The nitrogen/hydrogen generator leader teaches you how to make a simple 7-step process. How does hydrogen successfully replace helium?

Air source

The price of radon is rising. According to reports, the price of radon has increased several times in some areas between 2013 and 2015. In addition to the price, even in some areas it is not possible to ensure the supply of helium, which has led more and more laboratories to convert helium into hydrogen. Hydrogen Generator: Precision Hydrogen Trace provides 99.9999% purity of carrier gas grade hydrogen and is considered an extremely safe source of hydrogen to ensure column life and the highest level of analytical quality.

Pipe supply: The hydrogen line should use a new stainless steel line or an analytical grade copper tube. If you previously used helium to supply the GC, the tubing needs to be replaced. Since the time has been used for a long time, there will be accumulation of sediment on the inner wall of the pipe, and hydrogen will bring it out, resulting in a high background signal for a long time.

2. Hydrogen safety

Safe use of hydrogen: Because hydrogen is a flammable gas, the health and safety of the laboratory cannot be ignored, so many laboratories limit the use of hydrogen cylinders.

LEL: The lower limit of explosion (LEL) of hydrogen in air is 4%. Therefore, a cylinder containing 8000 L of hydrogen leaks into a relatively sealed laboratory, and it is very likely that the lowest concentration of the explosion can be reached, creating an explosive environment without any indication. In addition to the risk of gas leakage, it is a potential health and safety hazard to move a bulky can when changing cylinders. Gas Generator: The Peak Precision hydrogen generator is an ideal source of hydrogen. It can supply ultra-high purity hydrogen to multiple GCs for carrier gas and detection gas at a flow rate of several hundred milliliters with low pressure. Precision Hydrogen Generators have a number of safety features that detect any internal or external leaks from the generator and GC and then automatically shut down.

Leak detector: Peak can also provide a hydrogen detector in the column oven. Once a significant hydrogen leak is detected in the oven, the generator will automatically shut down.

3. Hardware

If you plan to use hydrogen as a carrier gas, you must first check with your GC supplier. When using hydrogen, each manufacturer must test it, as the model you are using may have some special settings. When necessary, GC-MS is likely to replace hardware.

Vacuum pump: If you are using GC-MS, it is important to ensure that your vacuum pump is adequate to maintain the vacuum environment of the air supply. With a lower molecular weight gas, the vacuum efficiency is reduced, so it must be confirmed with your GC manufacturer to ensure that your pump system can handle hydrogen carrier gas. If you are planning to purchase a new GC-MS, you must let your supplier know that you intend to use hydrogen as a carrier gas so that they can supply the right vacuum pump.

Ion source: When using hydrogen as a carrier gas to analyze analytes of certain specific components, some GC-MS manufacturers may need to upgrade the package with hydrogen or replace the components of the ion source to increase sensitivity. If you are planning to buy a new GC-MS system, please consult your supplier to select the appropriate ion source to avoid additional costs and wasted time.

4. Consumables

Columns: In standard GC, when helium is replaced with hydrogen, there is almost no need to change the settings. Using a method to translate the software, you can simulate the effect of changes in carrier gas on the carrier gas pressure and the rate of temperature rise in the oven, resulting in a revalidation method. Depending on your GC method parameters, it may not be necessary to replace a finer capillary column unless the internal pressure becomes very low when the method is switched. However, it is also advantageous to use a finer capillary column to increase the separation efficiency of hydrogen as a carrier gas. By using a thinner capillary column, the number of theoretical plates is increased, it is possible to improve efficiency and the sample can be better separated.

Inlet: The liner of the inlet should be replaced frequently to ensure that the system is free of contamination. When using hydrogen as a carrier gas, it is recommended to use a tapered liner to minimize contact with the splitter plate.

Septum: Replacing the inlet septum is a common task in GC maintenance. Regular replacement can avoid peaks and prevent contamination.

5. Method

You must confirm that your method can use hydrogen as a carrier gas. If you are using a conventional method (such as EPA, ASTM), first confirm which carrier gas is allowed. If hydrogen is allowed, do you have a working guide for the method you are interested in?

Method Translation Software: Method translation software can be obtained from a variety of resource sources and can be used to calculate GC settings when using hydrogen as a carrier gas. This will optimize your approach and explore the choice of column before you actually set up the system.

Use of chlorinated solvents: When hydrogen is used as the carrier gas for GC and GC-MS, the HCl formed by the reaction of H2 and Cl is generally considered to be a potential problem because HCl may damage the GC system. Hydrogen typically reacts with analytes or solvents, so reducing the residence time of the sample at the inlet is critical. Pulsed or splitless injections can help reduce sample residence time at the inlet and reduce the likelihood of HCl formation or reaction between hydrogen and analyte.

Injection temperature: The potential reaction between solvent, analyte and hydrogen can be reduced with the lowest possible injection temperature.

6. System settings

Column aging: When setting up a new GC system with hydrogen as the carrier gas, you need to age the column. Make sure that the end of the column is outside the GC oven to prevent hydrogen build-up in the oven and eliminate the potential for explosion.

Ion Source Bake: When you set up GC-MS, after the system is tuned or set up for a brief sample after the carrier gas, you often encounter some common performance problems. Such as a hydrocarbon-like background and a very high m/z 29 peak. Baking the ion source can quickly solve these problems and can be lowered after a night of baking background. The GC-MS manual or online technical lecture on using hydrogen as a carrier gas usually has details on how to bake your MSD.

7. Performance check

Signal-to-Noise Ratio: Comparing the results of running with helium and hydrogen can reduce the signal-to-noise ratio (2-5 times depending on the system). SIM detection with a single four-level system can further reduce the signal-to-noise ratio. Cracking method: If the ion ratio changes, it is most likely because there is too much hydrogen in the ion source. This problem can be mitigated by reducing the internal diameter of the column to reduce the flow rate of the carrier gas and thereby reducing the amount of hydrogen entering the ion source.

Peak tailing: When using hydrogen as a carrier gas, polar substances are more susceptible to peak tailing. After baking the ion source, the peak tailing phenomenon will decrease, and the peak tailing of most substances will decrease after a few days.

Background: After changing the carrier gas for a few days, the background signal will drop to a stable level.

If you want to know more, please contact BYK China:

BYK Gas Instrument Trading (Shanghai) Co., Ltd.

Room 501-502, Block E, Changtai Plaza, No. 6, Lane 2889, Jinke Road, Zhangjiang Hi-Tech Park, Pudong New Area, Shanghai

Hotline: +86 400 888 1612

Phone: +86 21 5079 1190+86 21 5079 1190

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