Ethylene glycol in in-service motor oil is an indication of antifreeze coolant leakage into the crankcase of an internal combustion engine, thus predicting engine wear problems. Several options for the determination of glycols exist, including colorimetric tests which are easy to perform, subjective to interpretation and not particularly sensitive, fast or cost effective. Gas chromatography can be used for analysis but the ethylene glycol poses problems in the detection and quantification due to its low molecular weight, low volatility, and high polarity. Chromatographic peak shapes are often difficult to control and carryover can be a problem. Injecting in-service engine oil directly into a gas chromatograph for the determination of ethylene glycol introduces high molecular weight oil and non-volatile components into the injector and the column. This makes chromatography slow, reduces column lifetime and severely limits throughput, since high boiling components from the oil matrix must elute before the next injection. This method involves a very simple in situ derivitization technique that allows the glycols to be made more volatile and less polar. Headspace extraction is used to isolate the glycols from the complex sample matrix and injection into a gas chromatograph for rapid separation and quantification without the oil matrix.
This method is needed to more easily determine if in-service lubricants contain coolant contamination. This method offers a more rapid and reliable technique for the determination of glycol in lubricants.
The title and scope are in draft form and are under development within this ASTM Committee.Back to Top
Frank Di Sanzo