for later portions of the elution scheme. The programming of several buffers into a gradient vessel offers a finer control of the s h m e of the gradient than the use of a single concenk&ed, remote p H inflow. The flow of gases or samples for gas chromatography could be automatically Programmed, for example, to repeatedly analyze a flowing stream by
injecting into the chromatograph the constant volume sample trapped in the cross-drilled hole in the Teflon plug of a four-arm stomock.
and T. R.Kressman~ed8.j PP. 16C-2, lg5'. R. A., ( 2 InterscienceY ) Hamilton, New P. B., Anderson,
A ~ ~cHEM. ~ , 31, , 1504 (1959). (3) Kellie. A. E.. Wade. A. P.. Biochern. J . 66, igg'(i957j. (4) Peterson, E. A., Sober, H. A., ANAL. CHEM.31, 857 (1959). (5) Smith, Ivor, "Chromatographic Techniques," pp. 252-4, Interscience, New York, 1958. ~
LITERATURE CITED
(1) Hale, D. K., "Ion Exchangers in
Organic and Biochemistry,'J C. Calmon
Multiple Hydrogenation insert R. A. Eisenhauer and R. E. Beal, Northern Regional Research Laboratory, Peoria, 111.
o
HYDROGENATE
threads, except for the bottom of the sixth section. All internal threads have a l/lsinch relief at the base of the threads. The bottom of one section forms the top of the next, except for the first and sixth sections. The first section has a 6/16-in~hthreaded cap and the sixth, a flat bottom and no threads. Teflon gaskets, cut from a lj16-inch sheet, were used between each section. The gaskets fit between faced surfaces giving an excellent seal. A '/,-inch hole was drilled in the center of each section, and a piece of l/d-inch pressure tubing, 3/4 inch long, was welded in each hole projecting into the section thus giving an opening for hydrogen. The inside diameter of the pressure tubing is a/92 inch. Without this tubing, leakage occurs and samples intermix. Procedure. Materials t o be hydrogenated are placed in each of the six sections of t h e insert and a suitable catalyst is added. T h e sections are fitted together with fingertip pressure. Knurled surfaces on each section prevent t h e fingers from slipping over t h e machined stainless steel. This pres-
samples on a semi-
T micro scale, a stainless-steel insert, which has a capacity of 10 ml., is avail-
able for use with an Aminco, 300-ml. reaction vessel. However, when many samples must be hydrogenated for analytical purposes, time becomes a n important factor because only one sample can be hydrogenated at a time with the 10-ml. insert. Methods for hydrogenating several samples simultaneously were explored, and a new insert was designed that allows the hydrogenation of six samples concurrently. EXPERIMENTAL
Fabrication. Individuai sections of this insert were c u t from solid stainless-steel rods of approximately l 6 / 8 inch diameter. The inside of each section was bored to a depth of inches, and the section was cut to approximate dimensions (Figure 1). The top of each section n-as threaded with 24 internal threads, the bottoms with 24 external
sure on t h e Teflon gaskets is sufficient to obtain an adequate seal to prevent leakage. Hydrogen inlet holes need not be aligned because the pressure tubing extends to the center of each section, and with approximately 1 to 5 grams in each section, no leakage occurs. When the insert is completely loaded and assembled, it is inserted into a n dminco 29/16-in~h0.d. micro-series reactor. This reactor is bored from a solid forging and has an over-all length of l13/a inches. The reactor containing the insert is then placed in a rocker assembly, which includes a heating jacket and means for introducing hydrogen. The pressure vessel tilts through an angle of 30' at 36 cycles per minute. This movement gives the material in each section ample agitation and catalyst contact. The Northern Laboratory is a laboratory of the Northern Utllization Research and Development Division, Agricultural Service, U. S. De artment of Agriculture. Mention of tra& names is for identification only and doea not imply endorsement by the Department.
, \I/l6''
Teflon gasket.
I
-I
I P4 Eshrnol Ihraodi.
Figure 1. Insert for hydrogenating six samples concurrently in an Aminco reaction vessel
24 Intwnal
ONE OF I TYPICAL SECTIONS
11 10
ANALYTICAL CHEMISTRY
