UOP 981 Standard Test Method for Determination of Nitrogen in Liquid Hydrocarbons by Oxidative Combustion with Chemiluminescence Detection

The UOP 981 standard outlines the test method for determining nitrogen in very light liquid hydrocarbons using oxidative combustion followed by chemiluminescence detection. This method is applicable to highly volatile samples, such as pentane, which cannot be handled properly at room temperature. Through the use of a cooled sampling system even highly volatile samples can be dosed safely and completely, thus ensuring high safety and reliable results. The standard covers nitrogen concentrations ranging from 30 to 600 ng/g (mass-ppb). For samples containing more than 600 ng/g of nitrogen, alternative methods such as ASTM D4629, D6069, and D7184 are recommended. The parameter of interest is the total nitrogen content, which is crucial for assessing the purity and quality of liquid hydrocarbons.

Nitrogen compounds can significantly impact the quality and performance of these hydrocarbons, especially in industrial applications where purity is critical. The total nitrogen content is a sum parameter including all organically bound nitrogen present in the sample, providing a complete picture of nitrogen contamination. This is essential for ensuring that the hydrocarbons meet the required specifications for further processing in various industrial processes, thus catalyst poisoning and formation of undesired amine-byproducts is prevented.

The oxidative combustion ensures the quantitative digestion of nitrogen compounds to nitrogen oxides (NOx), which are converted to NO. Detection principle used is the chemiluminescence, a technique that is highly sensitive and provides accurate and consistent results, both are crucial for maintaining the quality and safety in processing of liquid hydrocarbons. The method's ability to detect ultra-low levels of nitrogen compounds makes it particularly valuable for industries that require literally nitrogen-free hydrocarbons.

In summary, UOP 981 is a crucial standard for determining nitrogen in very light volatile liquid hydrocarbons, which cannot be analyzed without cooled sample supply systems. 

Analytik Jena has over 20 years of experience in chemical analysis specifically for refineries and the petrochemical industry. With the elemental analyzers of the multi EA 5100 and compEAct series, we offer high-quality analyzers that meet the nitrogen determination requirements of UOP 981. The compEAct's ease of operation and astonishingly short analysis time enables it to greatly increase your throughput rate. The multi EA 5100, a CNSX elemental analyzer delivers optimal measurement results regardless of the matrix type, thanks to the temperature-controlled dosing systems and innovative technologies.

Sources

• UOP 981 - Standard Test Method for Determination of Nitrogen in Liquid Hydrocarbons by Oxidative Combustion with Chemiluminescence Detection