Determination of Ethylene Glycol and Propylene Glycol in New and In-Service Engine Oil using the PerkinElmer GC Platform
APPLICATION NOTE
Gas Chromatography
AUTHORS
Cory Schomburg, Ph.D., PerkinElmer, TX, USA
Vijay Veeraiyan, PerkinElmer, Mumbai, MH, India
Sagar Atugade, PerkinElmer, Mumbai, MH, India
Manny Farag, PerkinElmer, Shelton, CT, USA
Abstract
Glycol contamination of in-service lubricants generally results in increased viscosity of the fluid that then leads to several problematic issues such acid formation, additive precipitation, filter plugging and others. Detection of glycol in in-service fluids has traditionally relied on lengthy extraction processes and analysis by GC (ASTM D4291). A faster, cleaner method of analyzing glycol contamination in in-service lubricants can be done following ASTM D7922. In this method a derivatizing agent is added to neat oil then tested using a headspace analyzer. This application note presents an ASTM D7922–based gas chromatographic method for the determination of ethylene glycol and propylene glycol in lubricating oils using the PerkinElmer GC system. This approach enables sensitive, accurate, and reproducible analysis of glycol-in-oil contamination while minimizing matrix interference, demonstrating the suitability of the GC2400 for routine oil condition monitoring applications.
Why the PerkinElmer GC 2400™ is the Smarter Choice for GOIL analysis
• Delivers stable and reproducible GC performance for a highly method-sensitive ASTM D7922 workflow
• Ensures reliable EG/PG chromatography with minimal carryover and matrix impact
• Supports high-throughput GOIL testing with consistent QC and reduced downtime
• Integrated Data Management: Simplicity Chrom™ CDS ensures data integrity, traceability, and automated reporting, supporting consistent data processing and quantitation for glycol analysis in in-service oil samples
Introduction
The presence of ethylene glycol (EG) and propylene glycol (PG) in in-service lubricants is a strong indicator of antifreeze coolant leakage into the crankcase of internal combustion engines. Such contamination can lead to accelerated oil degradation, corrosion, sludge formation, and increased engine wear, making early detection of glycol-in-oil (GOIL) contamination critical for effective condition monitoring and preventive maintenance programs.
Several analytical approaches are available for the determination of glycols in lubricating oils. Traditional colorimetric and infrared-based techniques are commonly used for screening purposes due to their simplicity; however, these methods are often subjective, limited in sensitivity, and unsuitable for accurate quantification, particularly at low contamination levels. Gas chromatography (GC) offers superior selectivity and quantitative capability, but direct analysis of glycols presents analytical challenges due to their low molecular weight, low volatility, and high polarity. As a result, poor peak shape, adsorption effects, and carryover are frequently observed.
Direct injection of in-service engine oil into a gas chromatograph further complicates the analysis by introducing high-molecularweight and non-volatile oil components into the inlet and column. This can lead to extended run times, reduced column lifetime, and low sample throughput, as high-boiling matrix components must elute before subsequent injections. An ASTM standard has been used to determine the amount of glycol in new and in-service fluids (ASTM D4291) using gas chromatography. This method requires a lengthy extraction process with water followed by GC analysis of the water layer. Complications with the extraction frequently arise due to the additives within the lubricant making this method difficult.
ASTM Method D7922 addresses these challenges by employing derivatization approach to convert ethylene glycol and propylene glycol into more volatile and less polar derivatives suitable for gas chromatographic analysis. This approach enables efficient separation and accurate quantification of EG and PG while minimizing matrix-related interferences and protecting the chromatographic system from contamination by heavy oil components.
In this application note, an ASTM D7922–based method is demonstrated using the PerkinElmer GC2400 system for the determination of ethylene glycol and propylene glycol in lubricating oils. The method provides a robust, sensitive, and high-throughput solution for routine GOIL analysis, delivering reliable performance for oil condition monitoring laboratories and industrial users. The same validated workflow is fully supported on the Clarus® Nova GC platform, enabling laboratories to achieve comparable performance within a modern, integrated system.
Instrumentation
Analysis was performed using the PerkinElmer GC 2400™ System equipped with a Flame Ionization Detector (FID). The GC 2400 System was configured with a capillary split-splitless injector and a PerkinElmer Elite 5 column. Data acquisition and processing were performed using Simplicity Chrom™ CDS software.
