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ANALYTICAL CHEMISTRY, VOL. 50, NO. 4, APRIL 1978
Table 111. Comparison of H, Actinometer and VPC Results % Reactiona VPC % H, satd (No. of samples) H,O ( + % Err)b 0
0
Calcd % H, satd H,O ( + % Err)c 0
7 (3) 14 ( 3 )
6 (8) 5 (10) 10 (10) 1 0 (4) 19 (10) 28 ( 5 ) 1 5 (6) a Calculated from the absorbance at 420 nm for [Fe"'(CN), 13-,emax =. 1.00 X l o 3 M-' cm-'. VPC % H, satd H,O = (Peak Height H, a t [)/(Peak Height H, satd H , O ) X 100, where f is the photolysis time. Calcd % H, satd H,O = (No. Moles H, at t)/(No. Moles H,in satd H , O ) x 1 0 0 = [ ( f a ) ( I o z )(@v (t)/mL]/(7.6 x 10'7/mL) x 100, where f a = 0.55, Io12 3.0 X l(r8einstein s - ' , @ H , , * = 0.43, f is the photolysis time. ,j)
1.0 X M HC104 and 0.10 M isopropanol. The solutions were analyzed for H2 assuming @ . H ~= 0.43 ( 5 ) . Peak heights were measured with a millimeter ruler.
injected. The reported procedure, while utilizing standard and readily available equipment, approaches the sensitivity for dissolved H2detection (- 1 x 10+ M) of the best published chromatography method ( 4 ) which requires specialized apparatus. T h e photolysis of acidic aqueous ferrocyanide solutions containing the hydrogen atom donor isopropanol, was found to provide a useful calibrated source of Hz in subsaturation concentrations under conditions nearly identical t o those employed for the monolayer experiments. As noted in Table 111, the results of the two methods are the same a t low conversions to ferricyanide. At conversions >15%, deviations occur and become increasingly larger a t higher conversions.
ACKNOWLEDGMENT I am indebted to P. Behnken, D. A. Bolon, G. L. Gaines, Jr., and J. E. Girard for loan of equipment and helpful discussions in the course of this work. LITERATURE CITED (1) K . R.
RESULTS AND DISCUSSION The analytical data observed for the detection of dissolved Hz and O2 are presented in Table 11. While the maximum volume that can be injected directly on column is limited, this method has proved more sensitive and reproducible than two systems tested in this laboratory based on stripping the gases from a larger volume of solution (1-3 mL) by passing a finely dispersed carrier gas stream through the liquid before the drying and analyzing columns (8). The long term, transient (5-10 min) decrease in carrier gas flow following liquid injection results in an irreproducible baseline which effectively limits the size of injection. T h e use of larger diameter precolumns resulted in peak broadening and consequent decrease in sensitivity. Currently, the "water-absorbing'' precolumn is changed after a total of ca. 1 mL liquid has been
Mann, N. S.Lewis, V. M. Miskowski, D. K. Erwin, G. S. Hammond,
and H. 6.Gray, J . Am. Chem. Soc., 99, 5525 (1977). (2) G. Sprintschnik, H. W. Sprintschnik, P. P. Kirsch, and D. G. Whitten, J . Am. Chem. Soc., 99, 4947 (1977);ibid., 98, 2337 (1976). (3) P. A. Jacobs, J. 6.Vytterhceven. and H. K. Beyer, J. Chem. Soc., Chem. Commum., 1977. 128. (4) A. Tolk. W. A. Linaerak. A. Kout. and D. Boraer. Anal. Chim. Acta. 45. 137 (1969) (5) P L Airey and F S Dainton, Proc R SOC London. Ser A , 291, 340, 478 (1966). (6) R. E. Hintze and P. C. Ford, J . A m . Chem. SOC., 97, 2664 (1975). (7) C. A. Parker, "Photoluminescenceof Solvtions", Elsevier, New York, N.Y., 1968. (8) J. W. Swinnerton, V. J. Linnenborn, and C. H . Cheek, Anal. Chern.. 34, 483 (1962).
RECEIVED for review October 21, 1977. Accepted December 7, 1977. This research was partially supported by the Division of Basic Energy Sciences, Department of Energy (EG-77C-02-4395).
