COz and S2 peaks are barely resolved, the separation is sufficient for identification. Substitution of a short silica gel column will provide more than adequate separation for these two gases. The SO2 elutes relatively late, and with considerable tailing. Again, if elution times are important, a short silica gel column, after eluting 3 ' 2 and CO2, can be heated to elute SO2 within 4 minutes. System Sensitivity. T o estimate the detectabilities for the gases involved in bubbles, a blend was prepared consisting of known quantities of Nz, COP, and SOz in helium. Each milliliter of blend contained approximately 3 pl. of each of the three gases. A hypodermic syringe was used to inject milliliter quantities of the blend into the chromatographic system. The chromatogram shown in Figure 1 was obtained from 2 nil. of the described blend. Therefore, the peak heights are attributable to quantities of about 6 p l . of each gas. The first two peaks, NZand Con, were recorded a t a 10-mv. full scale recorder sensitivity, and the SO2 peak recorded at 1 mv. full scale. Sensitivities to Nz and COZ are similar, each providing
about 10 divisions deflection per pl. on the 10-mv. full scale recording. On a 1-mv. full scale record, therefore, 1 division deflection should be detected from 0.01 pl, of either N2or COZ. The sensitivity to SOz is about an order of magnitude less. The peak shown in Figure 1 was recorded from the 6 pl, quantity of SO2 a t 1-mv. full scale recorder sensitivity. This would indicate that quantities of the order of magnitude of 0.1 pl. of SO2 m-ould be required to provide one full division deflection. Bubble Identification. K i t h the instrument assembly and procedure described above, chromatograms were made of a number of bubble samples. A few samples did not break properly, and blank runs were made shon ing no peaks. Several bubbles contained
principally one gas, most frequently nitrogen. Sulfur dioxide, R hen found, is usually present as the major constituent, while carbon dioside is usually found in combination with significant quantities of either nitrogen or sulfur dioside. I n all cases where a chromatogram was obtained from the bubble, the peak heights accounted for the major portion of the estimated gas content of the bubble. Volumes of the bubbles were calculated from physical dimensions, and this estimated volume was corrected to standard temperature and pressure to provide the estimated gas content. Two bubble chromatograms are shon n to illustrate eltremes of resolution and sensitivity encountered. Figure 2 is the recording of a bubble containing a combination of Sz and Con. Bubble volume mas estimated to be 3.6 pl. Gas content (STP) is therefore approsimately 0.9 pl. The 40division KZpeak together with the 46division COZ peak accounts for practically all of the expected gas content. The chromatogram in Figure 3 is obtained from a bubble of only 0.1-p1.
- 30 - 20
-MINUTES
Figure 3. Chromatogram of bubble estimated from dimensions to contain 0.1 pl. of gas. Small deflection at approximately 17 minutes indicates the presence of sulfur dioxide. VOL. 34, NO. 2, FEBRUARY 1962
279
estimated gas content. Xeither S2 nor CO2 is observable. ilt 17 minutes, however, a 1-division deflection indicates the Presence of Son. This one division, considering the system’s sensitivity to SOz, accounts for the entire sample volume. CONCLUSIONS
There are various means by which a gas chromatographic system can be
improved for enhanced sensitivity to specific gases. An investigation of detectors, columns, and operating ternperatures could perhaps bring the gas chromatograph into complete quantitative lvith the spectrometer for the analysis of bubbles in glass. I n the meantime, standard chromatographic systems can serve the useful purpose of qualitative and semiquantitative identification of major
constituents of medium and large size bubbles commonly found in glass. LITERATURE CITED
(1)TKlaasse, J. hf., HamPton, \v., Paper Lo. 6-H60, Winter Conference, Inst. Soc. Am., Houston, Feb. 1960. ( 2 ) Seerman, J. C., Bryan, F. R.,ANAL. ( 3 ) Todd,3 1 9B.532-5(1959). J., J . Soc. Glass Technol. 40, 32-ST (1966). R~~~~~~~~ for revielr- september 5, 1961. Accepted November 27, 1961.
Radiochemical Analysis of Irradiated Polyphenyls F. F. FELBER, Jr.,’ and R.
