How to do Nitrogen blow down

[sami6]

Hi all,
I am new to chemistry but a botanist.
I have an issue of concentration with my plant extract samples. I need to concentrate them since they are more diluted. I have found that Nitrogen blow down can help me. Can somebody please tell me the steps of how to do the process practically. This is totally new to me.

[Consumer Products Guy]

Set up a supply of nitrogen (such as: from a nitrogen cylinder) with a small step-down regulator and route the slow nitrogen flow through a tube to a disposable glass pipet directed at your extract. Some extracts can be warmed on a steam bath while doing this.

Obviously, using nitrogen for this instead of dry air gets oxygen out of the picture.

[Steve Reimer]

In general, the nitrogen flow show dimple the surface but not splash. The rate you can reduce the volume will depend on the boiling point of the solvent and how volatile the components are looking for are.
Be careful of the tubing if you are going to have any GC analysis done on the extracts. Phthalates from many kinds of tubing will transfer into the extract. If you are unsure, test before committing valuble samples to the system.

[sami6]

Many thanks to both of you. I did a test trial using a glass pipette as you have mentioned.
Do I have to insert the tip of the pipette into the sample or have to keep it above the top level of the sample? In my trial I inserted the tip, but I feel it is not the way.
I am going to analyse the samples on HPLC.

[Don Shelly]

Many thanks to both of you. I did a test trial using a glass pipette as you have mentioned.
Do I have to insert the tip of the pipette into the sample or have to keep it above the top level of the sample? In my trial I inserted the tip, but I feel it is not the way.
I am going to analyse the samples on HPLC.

Above the sample. To quote Steve, "In general, the nitrogen flow [should] show [a] dimple [on] the surface but not splash".

[Consumer Products Guy]

Do I have to insert the tip of the pipette into the sample or have to keep it above the top level of the sample?

Wow, thought my response in the earlier post was clear, stating "directed at your extract":

...route the slow nitrogen flow through a tube to a disposable glass pipet directed at your extract...

[oscarBAL]

Hi Sami; look in youtube; this could give you some adieas
http://www.youtube.com/watch?v=k3AC-9CcNN4
http://www.youtube.com/watch?v=bOpHvch0vQg

[MSCHemist]

I have a crude setup with nitrogen, a regulator, and 1/4" Cu tubing branched into 8 branches each connected to some tygon tubing and ending with a pasteur pippette. I have a hot plate with a metal rack for 22ml headspace vials. I set it to heat at 70 deg. The capsaicinoid aren't going anywhere.



I mainly use it for scoville heat units. I use the ASTA method which is extract with ethanol, sent through c18 cart, then I blow down to dryness and redissolve in 1ml MeCl2 with hexacosane ITSD. Then GC-FID.