Space oriented, lightweight, subminiaturized gas chromatograph analyzes gas samples in a few seconds with a carrier gas flow of one milliliter per second. In extraterrestrial exploration, the system could be used with a mass spectrometer for detection of life-supporting compounds

Wilhite, W. F.

English

NASA Technical Reports Server

May 1966	 Brief 66-10182 
NASA TECH BRIEF C' 
NASA Tech Briefs are issued to summarize specific innovations derived from the U. S. space 
program and to encourage their commercial application. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Subminiaturized Gas Chromatograph Gives Fast, Efficient Analysis 
The problem: 
In gas chromatography, there are many commer-
cially available devices that, together, can analyze a 
wide range of gases. For space applications, these 
devices pose serious weight problems because of the 
large amounts of carrier gas they must dissipate in 
effecting an analysis. Additionally, it is desirable to 
analyze the gases more rapidly than the typical 5 to 
10 minutes required of prior art. 
The solution: 
A subminiaturized gas chromatograph weighing 
only 100 grams and capable of analyzing samples in 
a few seconds with a carrier gas flow of one milliliter 
per minute. 
How it's done: 
A one-microliter gas sample is injected with the 
carrier gas into a subminiaturized column (micro-
column) where the selective absorption of the con-
stituents by the column packing causes characteristic 
delays in traversal time, thus separating the constit-
uents. The column is packed with fine-grain (25-
micron) particles of uniform size that are held in 
place by electronically machined, sintered stainless-
steel plugs that allow the gas to pass through while 
retaining the particles. The small volume of gas from 
the microcolumn is passed through a subminiature 
detector that compares the conductivity of the carrier 
gas and sample with that of the carrier gas alone in 
separate chambers. Each chamber is equipped with a
platinum—rhodium thermal conductivity element hot 
wire 0.012-inch long and 10 5 -inch in diameter, each 
forming half of a ratio arm of a Wheatstone bridge. 
Chamber volume is 0.1 microliter and power drain is 
only 0.5 milliwatt. 
Notes: 
1. A microcolumn three inches long will separate 
certain compound constituents in one second with 
a carrier gas flow rate of only one milliliter per 
minute. A typical prior art column would be 10 
feet long, require a carrier gas flow rate of 60 
milliliters per minute, and require 10 minutes to 
effect the same separation. 
2. In extraterrestrial exploration, the system could be 
used with a mass spectrometer for the detection of 
life-supporting compounds. 
3. Inquiries concerning this invention may be directed 
to:
Technology Utilization Officer 
Jet Propulsion Laboratory 
4800 Oak Grove Drive 
Pasadena, California, 91103 
Reference: B66-10182 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C., 20546.
Source: W. F. Wilhite 
(JPL-735, 736, 737, and 740) 
Category 01 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States 	 will be free from privately owned rights.
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Subminiaturized gas chromatograph gives fast, efficient analysis

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