C. KOCH
Physical Sciences Department, Nuclear Science and Engineering Corp., Pittsburgh, Pa.
b
Analytical procedures have been developed for radiochemical determination of 15 radionuclides in small quantities of irradiated polyphenyls. After a carefully controlled treatment with perchloric acid, the procedures utilize sequential elemental separations to provide optimum analytical sensitivities, Nine of the fifteen nuclides have been analyzed in sufficient quantities and at net counting rates sufficiently high to permit statistical evaluation of the procedures. Average precisions, at the 9570 confidence level, achieved in a series of replicate analyses for these nine nuclides varied from 3.4 to 5.2%.
A
have been developed for radiochemical determination of 15 activation and fission products in irradiated polyphenyls and related organic materials. These procedures have been uspd routinely to determine radioactivity concentrations in the coolant of a n organic moderated reactor and to obtain data in engineering tests of systems for treatment of radioactive organic wastes. The procedures also have been used for activation analyses for trace constituents in a variety of solid and liquid organic materials. Many of the radioactive nuclides present in the irradiated polyphenyls are expected to be bound chemically in one of the several constituents of the matrix. This bonding may occur either because a bound atom is activated without a net rupture of its chemical bonds or because i t reacts, after its formation, with an irradiation-induced free radical NBLTTICAL PROCEDURES
Present address, Connecticut Aircraft Nuclear Engine Laboratory, Pratt and m’hitney Corp., Middletown, Conn. 280
ANALYTICAL CHEMISTRY
to form a stable molecule. For these reasons, i t was deemed necessary to destroy the organic matrix and produce a n aqueous solution in which the radioactive species are present as inorganic ions. Two methods of sample treatment were considered: combustion of the sample in a closed system with quantitative recovery of resultant volatile and nonvolatile combustion products, and dissolution with a strongly oxidizing solvent. The first method n a s rejected on the basis of two considerations : the difficulty of ensuring chemical exchange between tracer and carrier states of the multivalent elements, and the difficulty in quantitative recovery of the volatile carrier-free radioactivities liberated during the combustion. The diss-olution procedure selected involves sequential treatment of the polyphenyls with nitric and perchloric acids in the presence of macro quantities of carriers for the nuclides to be assayed. Due to the potential hazard associated with the vigorous exothermic reaction betreen perchloric acid and the samples, i t is necessary to control the sample size, the ratio of solvent volume to sample mass, and the rate a t which heat is applied to initiate the reaction. If attention is given to these parameters, the reaction rate of the perchloric acid with the organic material can be controlled with safety. The limitation on sample size and the desirability of minimizing the number of aliquots of sample to be dissolved dictate certain requirements for the analytical procedures. Since analyses for as many as 15 nuclides are required in one sample, serious limitations on analytical sensitivities may be introduced if separate aliquots of the sample solution are used for each nuclide. Therefore, a sequential separation pro-
cedure was devised for the required elements in a relatively large fraction of the solution. Two sample aliquots are dissolved. One solution is used for analysis of the cations, while the other is used for nuclides rt hich form anions. The individual elements are then separated, purified, and their radioactive nuclides are assayed by measurement of their respective beta or gamma radiations. ANALYTICAL PROCEDURES
Sample Dissolution. Separate, weighed aliquots of t h e polyphenyl sample, not exceeding a mass of 15 grams each, are combined in 4-liter Erlenmeyer flasks n ith known quantities of carriers for t h e desired nuclides and holdback carriers for other important nuclides. hpproximately 20 ml. of 16.Y HKOs are added per gram of sample to be dissolved. When no further reaction is observed with the boiling acid, the solution is cooled, and approximately 15 ml. of perchloric acid per gram of sample are added. The mixture is heated slowly until evolution of perchloric acid fumes. Heating is then terminated, since the reaction is sufficiently exothermic t o maintain itself nearly to completion, After the vigorous reaction has subsided, additional heating is usually required to effect dissolution of final traces of the sample. Each solution is then divided into three approximately equal portions for replicate analyses. Since the carriers are added t o the sample in knonn amounts prior to dissolution, it is not necessary to measure these aliquots quantitatively. The solutions for both the cation and anion analyses are evaporated to volumes of approximately 25 ml. Initial
Separation
Procedures. initial separation method for the three anionic nuclides, P32, 535, and Se7j, which hare been analyzed routinely
APU’IOSICELEMENTS. The
