For those who do not know it, nitrogen is an inert nitrogen gas. It is therefore not very reactive in contact with other elements and chemicals. Nitrogen gas is very abundant since it represents about 78% of the atmosphere. This means that we breathe more nitrogen than any other element on a daily basis. Bearing the atomic number 7, nitrogen was discovered in 1772 by the Scottish physician Daniel Rutherford, who removed oxygen and carbon dioxide from the air, proving that the remaining nitrogen gas could not ensure survival living organisms or burning. Therefore, nitrogen gas has been used in various important applications. Its inertia allows it to offer essential protection to industries that must avoid any oxidation, such as food packaging, fire risk reduction, stainless steel production, wine bottling, chemical analysis, including gas chromatography (GC) and liquid chromatography-mass spectrometry (LC-MS). Chromatography is a method of separating substances. Many laboratories use GC and LC-MS with nitrogen because this inert and affordable gas can be generated from compressed air. As an inert gas, nitrogen in the gas phase is very popular with gas chromatography and mass spectrometry applications because it does not react with the analyses. However, it is preferred to use helium and hydrogen for GC applications because of its relatively low optimal velocity. A growing number of laboratories are beginning to realize the potential of nitrogen as a carrier gas for GC applications. It is certainly suitable only for specific techniques, including gas chromatography, for which it nevertheless represents a particularly interesting solution.

The use of nitrogen gas in the laboratory

Laboratories have been performing analyzes using nitrogen gas for decades. In the past, laboratories had to obtain nitrogen in the form of bottles from the nearest plant, which in some cases could be very far away. Thus they provided the supply of chromatography instruments or detectors for the GC application to perform analyzes. Since most mass spectrometers require a large volume of gas, the laboratories consumed all the bottles in a few days, especially if they used the LC-MS technique. They had to replace the bottles regularly and to do this, interrupt analyzes. In addition, the purity of the bottles gas is inconsistent because contaminants fill the empty space left by the gas consumed and mix with nitrogen gas. Impurities can react with the sample and interfere with analyzes. It is possible to replace the nitrogen bottles with a nitrogen generator on site, which ensures a gas of constant purity continuously, without replacement of bottles. Consistency of supply is ensured by the use of modulated pressure adsorption or membrane separation of nitrogen. On-site nitrogen gas generators are a safer solution than bottles. Staff should no longer transport or move heavy cylinders of gas through the laboratory or center. On-site nitrogen production also has economic benefits as it reduces the administrative burden associated with bottle orders (purchase order creation and delivery planning), delivery costs and price fluctuations caused by volatility, supply and demand from one month to the next. On-site gas generation has a reduced environmental impact compared to the considerable energy consumption caused by continuous plant production and bottle deliveries. The arrival of nitrogen generators has modernized the world of laboratories, which now produce their own gas on site. Thousands of labs have already turned to this more efficient method of supply for LC-MS and GC applications. Those who have not yet done so should rectify the situation as soon as possible so that uncertainties related to the supply of bulk nitrogen gas do not affect their competitiveness and efficiency.