D5762-24 – Standard Test Method Technical Guide

📐 Test Method Scope and Significance

This test method, designated D5762-24, covers the determination of nitrogen in liquid hydrocarbons, including petroleum process streams and lubricating oils, in the concentration range from 40 µg/g to 10,000 µg/g nitrogen. For light hydrocarbons containing less than 100 µg/g nitrogen, Test Method D4629 is recommended. The values stated in SI units are standard, and this standard does not address all safety concerns, requiring user responsibility for safety practices.

This test method is significant because nitrogen compounds can contaminate refinery catalysts and are the most difficult compounds to hydrogenate. The nitrogen content remaining in hydrotreater products measures the effectiveness of the hydrotreating process. In lubricating oils, nitrogen concentration indicates the presence of nitrogen-containing additives. This method is intended for use in plant control and research.

⚙️ Apparatus and Test Procedure

The apparatus includes a boat inlet system that can be sealed to the inlet of the combustion tube and swept with inert gas. Boats are fabricated from platinum or quartz. To aid quantitative liquid injection, it is recommended to add a small piece of quartz wool or suitable equivalent to the boat. The boat drive mechanism should fully insert the boat into the furnace tube inlet section and advance and withdraw the sample boat at a controlled and repeatable rate.

The test procedure involves placing a hydrocarbon sample on the boat at room temperature. The sample and boat are advanced into a high-temperature combustion tube where nitrogen is oxidized to nitric oxide (NO) in an oxygen atmosphere. The NO contacts ozone and is converted to excited nitrogen dioxide (NO₂). The light emitted as the excited NO₂ decays is detected by a photomultiplier tube, and the resulting signal measures the nitrogen content in the sample.

📊 Key Specifications and Performance Data

The method covers a concentration range of 40 µg/g to 10,000 µg/g nitrogen. Referenced standards include D405