Stability test and improvement of hydrogen analyzer with trace reduction detector

Area of Science:

• Analytical Chemistry
• Environmental Science

Background:

• Accurate detection of low hydrogen concentrations is crucial for various applications.
• Previous analyzers faced challenges with impurities and dilution gases like nitrogen.
• Trace reduction detectors with mercuric oxide beds were employed.

Purpose of the Study:

• Evaluate the performance of a previously developed hydrogen analyzer.
• Identify and resolve issues affecting the stability and accuracy of low-concentration hydrogen measurements.
• Improve the analyzer's robustness, particularly when using nitrogen as a dilution gas.

Main Methods:

• Utilized a carrier gas purifier and low-temperature separation column.
• Employed a trace reduction detector with a mercuric oxide bed.
• Introduced an MS-5A separation column and thermal conductivity detector with an "after-cut method" to remove nitrogen.

Main Results:

• The original analyzer showed stable peak measurements (RSD < 10%) with a linear response to hydrogen concentration.
• Retention time instability was observed, linked to nitrogen dilution gas.
• The modified analyzer using the "after-cut method" demonstrated stable measurement of infinitesimal hydrogen concentrations, unaffected by nitrogen.

Conclusions:

• The "after-cut method" effectively resolves retention time issues caused by nitrogen dilution gas.
• The enhanced analyzer provides stable and accurate detection of very low hydrogen concentrations.
• This improved analyzer is suitable for applications requiring precise hydrogen measurement in the presence of nitrogen.