AOCS Cd 11b-91 Mono- and Diglycerides

[II5tickmanII]

Hello, I am hoping the community and experts here may be able to help with a few quesitons i have?

Question:
Does anybody routinely use this method AOCS Cd 11b-91, if so what column would you recommend and basic GC conditions?

Background:
Looking to change routine analysis to this method. Currently i am trialling the method using an Rxi 5Sil MS 15m x 0.25mm x 0.25um on a HP5890 series II. Same GC set up as recommended in the AOCS method, 1ul injection with a 50:1 split and 2.0ml/min flow.

Problems:
1) The needle plunger keeps sticking, even when performing 6 pre and 6 post injection flushes (3 of Iso-Octane and 3 of Hexane)
2) The baseline tends to rise dramatically at approx 300C and again at approx 320C (oven program as AOCS method is ramp at 10Cmin from 80C to 340C and hold at 340C for approx 30mins)
3) When injecting a vial cointaining the same conc of n-teradecane ISTD, 1,3-PP Diglyceride, and 1,3-SS Diglyceride Standard the responses (calculated from peak areas) seem low. Approx 0.860 for the DGs

Any help or comments would be appreciated. Thanks.

[KM-USA]

We would do this assay by dissolving the sample in DMF or pyridine, and derivatizing with BSTFA.