I was wondering if anyone else has observed trouble with separation between tyrosine and lysine on newly purchased columns? Our aging column in one of our Trace GCs is starting to show its age, but we've tried several new columns and consistently get bad separation between tyr and lys (all other AAs look fine). We have historically used SGE BPx5 (60m x 0.32mm x 1.0um) columns with success, but we've tried multiple new BPx5 columns as well as an Agilent DB5 (also 60m x 0.32mm x 1.0 um) with the same results.
Has anyone else had this trouble? The old columns were purchased in 2011/2012, and all the troublesome columns have been purchased since late 2015.
Isotope Biogeochemistry Laboratory
University of Hawai'i at M?noa
(808) 956 5362