Chromatography Forum

Has any of you guys done natural gas liquids analysis by GCMS?. Im pretty new to oil and gas .....i was given a natural gas liquid sample in a canister and told to analyze it by GCMS (no one in the lab has done this before and the GCMS is new to the lab and im the first to use it). Well i ran it and im getting nothing....no peaks!! I am reading about Natural gas liquid and seems to be pretty light hydrocarbons butane, propanes etc. Im thinking when i open this sample canister and pure the liquid into a beaker and then transfer into a normal gc vial that the contents are just floating away!! or am i doing something wrong! and if they are floating away then what is the liquid that left!....I would grealty appreciate some help here

LPG neds to be kept pressurised or it will evaporate quickly
You need a method of turning your LPG into a gas in a controlled manner so it can be injected into your GC/MS
See this application note for one method
http://www.gassite.com/shop_image/docum ... 29252c.pdf

seamoro,

You will notice two things that are critical about the posted application note. 1) The sample comes to you in a Whitey cylinder so that the contents never have to de-pressurize and 2) the sample valve is an internal rotor and blocked by a valve on the other side so you can load the valve under pressure before injection. Gas phase conversion can happen at the inlet with, typically, a split injection. If you are really talking natural gas liquids, the transfer to the inlet could be a bit sticky depending on how heavy the hydrocarbons are. Theoretically, they should be pretty light, but not always so you might have some discrimination.

Also keep in mind that C1 and C2 are both low mass components so you will have to force your MS below 20-30 AMU which means you will now be below O2, N2, and water in your mass spec so your baseline will be very noisy. Usually this method is done on an FID to be immune to this issue.

Best regards,

AICMM

What is your objective for running GC-MS on NGL?

As discussed above, your only options are using a liquid sampling valve or flashing the NGL into a tedlar bag to inject the sample.