methyl ethanolamine quantification questions

I am trying to quantify methyl ethanolamine (MEA) by GC but had a hard time. A while ago I was able to quantify it with external standard method from 100 to 1000 ppm in Methanol using a Rxi-17Sil MS column. However, in recent months, we had a hard time seeing MEA by the same column, the peak was either super tailing or we could barely see anything lower than a few hundred ppm. I also tried DBwax (no peaks at all) and DB1701 column (similar to what it was observed above). What would you suggest doing? Using a different column, a column with thicker coating, etc.? Thank you. 

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