ASTM E1868: Loss-on-Drying by Thermogravimetry (TGA) for the determination of volatile organic compounds (VOCs)

ASTM E1868 Loss on Drying by Thermogravimetry

Lubricants may contain light ends and contaminants including water, alcohols and light hydrocarbons. If the light ends evaporate during use, it may shorten lubricant life and change viscosity. This test determines evaporative loss of lubricants at elevated temperatures.

The sample is weighed and placed in the thermogravimetric analyzer (microbalance in a heat-controlled oven with a constant gas purge). It is heated to the test temperature for the test time (Procedure A) or until a predetermined mass loss is observed (procedure B). Reported is the percent loss-on-drying (Procedure A) or time (Procedure B). Please specify temperature.

NOTE: loss-on-drying vs. water content – This method determines the total level of water plus other light ends in a sample. Because water in a lubricant may decrease its useful life, water content alone is often of interest. Please see our discussion under ASTM D4377 for water content methods. For evaporative loss of all light ends, choose either a hot oil bath method (ASTM D972, FTM 350) or a TGA method (ASTM E1868 or ASTM E1131). TGA methods are typically run at higher temperatures and for shorter times than hot oil bath methods. When selecting between ASTM E1868 or ASTM E1131 (TGA methods), consider the specification requirement – either method allows you to select the temperature and time of the test.

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