To prevent samples containing foreign matter from poisoning the gas chromatographic columns, a pre-filter insertion is placed in the injection port. The packing becomes a variable reactant, for example, acids are removed by using an alkaline liquid

Robertson, M. D.

Welz, E. A.

English

NASA Technical Reports Server

December 1969	 Brief 69-10788 
NASA TECH BRIEF 
NASA Teëh 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. 
Gas Chromatograph Injection Port Protective Device 
The problem: 
To prevent samples containing foreign materials 
from poisoning gas chromatograph columns, and to 
allow chromatographic analysis to be performed on 
such samples. 
The solution: 
The column is protected by inserting a pre-filter into 
the chromatograph injection port, to trap and hold 
undesirable species. Packing of the insert is similar to 
that of a wet chromatographic column in which the 
liquid phase becomes a variable reactant. This permits 
selective retention of the undesirables. For example, 
acids in a sample may be removed by using an alkaline 
liquid. 
How it's done: 
In attempting to use gas chromatography to analyze 
mixtures of hydrazine, monomethyl hydrazine, hydra-
zine nitrate, and water, it was found that the chroma-
tographic column was rapidly poisoned by the deposi-
tion of hydrazine nitrates and the buildup of acidic 
salts. 
The first problem was solved by reacting a small 
portion of the sample with sodium methoxide to liber-
ate hydrazines from any free radicals present.
The second problem was solved by installing an 
on-column inlet modified to hold an exchangeable 
insert, which was packed with Polyethyleneimine 
(PEI) on a standard filler material. PEI is known to 
be an efficient trap for acidic and highly polar material; 
These techniques have increased the lifetime of the 
chromatographic column to three months of continuous 
service. 
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B69-10788 
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: Edward A. Welz and Marston D. Robertson of

North American Rockwell Corporation

under contract to

Marshall Space Flight Center

(MFS-18585) 
Category 03 
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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Gas chromatograph injection port protective device

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