Manual headspace method

[seet88]

Hi all,

Just want to ask regarding some manual headspace method. I want to ask if my two compounds of interest in water have different boiling point (110degC and 300degC) in water, how am i going to set the oven temp? Because i try to put lesser volume in headspace vial due to water vapour pressure high, will cause expansion of the vial cap till loosen. I do try heat at 110degC, i able detect 110degC compound, but when not able see 300degC compound; if i heat at 180degC, the water inside become dryness, and found cap is loosen, but able detect 300degC compound, not able see 110degC compound (mayb due to loosen cap). Anyone can give advise on this?

Thanks
Seet

[larkl]

I'd argue that headspace isn't a good option for a compound with a 300 C boiling point in a matrix with a boiling point of 100 C. Some might argue that gas chromatography isn't the best option for something with a 300 C boiling point.

[Peter Apps]

If you insist on using headspcae for a compound that is not suited to it then your only practical option is to put in a small sample (less than 50ul) and evaporate it completely. You will find several posts on this if you search the archives.

Peter