Pay, pay, pay.
Expect the pay to be very low in realation to others in the same exact field. This is the trade off for getting good mass spectroscopy experience. Also, expect very heavy work loads and long days. The toxicology department seems to have trouble keeping people here. This of course come back to the pay issue. This is not even limited to mass spectrometrist, even extraction and screening departments get paid well below average. The pay and the heavy work loads are the biggest issue that keep this company for doing well.