Monoethylene glycol (MEG) is employed before further processing of natural gas to remove water content. Glycol degradation may take place when high temperatures are applied as part of the process, forming formic, acetic, and glycolic acids.
These are unwanted reactions as the acids formed are corrosive in nature. This article discusses the application of ion-exclusion chromatography with conductivity detection following inverse suppression to determine the presence of organic acids in MEG.
Sample
Monoethylene glycol
Sample preparation
Metrohm inline ultrafiltration.
Columns
| Metrosep Organic Acids - 250/7.8 |
6.1005.200 |
| Metrosep Organic Acids Guard/4.6 |
6.1005.250 |
Solutions
| Eluent |
1.0 mmol/L sulfuric acid |
| Suppressor regenerant |
100 mmol/L lithium chloride |
| Rinsing solution |
STREAM |
Analysis
Conductivity detection following the inverse suppression
Parameters
| Flow rate |
0.5 mL/min |
| Injection volume |
20 μL |
| Pmax |
7 MPa |
| Recording time |
25 min |
| Column temperature |
50 °C |
Instrumentation
| 930 Compact IC Flex Oven/ChS/PP/Deg |
2.930.2360 |
| IC Conductivity Detector |
2.850.9010 |
| 858 Professional Sample Processor |
2.858.0020 |
| MSM Rotor A |
6.2832.000 |
| Adapter sleeve for Suppressor Vario |
6.2842.020 |
| IC equipment: Inline Ultrafiltration |
6.5330.110 |
Results
| |
Concentration [mg/L] |
| 1 |
Glycolic acid |
9.6 |
| 2 |
Formic acid |
31.1 |
| 3 |
Acetic acid |
753.3 |
| 4 |
Propionic acid |
42.3 |
| 5 |
Carbonic acid |
n.q. |
| 6 |
unknown |
n.q. |
About Metrohm
At Metrohm is one of the world’s most trusted manufacturers of high-precision instruments for chemical analysis. Metrohm was founded in 1943 by engineer Bertold Suhner in Herisau, Switzerland. Today, Metrohm is represented in 120 countries by subsidiaries and exclusive distributors. The global Metrohm Group also includes the Dutch companies Metrohm Applikon and Metrohm Autolab, manufacturers of online analyzers and instruments for electrochemical research, respectively. Recently, the Metrohm Group was joined by Metrohm Raman, a leading manufacturer of handheld Raman spectrometers.
Metrohm is the global market leader in analytical instruments for titration. Instruments for ion chromatography, voltammetry, conductivity, and stability measurement make the Metrohm portfolio for ion analysis complete. Instruments for Near-infrared and Raman spectroscopy are another, strongly growing segment of the Metrohm portfolio.
Metrohm is a problem solver, both in the laboratory and within the industrial process. To this end, the company offers their customers complete solutions, including dedicated analytical instrumentation as well as comprehensive application know-how. More than 30% of the company’s employees at the Metrohm international headquarters in Herisau work in R&D.
Metrohm has been owned 100% by the non-profit Metrohm Foundation since 1982. The Metrohm Foundation, which does not exert any influence on the company’s business operations, sponsors gifted students in the natural sciences, supports charitable and philanthropic purposes and, above all, ensures the independence of the company.
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