Separation of Rhodium-103m from Ruthenium-103 by Solvent Extraction Jih-Hung Chiu, Robert R. Landolt," and Wayne V. Kessler Bionucleonics Department, Purdue University, West Lafayette, Indiana 47907
A previous paper (1) reported a procedure for the separation from Io3Ru. The yield of loBrnRh was 94 f 0.6 % , and of loBmRh the amount of lo3Ru contamination was 3.8 0.7%. Continued work to improve the separation procedure has resulted in one that is considerably better. T h e procedure of Meadows and Matlack ( 2 ) ,developed for the separation of radioruthenium from fission product waste, was modified and used in the initial steps. T h e yield of 10BrnRhwas quantitative and there was no measurable lo3Ru contamination.
*
EXPERIMENTAL Reagents. A ruthenium carrier solution containing 3 g of ruthenium chloride (Alpha Products) in 500 mL of distilled water was prepared. The solution was filtered through Whatman 41 paper. SpectrAR grade carbon tetrachloride (Mallinckrodt) was used without further purification. Ruthenium-103 in equilibrium with loSmRhwas obtained from Amersham/Searle as ruthenium chloride in 4 N HCl. A stock solution containing 1 gCi of lo3Ru/mL in 6 N HC1 was prepared. Separation Procedure. The procedure of Meadows and Matlack (2) was followed with modifications. A 0.5-mL aliquot
of the 103R~/103mRh stock solution was placed in a 60-mL separatory funnel containing 2 mL of concentrated HC1 and 2 mL of ruthenium carrier solution. With frequent swirling, 12 N NaOH was added dropwise until black ruthenium hydroxide precipitated. Ten more drops of NaOH was added, followed by 1 mL of 5% sodium hypochlorite with thorough mixing. The ruthenium hydroxide dissolved and the solution turned green. After 1 h, 10 mL of carbon tetrachloride was added, followed by dropwise addition of 6 N HC1, with swirling, until the color suddenly turned light yellowish green. Four more drops of HC1 was added. The contents of the funnel were mixed for 1 min, and the carbon tetrachloride layer containing ' 0 3 R ~ 0was 4 drained, leaving the 103mRhin the aqueous layer. The aqueous layer was extracted with an additional 10 mL of carbon tetrachloride and was then drained into a graduated 50-mL centrifuge tube. Purification of 103mRh. The aqueous solution in the tube was gently boiled over a flame for 3 to 5 min until the volume was reduced to less than 10 mL. Suspended carbon tetrachloride, residual Io3RuO4,and residual chlorine evaporated. The solution was cooled and diluted to 10 mL. A 5.0-mL aliquot was placed in a polypropylene counting tube. The lmmRhand lo3Ruactivities were measured immediately by y-ray spectrometry in the manner previously reported ( I ) .
0003-2700/78/0350-0670$01,00/0 1978 American Chemical Society
ANALYTICAL CHEMISTRY, VOL. 50, NO. 4, APRIL 1978
RESULTS AND DISCUSSION
671
lo3RuO4and possibly some nonextracted lo3RuO4. After boiling, the solution was clear and free of lo3Ru because of evaporation of both carbon tetrachloride (bp 76.7 "C) and the very volatile (3) lo3RuO4. The boiling procedure also eliminated any chlorine present as a result of the excess sodium hypochlorite. However, it was found, using potassium iodide and the starch test, that some hypochlorite remained in solution. The addition of 1 drop of 1 M sodium bisulfite solution after boiling resulted in a negative starch test. In conclusion, this method for separating loBmRh from lo3Ru is simple, fast, and efficient. The reagents used are common and only a small number are necessary. The time interval from the first carbon tetrachloride extraction to the counting of the 103mRhis only about 16 min, thus making possible a high concentration of the short lived loBrnRh. The loBmRh concentration can be further increased by boiling because the chloride form of loBrnRhis not volatile. The final p H is near neutral and sodium chloride is the only major contaminant.
