WEF Discussion Forums
Laboratory Management and Technical Issues
Oil and Grease by Soxhlet
Our laboratory tests for hexane extractable material (oil and grease) using a Soxhlet based on APHA 5520 D. Following a recent audit, it was determined that we should be using hexadecane:stearic acid as the control sample instead of Wesson Oil and No 2 fuel oil. Our historical recovery limits were satisfactory. Unfortunately, the recovery has been unsatisfactory ever since we changed the control sample. Does any one within this group achieve satisfactory recovery of hexane extractable material using a Soxtec or Soxhlet? I would be keen to know your method details.
I received a private email message on this subject and received an email back stating that the return address (firstname.lastname@example.org) was invalid. The question was:
Subject: Oil and Grease
Did you solve your recovery issues with the new standard? I'm curious because we are having similar issues here in our lab.
My answer was:
Yes and no. We are not able to quantitatively recover hexane extractable material when using hexadecane as the laboratory control sample. The extraction process using a soxhlet or automated soxhlet device and the drying oven per APHA 5520 D volatilizes the hexadecane. However, we are fortunate in that our regulator has identified USEPA 5520 D as an approved procedure and we do quantitatively recover hexane extractable material with mineral and vegetable oil as the LCS.
Charlie Pierce | Project Director - Chemical
Monitoring Programs / Monitoring Services - Analytical | Sydney Water
51 Hermitage Rd West Ryde NSW 2114
PO Box 73 West Ryde NSW 2114
T 02 9800 6024
Thank you. I wasn't a member before and so I couldn't post to the forum.
Using the method 5520B and the same standard i face the same problem as the recoveries are in the 80% region.