Nitrogen and on-site gas generators
Nitrogen, for those who don’t know, is an inert gas meaning it is not very reactive with other elements and chemicals. Nitrogen is highly abundant, accounting for around 78% of the earth’s atmosphere meaning we breathe in more nitrogen than any other element every day.
Atomic number 7, nitrogen was discovered in 1772 by Scottish physician, Daniel Rutherford. His discovery occurred when he removed oxygen and carbon dioxide from air and, therefore, demonstrated that the remaining gas could not support living organisms or combustion.
Since discovery, nitrogen gas has been used for a variety of important functions. Its inertness means it provides important protection for industries where oxidation is not desirable such as food packaging, reducing fire hazards, manufacturing of stainless steel, wine bottling, chemical analysis and, in particular LC-MS and Gas Chromatography.
Chromatography is defined as the separation of substances and a large number of labs conducting gas chromatography (GC) and LC-MS use nitrogen because it is inert, cheaply available and can even be generated from compressed air. Its inertness is the reason that gaseous nitrogen is highly desirable for GC and Mass Spectrometry, since it will not react with analytes, however, for GC applications it does suffer from having a poor image when compared with helium and hydrogen because of its relatively low optimal velocity. Nevertheless, more and more labs are beginning to see the potential for nitrogen to supply their GC with carrier gas. This tends to be suitable only for particular applications and GC usage but for these particular purposes nitrogen can be an extremely attractive proposition.
Nitrogen use in the lab
Nitrogen has been used in laboratory analysis for decades. In the past, labs were required to have their nitrogen gas supply delivered in cylinders or in bottles from their closest nitrogen plant, which for some labs could be some distance away. These cylinders or bottles would then supply a chromatography instrument, or perhaps a detector in the case of GC, allowing the lab to carry out its analysis.
However, for most mass spectrometers a high volumes of gas is required meaning cylinders or bottles would be consumed in a matter of days, primarily when using LC-MS. This can lead to the regular interruption of analysis and inconvenience of switching over cylinders for analysis to continue. Furthermore, cylinders and bottles deliver inconsistent purity when they reach the lower end of their capacity as contaminants can enter the empty space in the cylinder and mix with the nitrogen. These impurities can have an impact on the integrity of analysis as they can react with the sample.
There is an alternative for nitrogen cylinders, an on-site nitrogen generator. A nitrogen gas generator not only removes the hassle of having to change over cylinders, it provides an uninterrupted supply of gas at a consistent purity. This consistency is generated using one of two technologies, namely, Pressure Swing Adsorption (PSA) and membrane nitrogen.
Peak Scientific on-site nitrogen generators
On-site gas generation is also a safer solution than using cylinders. Staff are not required to carry or transport heavy cylinders around the laboratory or facility. There are also cost benefits as on-site nitrogen gas production reduces the administrative burden of ordering cylinders (raising Purchase Orders and scheduling deliveries), paying delivery fees and fluctuating costs from month to month, as the market price of nitrogen is subject to supply and demand volatility. Also to be considered are the environmental benefits of not having continuous deliveries of gas and the production of the gas itself at a nitrogen plant requires vast amounts of energy consumption.
The landscape of laboratory nitrogen gas supply has been modernised with the introduction of N2 generators bringing on-site gas generation to labs. Thousands of labs around the world have upgraded to this more efficient method of supplying gas to their LC-MS and GC applications. Those who are yet to do so should be looking to update their lab in the near future as the uncertainty of bulk gas supply could leave them uncompetitive and inefficient.