Chromatography Forum

Hi,

I am new to gas chromatography. I am setting up some dentrification potential assays and need to measure nitrogen levels. I am having trouble setting up my standards. I can not get my 100ul sample to be able to detect nitrogen peaks. I need to set the best sensitivity. I am using a Varian 3700 model chromatograph with ECD. It has an option for range of ECD 1 or 10 which is a multiplication of whatever I set the attenuator to. The levels on the attenuator are 1-1024 so possible levels range from 1-10240, what does this do to my signal??? I hope someone can help, thanks in advance.

MB

mburto2,

Are you trying to measure nitrogen on the ECD or are you trying to measure nitro compounds on the ECD? If the former, I would be surprised an ECD would work. Much better to use a TCD or HID if you are trying to measure nitrogen. If the latter, then it has a good chance of working especially if multiple nitro groups on your desired component.

While I dearly love the 3700, this is going to be a real challenge due to the age of the chassis you are using. Having said that, range 10 is more sensitive than range 1. Attenuation changes the output (the signal on a 3700) by 1/2^n where n is the attenuation setting. Unless you are clipping the peaks you are interested in, it is generally left at 1.

The more information you provide, the more help you can get.

Best regards,

AICMM