Mass spectrometer is used to measure small quantities of water present in different materials. System has been applied in measuring water and gases desorbed from microcircuitry insulation, can also be used with foods, polymeric materials, and organic solvents

Hughes, D. B.

Upchurch, B. T.

Wood, G. M.

English

NASA Technical Reports Server

August 1975	 B75-10157 
NASA TECH BRIEF 
Langley Research Center 
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 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Determination of Water Content Using Mass Spectrometry 
A new system using a mass spectrometer has been 
developed to measure small quantities of water 
present in different materials. It has been applied in 
measuring water and gases desorbed from less-than-
1-g samples of Teflon/FEP (fluorinated ethylene-
propylene copolymer) insulation. The insulation is 
used in microcircuitry. The system can also be used 
with foods, polymeric materials, and organic solvents. 
As shown in the illustration, the system includes a 
Pyrex sample cell. The cell is connected in-line with a 
dry nitrogen gas source and with an electrically-
heated, 0.010-in. (0.3-mm) stainless-steel capillary, 
approximately 25 in. (63.5 cm) long, leading to the 
mass spectrometer inlet. The cell may be maintained 
at a constant elevated temperature or may be 
temperature programed to approximately 3500 C. The 
temperature is continuously monitored with a 
thermocouple mounted inside the cell.
A weighed sample is introduced into the cell, and 
the evolved gas is swept into the mass spectrometer 
leak cavity by the dry nitrogen gas at approximately 
25 cm 3/min. The data are obtained by recording ion 
current on an X-Y plotter as a function of time or 
temperature, with the mass spectrometer tuned to 
monitor a single mass. The ion current is simultane-
ously measured with an integrating digital voltmeter 
to obtain a quantitative measure of the total water or 
gas evolved. This value is determined by dividing the 
total number of counts by the instrument response. 
The calibration procedure to obtain the instrument 
response is as follows: Samples of reagent-grade 
Valve 
To
_T^ 
Vacuum 44
Pressure Transducer Ion Source 
Dry N2 T I I Heated 1
Sample 
Cell
-
Iji i 
Flow Leak A 
Meter Cavity 
Capillary
. 
110 Vac Check Valve Ion 
Amplifier 
Y i
Axis
	 ITirne
CollectorThermostatic 
Control Axis Integrating 
Plotter I Digital Voltmeter
[] Water Analysis System
(continued overleaf) 
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 Stales 	 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. 
https://ntrs.nasa.gov/search.jsp?R=19750000157 2020-03-19T20:26:09+00:00Z
disodium tartrate dihydrate weighing 10 to 20 mg are 
introduced into the cell. The cell is subsequently 
programed to 180 0 C or is operated isothermally at 
150° C, and the data are obtained as described above. 
Since the sodium tartrate contains 15.66 percent 
water by weight, these measurements yield instrument 
response in counts/mg H20. 
The new method can measure water content over a 
range of milligrams to micrograms with an apparent 
detection limit of approximately 0.3 yg. Measurement 
precision, obtained from the determination of total 
water evolved from 10-mg to 20-mg samples of barium 
chloride dihydrate (14.75 percent water by weight), is 
of the order of 1 percent of the determined value. For 
the part-per-million concentrations measured from 
Teflon, the relative precision is better than 15 percent 
(standard deviation). The time required to obtain the 
data is approximately 2 to 4 minutes.
Note:. 
Requests for further information may be directed 
Technology Utilization Officer 
Langley Research Center 
Mail Stop 139-A 
Hampton, Virginia 23665 
Reference: B75-10157 
Patent status: 
NASA has decided not to apply for a patent. 
Source: G. M. Wood
Langley Research Center and
B. T. Upchurch of
Old Dominion University and

D. B. Hughes of
E. I. du Pont de Nemours and Co.

under contract to

Langley Research Center
(LAR-11774)
. 
Categories: 04 (Materials) 
05 (Life Sciences) 
B75-10157
	 02 (Electronics Systems)


Determination of water content using mass spectrometry

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