and the platinum wire. Accordingly, this change of resistance was used as a correction factor in actual pore-spectra determinations. To compare the extended-range hydraulic porosimeter with the conventional Ritter and Drake porosimeter which had been in use in this laboratory
for some t i e , the pore spectrum of a commercial alumina (spherical form) was determined using both instruments. The results, shown in Figure 3, show remarkably close agreement for the two methods, and indicate that the new instrument gives resulte comparable to the conventional mercury porosimeter.
Since the sample was R commercial alumina on which virtually no other information was available, any deduction a.bout the meaning of the data would be potentially erroneous. Drake and Ritter and Drake discuss the interpretation of pore distribution determined by mercury penetration.
Microvalve and Connector for Automatic Column Chromatography Eric Schrarn' and Robert Lornbaert, Faculty of Medicine, University of Brussels, Brussels, Belgium et al. (4) have shown that S in the automatic chromatography of amino acids, mixing of the effluent PACKMAN
may be avoided by keeping the diameter of the liquid stream sufficiently small--e.g., approximately 0.7 mm. Therefore, all connectors and valves placed in the line should be of the same inner diameter and should remain watertight under sometimes rather high working pressures. Moore et aE. (1) have used B Teflon microvalve. The device described here is a similar valve, used in our laboratory for nearly a year.
-
1 Present address, Chercheur A r.66 de 1'Institut Interuniversitaire des ffciencea Nucl&irea, Brussels, Belgium
1cm.
Figure 1.
b
Connector for Teflon capillary tubing
C
Figure 3, valve
to analyzer
Detail of Teflon micro-
from column
u----v 2!!A
Figure 2.
Teflon rnicrovalve
For more cleorness saews have not all been represented
1134
6
ANALYTICAL CHEMISTRY
to control panel
APPARATUS
Connector. The connector shown in Figure l,a, is used with Bmalldiameter Teflon tubing (Pennsylvania Fluorocarbon Co.). Some dificulties are usunlly encountered in connecting such tubing, especially to glass, because of lack of elasticity and poor adhesive properties. I n the present case, watertightness and mechanical resistaneo are obtained by paasing the Teflon tubing through a sleeve, 1, of thick-walled, silicone rubber capillar tubing. Centering of the Teflon capil Iary, 2, is easier when it protrudes slightly from the silicone sleeve and when a small lodging, 3, is provided for it in the socket, 4, of the A perfectly tight joint connector. which will resist pressures of a t least 100 p.6.i. is obtained by tightening the cap, 5 . The connector, which may be assembled or disassembled as often as necessary, may be used to connect Teflon tubing to a chromatographic column (Figure 1,c), a microvalve (Figure 2) or any similar device, or to another piece of Teflon tubing. The socket part may be fixed to any piece of equipmmt, either by screwing (Figure 1,b) or by sealing with a synthetic resin, as in the case of chromatographic columns (Figure 1,c). The present connector has proved superior to ball or socket joints, because of watertight-
ness and higher mechanical resistance. Except for the silicone sleeves, all parts are made of Lucite or Teflon. Microvalve. The microvalve (Figures 2 and 3) was initially designed for use with a n automatic analyzer, of the type described by Spackman et al. (4, to replace the glass stopcock manifold which stuck easily. To reduce the over-all dimensions of the microvalve the several inlet slides, 1, are placed concentrically around the outlets, 2, 2'. Depending on their position the liquid will either be stopped or run through one of the outlets (Figure 3). The inlet is positioned in front of one of the outlets by pulling or pushing the slide a t full stroke. The slides are actuated by means of brass rods, 6, in which. a notch locates the median dead point position. Watertightness is ensured by neoprene O-rings, of 4-mm. i.d., for which a groove is provided around each opening facing the slides. Spring blades, 4, adjust the pressure. No lubricating agent is required for smooth operation. The microvalve is centered in the middle of a Lucite ring, 7, which is attached to the back side of the control panel by means of shafts, 6; the actuating rods, 6, emerge through it on the front side. The dotted parts in Figures 2 and 3 are made of Teflon, the hatched parts of stainless steel, and all others of Lucite. Inlet slides may ,be replaced easily if necessary.
APPLICATIONS
In addition to its use in the automatic analyzer of Spackman et i d . , Teflon capillary tubing may also prove useful whenever chromatographic effluents must be 'transferred without mixing between two distant points. For iostance, before being analyzed by chemical reagents the effluent liquid may be sent through a radioactivity (a, 3) or ultraviolet recorder. Or, when fraction collectors are used, the chromatographic columns may remain on a stand aside, so that, particularly for large columns, handling is facilitated. ACKNOWLEDGMENT
The authors express their thanks to Louis Ockum for his skillful cooperation in machining the equipment described. LITERATURE CITED
(1) Moore, S., Spackman, D. H., Stein, W. H., Fea'eratm Proc. 17,1107 (1958). (2) Schram, E., Lombaert, R., Anal. Chim. A c h 17, 417 (1957). (3). Schram, E., Lombaert, R., Arch. zntern. ahusiol. el biochim. 68, 845 (1960). (4) Spackman, D. H., Stein, W. H., Moore, S., ANAL. CHEM. 30, 1190 (1958). S
I
Modifications to an Ionization Detector Chromatograph for High Temperature Gas-liquid Chromatography Exploratory Studies B. J. Gudzinowicz and W. R. Smith, Special Projects Department, Research and Engineering Division, Monsanto Chemical Co., Everett, Mass. N INITIAL high temperature gasIliquid chromatography studies using an ionization detector chromatograph, hydrocarbons of lower molecular weight and complex aromatic mixtures, with some components having boiling points above 500" C., were resolved and determined by the authors. Preliminary quantitative investigations have been completed using microgram quantities of organics with accuracy and precision comparable to these obtained with conventional instruments [Gudzinowicz,
B. J., Smith, W. R., ANAL.CHEM.32, 1767 (1960)).
With continuous operation at or above 300" c., the silicone rubber con-
nectors (used with the Barber-Colman Model 10 argon ionization detector chromatograph) between the column and detector and the rubber septum in
0
b Figure 1. Schematic of modified introduction, column,, and detection systems
I
A. Stainless steel In/octlon block B. Detector Samplo-injection fitting 0.d. stainless steel tube) Water-coollng coil ('/&ch E. Sllicone rubber septum F. '/pinch 0.d. stolnless steel column G. Cartridge heater H. l/4-inch tube to '/&ch pipe stalnless stee' Swagelok Atting 1. Detector exlt J. Stoinless steel Swagelok fltting for l/le-lnch 0.d. caplllary K. l/l&ch 0.d. stainless steel capillary L Stainless steel ball ioint, 12/3 M. Glass elbow with ball lointi, 12/2 C.
D.
VOL. 33,
NO. 8, JULY 1961
1135