The loBmRhyield of the extraction and the lo3Ru contamination of the loBmRhsolution were calculated ( I ) . The results for eight replications of the extraction and purification procedures were: loSmRhyield, 100.9 f 2.1% and lo3Ru contamination, 0.0%. The use of sodium hypochlorite as the oxidizing agent was an improvement over the previously reported ( I ) use of ceric sulfate. The oxidizing capacity of sodium hypochlorite was not affected by the presence of chloride ions. Consequently, in addition to giving quantitative yields of loBmRh, the use of sodium hypochlorite eliminated the need for fuming with 1:l H 2 S 0 4to eliminate chlorides as was required in the ceric sulfate method. Meadows and Matlack ( 2 ) reported that a pH of 4 in the aqueous phase was optimum for extraction of RuOl into carbon tetrachloride. In the present study, it was found that the optimum p H was in the range of 6.5 to 7.5. Preliminary studies also showed t h a t considerable contamination of the aqueous solution with lo3Ruoccurred when the pH was lower than 4. Two carbon tetrachloride extractions were sufficient to quantitatively remove lo3RuO4. The boiling procedure used to purify the extracted aqueous solution of lo3Rhwas efficient. In preliminary studies of the extraction procedure, when boiling was not used, the lo3Ru contamination in the aqueous phase was 0.9 f 0.8% for six replications. This contamination was believed to result from visible suspended droplets of carbon tetrachloride containing
LITERATURE CITED (1) C. E. Epperson, R. R. Landolt, and W. V. Kessler, Anal. Chern., 48, 979-981 (1976). (2) J. W. T. Meadows and G. M. Matlack, Anal. Chern.. 34, 89-91 (1962). (3) "The Merck Index," 9th ed., Merck & Co., Inc., Rahway, N.J., 1976, p 1075.
RECEIVED for review October 27, 1977. Accepted December 22, 1977.
Serial Dilution Pipet for Generating Instrument Calibration Standards Daniel S. Berry Searle Diagnostics, Inc., 2000 Nuclear Drive, Des Plaines, Illinois 600 18
Many analytical chemical determinations require the construction of a standard curve from a serial dilution of a concentrated standard solution. Although numerous commercial devices exist for pipetting and diluting individual samples, equipment for semiautomatic multiple dilutions of a standard is not readily available. The device described below is based on repeated addition and withdrawal of constant volumes of diluent and diluted standard from a concentrated standard solution. This simple apparatus can save considerable time in generating standard curves for calibrating instruments.
EXPERIMENTAL A 20-mL glass hypodermic syringe was fitted with an upper and lower mechanical stop. In the model shown in Figure 1,the upper stop is an adjustable screw and the lower stop is a length of metal tubing cemented onto the syringe piston. The syringe was fitted with a three-way valve (Hamilton) and reservoir of diluent solution with appropriate tubing. A small magnetic stirring bar was inserted into the active volume of the syringe, to mix the standard with diluent. This apparatus, in addition to a small magnetic stirrer, was clamped to a ring stand, as shown in Figure 1. In operation, a concentrated standard solution is drawn into the clean, dry apparatus by unclamping the syringe from the ring stand and pumping it into an inverted bottle fitted with a rubber septum cap until all air bubbles are removed and the syringe is filled to its maximum stop. It is then reclamped, needled down, and allowed to drain into an appropriate receiver to its bottom stop. The quantity of residual solution fixed by the length of the 0003-2700/78/0350-0671$01 .OO/O
Table I. Gravimetric Calibration of Serial Dilution Apparatus Ratio of Total grams ExDected successive Average of N k l diiu tion weights ratio and factor Run delivered of NaCl RSD 1
2
3
1.4123 0.7009 0.3484 0.1695 0.0839 1.4072 0.7003 0.3382 0.1697 0.0860 1.3949 0.6936 0.3410 0.1719 0.0863
0 112 114 1I8 1/16 0 112 114 118 1/16 0 112 114 118
2.015 2.012 2.056 2.02 2.004 2.071 1.993 1.97 2.011 2.034 1.984 1.99
2.03 1%
t
2.01 2%
i.
2.00 1%
*
1/16
bottom stop is now diluted by turning the three-way valve to admit diluent, and pulling the syringe piston to the upper stop. The magnetic stirrer is activated to mix the standard with diluent. The three-way valve is turned to let the syringe drain the diluted standard, plus the undiluted material in the needle, into the next receiver. The valve is then turned to admit fresh diluent to the upper stop and, following a few seconds mixing, turned again to drain into the next receiver. This process is repeated until the 0 1978 American Chemical Society
