I have A CE2500 Elemental Analyzer which feeds a Delta+ MS and I am having problems with the EA unit. After setting the EA up for doing suflur, i found that the peak shape for SO2 was good for the first couple of samples but degraded rapidly after that in the form of a large tail or nearly double peak (10-15 samples later). I was not able to detect any leaks using a GO-MAC leak detector, however, performing the leak test suggested by CE yields a 40-50 kPa pressure drop over 5 mins, which is somewhere between where the carrier gas enters the sample changer to end of the reactor tube. I am new to EA machines so I am at lost as to what would cause the peak shape to degrade so rapidly. Anybody have any suggestions. -- ======================================= Gregory A. Wandless Chemist US Geological Survey MS954 Reston, VA 20192 Email:[log in to unmask] Phone: (703) 648-6189 =======================================