Dialyzer separates macromolecules from small molecules in large volumes of solution. It takes advantage of the high area/volume ratio in commercially available 1/4-inch dialysis tubing and maintains a high concentration gradient at the dialyzing surface by counterflow

Mandeles, S.

Woods, E. C.

English

NASA Technical Reports Server

October 1967	 -	 Brief 67-10395 
NASA TECH BRIEF	
a 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Large Volume Continuous Counterfiow Dialyzer Has High Efficiency 
The problem: 
In biochemical research, the need often arises to 
separate by dialysis, macromolecules (proteins and 
nucleic acids) from small molecules (salts, urea, glu-
cose) in large volumes of solution (extracts of bio-
logical material, blood, serum). The conventional 
method of dialysis consists of filling a cellophane sac 
with the solution to be dialyzed and then suspending 
the sac in a bath to permit equilibration of the small
dialyzable solutes inside the sac with the solution in 
the bath; macromolecules cannot pass through the sac. 
The efficiency of this process depends mainly on the 
ratio of dialysis sac area/volume of liquid in the sac, 
and the concentration in the bath. Ordinarily dialysis 
baths are refreshed four or five times a day and the 
dialysis sacs are agitated by some mechanical means. 
In instances where large volumes of solution need to 
be dialyzed, the procedure is time consuming and in-
convenient. 
ANNINk	 (continued overicaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
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The solution: 
A dialyzer design that takes advantage of the high 
area/volume ratio in commercially available 1/4-inch 
dialysis tubing and maintains a high concentration 
gradient at the dialyzing surface by counterflow. 
How it's done: 
The dialyzer consists of an inner dialysis tube 
(through which the solution to be dialyzed, the re-
tentate, flows) concentric with an outer vinyl tube 
(through which the bath fluid, the diffusate, flows). 
The inner dialysis tube is held in place by plastic 
spacers at 2-foot intervals to minimize kinking and 
facilitate assembly. This dialyzer coil is extended 20 
or 30 feet, and is terminated at each end with a plastic 
connector with tubulature that permits separate inflow 
and outflow of retentate and diffusate. A dialysis coil 
constructed in this way can utilize the counterflow of 
retentate and diffusate to maintain a uniformly high 
concentration gradient. The flow of retentate and dif-
fusate is turbulent, thus aiding in maintaining a maxi-
mum concentration gradient at the membrane sur-
faces. The flow of the diffusate is continuous, elim-
inating the need to change baths, and the retentate 
can be recirculated for additional dialysis. The 
progress of dialysis can be continuously monitored by 
pH meter, UV absorption meters, or samples taken 
for, chemical analysis without interrupting the flow of 
solution. Two or more dialysis coils can be used in 
parallel to increase the dialysis capacity. 
Notes: 
1. In general, solutions can be dialyzed by this 
method in 2 or 3 hours to the same extent as that 
accomplished by conventional methods in 24 
hours.
2. This dialyzer can be used without disassembly, it 
is light and portable, and its capacity can be ex-
panded easily. 
3. Current applications of the continuous counter-
flow dialyzer are in the purification of proteins 
and nucleic acids in large scale preparations for 
research. It is also adaptable for use in pilot plant 
or full scale industrial processing of blood sera 
and other biologicals. 
4. The basic design is potentially useful in artificial 
kidney construction. 
5. Additional details describing the construction and 
use of this dialyzer are contained in Analytical 
Biochemistry, 15, 523-529 (1966). 
6. Inquiries concerning this innovation may be di-
rected to:
Technology Utilization Officer 
Headquarters 
National Aeronautics and Space 
Administration 
Washington, D.C. 20546 
Reference: B67-1095 
Patent status: 
No patent action is contemplated by NASA. 
Source: Stanley Mandeles and Ernest C. Woods 
of University of California 
under contract to 
Headquarters, NASA 
(HQN- 10055) 
Brief 67-10395	 ,	 Category 04


Large volume continuous counterflow dialyzer has high efficiency

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