Internal Standard Fluctuation EPA 8260
Posted: Wed Jul 28, 2010 3:36 am
HELLO~
Anyone out there offer some suggestions as to why internal standard, most notably ion 96 fluorobenzene decreased in area counts from intial cal. The area of 96 was very stable over months, then dropped 40 %, HOWEVER, once a "high" concentation sample is analyzed, the area bounces back, then after 2 or 3 sample comes back down. I have changed analytical trap, did some tubing changes with the concentrator, Velocity, and still no solution. The other compounds are also depressed in area counts, but ion 96 is the most noticeable. Seems to point to an active site that is passivated with a high concentration sample? Where would this active site be?? Please help with any suggestion. Oh, the transfer line was also changed with no help.
Anyone out there offer some suggestions as to why internal standard, most notably ion 96 fluorobenzene decreased in area counts from intial cal. The area of 96 was very stable over months, then dropped 40 %, HOWEVER, once a "high" concentation sample is analyzed, the area bounces back, then after 2 or 3 sample comes back down. I have changed analytical trap, did some tubing changes with the concentrator, Velocity, and still no solution. The other compounds are also depressed in area counts, but ion 96 is the most noticeable. Seems to point to an active site that is passivated with a high concentration sample? Where would this active site be?? Please help with any suggestion. Oh, the transfer line was also changed with no help.