In the presence of dissolved oxygen in the water inside a pipeline, the oxygen attacks the steel to form iron oxides. To prevent this, corrosion inhibitors are added to the crude oil streams. These chemicals are amines-based that form a film to coat the steel and prevent it from contacting the oxygen. Amines residuals should be monitored in the system and this is classically done by liquid-liquid extraction (LLE) of amines followed by colorimetric determination using spectrophotometry.
In this work, solid phase microextraction (SPME), a novel extraction technique that uses no solvent, was used as a sample preparation technique to isolate the amines from the complex sample matrix and then the gas chromatography (GC) system was used for separation and quantification of amines. A flow-through system was used to simulate the process of flowing streams in pipelines during oil production.
A method was developed to determine amines residuals at the lowest detection limit possible at the optimized conditions such as solution pH, ionic strength, and sand contents. It was found that residuals can be determined as low as 1ng/mL using the GC system equipped with a flame ionization detector (FID). This method was developed in the lab using a model to simulate the flowing streams and containing synthesized waste water.
This method is an environmental friendly technique that will minimize the use of hazardous solvents and therfore the need for the proper disposal of them. Also it does not require pretreatment steps of samples or many reagents to be used in the extraction process of amines residuals. Finally, it will provide more precise results in a timely manner for better and quicker actions.