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Updated: May 28, 2026
10:44
Clean Sampling and Analysis of River and Estuarine Waters for Trace Metal Studies
Published on: July 1, 2016
A dynamic gravimetric standard for trace water
P J Brewer1, B A Goody, P T Woods
1National Physical Laboratory, Analytical Science Division, Teddington, Middlesex TW11 0LW, United Kingdom. paul.brewer@npl.co.uk
The Review of Scientific Instruments
|November 4, 2011
Summary
A new system generates traceable water vapor reference standards from 5 to 2000 nmol/mol with ±2% uncertainty. This system shows excellent comparability with international metrology institutes.
Area of Science:
- Metrology
- Analytical Chemistry
- Environmental Science
Background:
- Accurate water vapor reference standards are crucial for environmental monitoring and industrial processes.
- Existing methods for generating trace levels of water vapor can be complex and challenging to calibrate.
Purpose of the Study:
- To develop and validate a novel system for generating traceable reference standards of water vapor at trace levels.
- To achieve high accuracy and comparability with international standards.
Main Methods:
- Development of a system utilizing continuous mass loss measurements from a permeation device.
- Integration of a dilution system employing an array of critical flow orifices.
- Accurate measurement of mass loss and precise control of dilution ratios.
Main Results:
- Successful generation of traceable water vapor reference standards in the range of 5 to 2000 nmol/mol.
- Achieved an estimated relative expanded uncertainty of ±2% for most generated amount fractions.
- Demonstrated excellent comparability with National Metrology Institutes in an international comparison.
Conclusions:
- The developed system provides a reliable and accurate method for generating trace-level water vapor standards.
- The system's performance is validated through international comparisons, confirming its metrological traceability and comparability.
- This advancement supports accurate environmental measurements and industrial applications requiring precise water vapor control.
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