To determine moisture content of soils rapidly and conveniently extract moisture with methanol and determine water content of methanol extract by gas chromatography. Moisture content of sample is calculated from weight of water and methanol in aliquot and weight of methanol added to sample

Carle, G. C.

Merek, E. L.

English

NASA Technical Reports Server

December 1973	 B73-10503 
NASA TECH BRIEF 
Ames Research Center	 -dr 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
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be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Soil Moisture by Extraction and Gas Chromatography 
The problem: 
To determine the moisture content of soils rapidly 
and conveniently by gas chromatography. 
The solution: 
Extract the moisture with methanol and determine 
the water content of the methanol extract by gas 
chromatography. 
• How it's done: 
A 1.000-g sample of soil in a 16- x 100-mm screw-
cap test tube is treated with 8.00 ml of chromatog-
raphic-grade methanol; depending on temperature, 
the volume of methanol usually has a weight of 2.346 
to 2.355 g. A second tube containing the same volume 
of methanol is used as reference. The tubes are 
capped tightly and agitated for 30 minutes on a re-
ciprocating shaker. The tubes are then centrifuged at 
1200 rpm (16-cm radius) for 5 minutes. 
A one-microliter aliquot of the supernatant liquid 
is then analyzed for water by gas chromatography, 
using a column packed with 50- to 80-mesh porous 
polymer beads. The column is maintained at 1250C, 
the helium flow at 150 ml/min, the detector oven 
temperature at 150°C, and the injection block tem-
perature at 200°C. The gas chromatograph is cal-
ibrated with mixtures of water in methanol. 
Moisture content of the sample is calculated from 
the weight of water and methanol in the aliquot and 
the weight of methanol added to the sample:
(water in aliquot) x (methanol added to soil) 
(methanol in aliquot) 
Higher moisture contents are obtainable by this 
extraction procedure than by the customary oven-
drying method, except in the instances of organic-
rich soils where part of the measured weight loss 
may be attributed to loss of volatile organic com-
pounds. The minimum detectable quantity of water 
in a 1-4Ltl aliquot is 200 jig per gram of sample; ali-
quots of 100 1 would, of course, increase sensitivity 
proportionately if the water in the reagent methanol 
(0.05%) could be reduced proportionately. 
Reference: 
Merek, .E. L. and Carle, C. C.: The Determination 
of Soil Moisture by Extraction and Gas Chromatog-
raphy. Soil Science (late 1973). 
Note: 
No additional documentation is available. Specific 
questions, however, may be directed to: 
Technology Utilization Officer 
Ames Research Center 
Moffett Field, California 94035 
Reference: B 73-10503 
Patent status: 
NASA has decided not to apply for a patent. 
Source: Edward L. Merek and Glenn C. Cane
Ames Research Center
(ARC-10748) 
Category 04 
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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Soil moisture by extraction and gas chromatography

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