How to make it 1mL?

[carl.nott]

Not sure what exactly you're doing, but I figured I'd mention that EPA-3510 (and maybe some others) specify that you do not blow down below 1mL during extraction.

In my experience (in environmental labs) folks use graduated concentrator tubes and an extraction surrogate.

[jwhite]

At my laboratory we have glass 1mL pipettes that we use to bring samples up to a 1mL final volume

[Jumpshooter]

Kaderna-Danish concentrator is what we use.

[faris]

evaporate the whole and add 1ml or what ever you want.

[jh1]

You can buy calibrated gratuated glass tubes or just make your own by etching .5 and 1mL fill marks, either way it will be much more accurate than using the fill lines on GC vials.