Sample pre-treatment accounts for 60% of the sample analysis process and directly affects the test results. In ASTM D7303, Standard Test Method for Determination of Metals in Lubricating Greases by Inductively Coupled Plasma Atomic Emission Spectrometry, two methods for sample pre-treatment of lubricating greases, the ashing method and microwave digestion method, are explained.

The ashing method, which involves the thermal reaction of samples and concentrated sulfuric acid in a platinum crucible, is usually time-consuming and dangerous, but the ashing method is more commonly used because of its relatively low input cost.

The other microwave digestion method puts the sample and concentrated nitric acid or other appropriate inorganic acid into a PTFE digestion vessel and react in a microwave digestion apparatus. The reaction time is short, and multiple samples can be taken at one time, but the microwave digestion equipment is expensive to purchase.

With a growing awareness of safety and efficiency, microwave digestion have become the laboratory of choice. Similarly, for the sake of efficient test results and safety of employees, Runningland has replaced the more commonly used ashing method with microwave digestion method this year and currently in operational use. This new additional equipment can complete test projects much more efficiently.