Introduction
Corrosion caused by organic acids is one of the biggest pain points for oil, oil refining, and car manufacturing industries. The resulting damage to industrial production installations and car engines is highly disruptive and expensive. In the most extreme cases, it can even threaten a company’s long-term success and survival.
Low molecular weight organic acids are reported to be aggressively corrosive in the refining process. The reliable determination of smaller organic acids is an essential aspect of petroleum product quality control. It requires accurate methods that are easy to establish in an industrial setting. Investigating the compounds responsible for corrosion is complex. Of the 1,000 or more different organic acids potentially present in crude oil, each possesses other characteristics that influence corrosivity.
Modern ion chromatography systems support industrial applications
Fortunately, petrol and oil-related industries can now look to ion chromatography (IC) as a promising solution. At first glance, IC appears unsuited to analyzing petroleum products, as water-immiscible samples cannot be directly injected. However, modern automated IC solutions overcome these issues and are increasingly working their way into new applications.
Putting automated IC to the test
A recent case study assessed the suitability of IC for the analysis of organic acids in diesel, oil, and oil-containing diesel samples in different ratios. Samples were diluted with 2-propanol and stored in glass autosampler vials until they were delivered to the Thermo Scientific Dionex IonPac UTAC-LP1 concentrator column. Following a nonaqueous analyte extraction and a rinse of the concentrator, the analytes were measured using a Thermo Scientific Dionex RFIC-system (e.g., the Thermo Scientific Dionex Integrion HPIC System).
Acetic acid and formic acid were identified and quantified in the single-digit mg/L range, showing high repeatability within individual days (within 2%) and across days (4% for acetic acid and 9% for formic acid). Quantitative recovery was found for different solutions, both intra-day, and inter-day.
Automated IC for the analysis of petroleum products
Formic acid and acetic acid were directly determined using IC for diesel and oil-containing diesel samples. The in-line matrix elimination step was critical to removing the hydrophobic matrix and enabling the high level of recovery and repeatability observed across different petroleum-based samples.
As matrix elimination and chromatographic analysis are automated, IC offers a practical and reliable way to investigate the properties of corrosive, low molecular weight organic acids.
You can read more about the use of modern IC systems to determine organic acids in petroleum products in this app note.
Be sure to stay tuned for future blog posts. We will be highlighting further examples of how advances in ion chromatography are taking quantitative analysis to new heights across other industries.