some alkane peaks when doing conditioning

[zimanli]

Greetings,
We would like to install a guard column. When I did conditioning, I got a lot of peaks and the library suggests alkane peaks. Is that bleeding or from my hand cream (did not wear gloves when installed)?

we need to inject some air along the sample. Is 200 uL air harmful to the column?

thanks a lot!

[Peter Apps]

Hi Ziman

Hydrocarbons might come from petroleum jelly (Vaseline etc) but if you managed to get this from your hands into the system you need to review your technique.

As long as the column is cool (say below 80 C) injecting a small plug of air should not do it much harm. If it is hot you will see problems sooner or later.

Peter

[zimanli]

Not only water but also oxygen do very bad to my capilary column, right? My column is HP-5ms. Are there any column that can not be attacked by O2 and H2O?

[GOM]

As Peter said, if your column is cool it should not harm it. I would suggest less than 50°C for wax phases. Don't forget, air is 80% nitrogen.

What is of more concern is that you said the library identifies the peaks as alkanes - does that mean you are using GCMS? If so, ensure your filament is off during the elution of the air peak otherwise it will shorten its lifetime.

As for water, most phases are happy with water injections - just keep the volume to 1ul or less (depending on your liner) to avoid over-expansion problems in your liner.

Ralph