Abstract
This paper introduces the determination of trace hydrogen in gases by gas chromatography method. The determination involves several steps including sample collection, sample treatment, column selection, instrumentation and data analysis. As this procedure is a sensitive quantitative analytical method, it needs to be performed carefully and accurately. The results of this determination methods can used for comparison among different gas samples, providing more accurate information about the content of trace hydrogen in the gas.
Introduction
Hydrogen is a reactive gas, which is widely used in industrial processes. Recently, its uses have set off a revolution to develop many new technologies, ranging from hydrogen fuel cells to hydrogen-powered cars. Thus, it is important to accurately analyze the content of trace hydrogen in gases. The traditional wet analysis method is not accurate and time consuming, while gas chromatography (GC) method can be used for accurately and rapidly determine the concentration of trace hydrogen in gases.
Sample collection
The sample collection method mainly includes several steps, such as sampling location selection, sample collection and sample preparation. First of all, the sampling point shall be selected properly in accordance with the properties of the sample itself. Proper sampling point shall be selected such that it can represent accurately the composition of the sample. Afterwards, the sample shall be collected. In the actual sample collection process, due to the particularity of the gas sample, it is necessary to ensure the sample seal and not be polluted. The collected gas sample can be directly passed into the gas chromatography device for testing, or it can be pre-treated for further analysis.
Sample treatment
In many cases, the sample needs to be pre-treated before being injected into the instrument for analysis. Before treating the sample, the following points should be clarified in advance: 1. The amount of pollutant in the sample. 2. The amount of sample that need to be tested. 3. The suitable temperature range and detection range of the test instrument. 4. The sample concentration and sample concentration range, etc. In order to improve the accuracy of the results, the sample shall pass through the temperature, liquid-gas-solid exchange and other process to ensure the sample is in the required condition, before being injected into the analytical instrument.
Column selection
The selection of column is an important part of gas chromatography process. Different columns have different characteristics which can affect the chromatographic peak shape and peak area. Hence, the appropriate selection of column has great influence on the collection of chromatographic data. Generally, short capillary column or packed columns can be used when determining trace hydrogen in gases. The short capillary columns are preferred due to their overall performance, while the packed columns have good repeatability.
Instrumentation
The determination instrument used in determining trace hydrogen in gases through gas chromatography is an gas chromatography device. This device typically includes the following components: sample injection port, oven, column, detector and data system. The sample injection port is responsible for injecting sample into the instrument and separating the sample, which is then heated in the oven and passed through the column, where the separation of the sample components is taken place. After separation, the components are detected by the detector and then the data is recorded in the data system.
Data analysis
Data analysis is the last step for determining trace hydrogen in gases. After the sample is separated and detected, the data needs to be collected, staged and analyzed. The instrument can provide valuable data such as chromatographic peaks, sizes and shapes, and their associated heights is used to calculate their corresponding integrals, area ratios and peak quantities. The analysis of these data can determine the trace hydrogen in the sample.
Conclusion
In this paper, we have studied the determination of trace hydrogen in gas by gas chromatography method. In this determination, the operation steps includes sample collection, sample treatment, column selection, instrument operation and data analysis. With the gas chromatography method, the determination of trace hydrogen in gas can be accurately and quantitatively measured, which can provide the basis for the understanding of its content in various gases.
