DJ Patil, Many things can cause carbon peak to be miss shaped. You can have the drop time incorrect and not getting good combustion, you may have restricted 2 mm tubing causing excessive back pressure, the GC column may also have restriction. I am assuming that the system is leak tight because a leak can cause this as well, the EA should be leak checked isolated from your MS. Your consumables may be a problem but I do not know where you are. If I have consumable problems I go to the distributors of the instruments, if you let me know where you are from I can direct you to your authorized Thermo Distributor. Mike Elefante Elf Analytical Services Inc. USA 732-922-8400