Experimental
Standard and calibration curve preparation:
Ethylene glycol and propylene glycol standards were procured from an authorized supplier of the Merck Group. Stock solutions (10,000 ppm) of each glycol were prepared using glycol-free fresh engine oil as the base matrix. Approximately 1.00 g of ethylene and propylene glycol was weighed and diluted with 99.00 g of glycol-free engine oil to obtain the stock solutions.
Due to the immiscibility of glycols in oil, mild heating combined with mechanical stirring was applied to achieve proper dispersion and homogenization within the oil matrix.
A 1 M PBA solution was prepared by dissolving 1.22 g of phenyl boronic acid (PBA) in 10 mL of methyl ethyl ketone (MEK). In this method, glycols present in the lubricant were derivatized with PBA to form volatile derivatives, enabling efficient chromatographic analysis.
Calibration levels of 100, 200, 500, and 1000 ppm were prepared from above standard stock solution(10000PPM). For each level, 100 µL of the glycol-in-oil standard was transferred into a 20 mL headspace vial using a positive displacement pipette. Subsequently, 50 µL of the PBA reagent was added to the vial.
Sample preparation:
All samples were homogenized thoroughly prior to analysis. 100 µL of the sample was transferred into a 20 mL headspace vial using a positive displacement pipette, to this solution 50 µL of PBA reagent was added. Then the vial was capped and crimped.
Method
The acquisition method and analytical conditions are summarized in Table 1; these parameters were optimized to ensure complete derivatization, minimal carryover, and reproducible peak area response.
The consumables listed in Table 2, identified by PerkinElmer part numbers, were selected to ensure reliable glycol derivatization, separation, and quantitation on the GC 2400 System. Use of the specified injector components, Elite-5 column, derivatization reagent, standards, and sample handling supplies supports consistent chromatographic performance and reproducible results when analyzing complex engine oil matrices.
Results and Discussion
Calibration standards having both EG and PG at 0, 100, 500, 1000 and 2000 ppm were tested for quantitative analysis of engine samples. The correlation coefficient for both, the EG and PG calibration, were better than 0.9998 showing excellent linearity of the calibration.
A set of 71 engine samples believed to contain glycol contamination was received for testing by GC. The results from this sample set show 25 engine oil samples were positive for glycol contamination in the oil. From the samples that tested positive, 6 were found to have concentration values above the highest calibration point (2000 ppm) and 5 of the sample concentrations were below the lowest calibration point (100 ppm). Unexpectedly, several of the samples also tested positive for propylene glycol in the engine oil.
Glycol in Engine Oil Sample Set
A total of 71 engine oil samples were received and analyzed for glycol contamination. Calibration was performed prior to sample analysis, and quality control (QC) at 750 ppm was tested at both the beginning and end of the batch to ensure analytical reliability. Out of the 71 samples, 25 samples (35%) tested positive for glycol, indicating a notable level of contamination within the sample set, while the remaining 46 samples (65%) showed no detectable glycol presence.
Among the glycol-positive samples, 14 results fell within the calibrated quantification range of 100–2000 ppm, allowing for accurate measurement. However, 6 samples exceeded the upper calibration limit (>2000 ppm), indicating severe contamination levels and requiring dilution and reanalysis for precise quantification. Additionally, 5 samples were detected below the lower calibration limit (<100 ppm), suggesting trace-level contamination; these results are considered semi-quantitative and should be reported as “detected below limit.” details mentioned in table no 4.
Conclusion
The glycol in oil test following ASTM D7922 represents a rapid method for identification and quantification of glycol contamination in lubricants. In this application, the glycol in an oil is derivatized using phenyl boronic acid to create a reaction product that can be tested in the vapor phase. The vapor phase of the headspace vial is sampled and chromatographed under isothermal oven conditions. A calibration plot of ethylene and propylene glycol standards show good linearity from 100 to 2000 ppm allowing for accurate quantification of glycol in engine oils.
References
1. ASTM D7922-21: Standard Test Method for Determination of Glycol for In-Service Engine Oils by Gas Chromatography.
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