Has anyone come across gross contaminants when using acetyl chloride for transmethylation of lipids? We analyse our samples on gc/ms after methylation. We distil the acetyl chloride before use, but with the current batch we have had some strange compounds eluting very early on with m/z values ranging from 521,535,549,563,577,595 ( also m-15 ions) of the above values. The problem is that once we have run a sample which has been contaminated with these artifacts, the column resolution is destroyed, and the baseline becomes very noisy and large troughs and crests. We have used acetyl chloride for years, with no such problems. I suspect that, perhaps we collected some contaminants as well while distilling. My question is: does anyone know what the contaminants might be? Has anyone else experienced a similar problem? Would be really grateful for any responses, because this is driving me mad!!
Thanks a lot for wading through all this