A N A L Y T I C A L CHEMISTRY, VOL. 50, NO. 3, MARCH 1978
Table 11. Total ?-ray Activities of Neutralized NaOH Solutions
IC
Activity, cpm
SampleQ
235 250 248 249 248 250 T 3 249 1946 1950
1
-
2 3 4 5
8
0
I 0
+ z w
i
Mean Background Ab Bb
6
33
0
: 4
2 I
4 mL 10 M NaOH. to 4 mL. 2
2 p L HCI from reservoir, diluted
plot of the reverse situation where basic solutions t KOH) were neutralized from HCl (12 M) reservoirs. The average rate of HC1 transfer was 0.4 mequivlmin. When 3&mL saniple beakers were used. the transfer rate decreased by 3 0 7 ~ .
0
'IME
Figure 5. HCI
543
I MINUTES)
transfer with reagent chamber
difference between the two methods for Cu, Ni, Co, Fe, Mn, Cr, and Zn. This information complemented t h a t from t h e radiotracer studies by indicating that the contamination introduced between the reservoir and the sample was also negligible. The contribution of this gaseous technique for p H adjustment is further enhanced by the facts that during the preparation of the XRF blanks (1) there was a negligible increase in sample solution volume, ( 2 ) precise control of the pH adjustment of small, unbuffered solutions was maintained easily to better than f 0.1 p H unit, (3) with a high degree of control the adjustments were performed more quickly than Kith aqueous reagents, and (4) reagent grade NH40H was used as the source for the high purity gas. In Figure 4 are plotted data from neutralizations of 10-mL HC1 solutions in 50-mL beakers with NH3 using the reagent chamber. On the average, the rate of NH3 uptake from the 250-mL reservoir is 0.7 mequiv/min. Figure 5 shows a similar
ACKNOWLEDGMENT The author thanks J. E. Kessler for his able assistance with the Microdot analyses and for his many helpful discussions.
LITERATURE CITED (1) E C. Kuehner, R Alverez. P.J. Paulsen. and T J. Murchv Anal. Chem.. 44, 2050 (1972) (2) R W Dabeka A Mykytiuk, S S Berman, ,and D S Russeil Anal Chem , 48 1203 -..11976) -, (3) M. Zief and J. W. Mitchell, "Contamination Control in Trace Anaiysis", John Wiley and Sons, New York, N.Y.. 1976, Chapter 6. (4) H. Irving and J J. Cox, Ana/yst(London), 83, 526 (1958). (5) J. M. Mattinson, Anal. Chern., 44, 1715 (1972). (6) K . Little and J. D. Brooks, Anal. Chem., 46, 1343 (1974). 17) 0. Wein. K. Wichterle, P. Mitschka, J. Suic. and M. Patek. Chem. Prum., 24 (12), 604 (1974). (8) Mississippi Chemicai Corp., French Patent 2187692, February 1974. (9) J. W. Mitchell and D. L. Nash, Anal. Chem., 46. 326 11974). 110) C. L. Luke. Ana/. Chim. Acta, 41. 237 (1968). (11) J E Kessler and S M Vincent, unpublished work (12) L A Currie. Anal Chem , 40, 586 (1968) \
~
RECEIVED for review October 6, 1977. Accepted November 1. 1917.
Rapid Packing of Coiled Glass Gas Chromatography Columns Geraldine Olerich Analytical Chemistry Division, Oak Ridge National laboratory, Oak Ridge, Tennessee 37830
Many methods have been tried in our laboratory to pack gas chromatographic columns of high efficiency and reproducibility. Because of the fragile nature of the majority of in. 0.d. glass, delicate handling is our columns, 20 ft X necessary. Until now, the most efficient method we have found was to place a small plug of glass wool in one end of the column and attach the column to a vacuum line. .A 3 ft x 1/4 in. 0.d. Teflon tube was filled with the packing material and, using Swagelok fittings, one end of the tube was attached to the column and the other end to a dry nitrogen source. The packing was forced into the column with a nitrogen head pressure of 50 psig and vibration. Several hours were required to pack the columns, apparently because of static electricity generated by the friction of the packing against the glass. The static charge caused the packing to coat the inside of the column and prevented it from moving freely to give a high density packed column. The problem can be alleviated somewhat by packing the column following heat treatment in the gas chromatographic oven. The front of the column 0003-2700/78/0350-0543$01 00/0
is connected to the inlet of the chromatograph and the empty column is heated to -200 "C for 5 min. After cooling, the column is removed from the oven and again attached to the vacuum and nitrogen lines. We realized then that most of our problems could be solved if the columns could be packed directly in the GC oven. The column packer described in this paper is a simple. inexpensive device which allows this to be done. This devict: (Figure 1 ) was constructed to fit a Perkin-Elmer Model 3920 but could be adapted to any gas chromatograph. A small glass wool plug is placed in the back end of the glass column. Two or three inches of packing is pulled into the column with vacuum to allow compacting of the glass wuol plug. The column is then placed in the C;C oven and the front end attached to the inlet as usual. The system retainer nut and the metal and glass liner are removed from the inlet and the 1/4-in.0.d. copper tube of the column packer is inserted as far as it will go into the inlet. The Swagelok is tightened to hold the packer in place. Using a small funnel, the reservoir 1978 American Chemical Society
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A N A L Y T I C A L CHEMISTRY, VOL. 50, NO. 3, MARCH 1978
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is filled with packing material. A 1/4-in.o.d. copper tube is attached to the top Swagelok fitting and the other end is connected to a nitrogen or helium tank. By applying a pressure of 60 psig and vibrating the copper tube just under the reservoir, the packing will flow into the column. When the column appears to be full, each coil is lightly vibrated with the vibro-tool and the copper tube is again vibrated until no more packing will flow into the column. If static electricity slows the movement of the packing, close the oven and heat to -200 "C. Immediately cool the oven and the packing will continue to flow. After gradually reducing the pressure to atmospheric, the column is removed from the oven and a glass wool plug is inserted in the front of the column. By this method, we have been able to reproducibly pack 20 ft x in. o.d. coiled glass columns of high density in 5 to 10 min.
'/4-1n SWAGELOK FITTING
COPPER DISK WITH '/4-!n HOLE DRIL-ED IN CEhTER
I-ln
jp' - i n
3;n
I
OD COPPER PIPE
I
COPPER 3 SK WITH 'i4-i" HOLE DRI--EO INCEhTER I-in
SHAGELOK NU- H l T H TEFLON FERRULE
L'ia-in
RECEIVED for review September 12,1977. Accepted October 17,1977. Research sponsored by the U.S. Energy Research
ODCOPPEP TUBING
THE COLUMN PACYES IS ASSEMBLED WITH SILVER SOLDER
and Development Administration under contract with Union Carbide Corporation.
Figure 1. Column packing reservoir
CORRECTION Precision of Flame Atomic Absorption Measurements of Copper In this article by Tu'. W. Bower and J. D. Ingle, Jr., Anal. Chem., 48, 686 (1976), Equation 15 should read:
g 3 = [ E , 2.303 A ] - ' [ U * *- ( t :
+
