Chromatography Forum

we are new to our agilent 7000B serious triple quadrapole GCMSMSsystem.i have few doubts on GC methods.we have using splitless injection with 1μl as injection volume.There is term purge inlet flow at 1 min the service engineer set this as 50ml/min and the total flow is near to 55 ml/min.We are using backflush in constant pressure mode.the inlet preasure is set at 27psi during run and 2psi in backflush mode and at PCM preasure set at 3psi during run 40psi in backflush.The method is ok or not Do you get the results that you need ? If you do the method is OK.Our helium cylinder is empting very fastly How long does the cylinder last ? Are you sure that you have no leaks in the gas lines ?.There is any need for purge inlet flow when the system is not runing ie in stand by mode. There is a gas saver setting - you can set it to whatever flow you like
Secondly what is the relation between flow and oven temperature in constant pressure mode As temperature goes up, flow decreases which increases analysis time. Are you able to operate the backflush in constant flow mode, or is it limited to constant pressure ?

Thanks for the reply.Actually there was a leak in the SS tubings thats why the gas is emptying fastly.Actually it was not detect by the instrument during air water cheak.In 7000 MS the air water is comared with M/Z 69 so the ratio will come low.