Chromatography Forum

I am trying to load a sample(it can be water an isolated cell) into a capillary of length 550 micro meters, what are the different ways that i can load my sample into the capillary.

It would be really great if someone could help me with this.

Hey,

I assume you want to load the capillary as it is,not while installed in a GC ?

You can use a syringe which is coupled to the capillary with an appropriate connector and than introduce your sample into the column.

Even a GC syringe with a needle (OD smaller than 0.53 mm of course) can be used to introduce your sample ( on column syringe)


Or you can use vacuum to suck you sample into the column.

hope that helps ?

thanks a lot for your reply. yes you are right, i am not installing the GC, becoz in my lab we dont have the chromatogrpahy equipment. I am not a chemist student, i am biomedical engineer who is working on imaging samples. I just have another question: is this a simple method by which i can load my sample as per my requirements in the lab.

Is the capillary 550µm in length or in diameter?
As Philippe pointed out you can use a simple syringe with appropriate fitting to load the capillary. Pressure or a vacuum is also very easy. I used to use a very cheap and small aquarium pump to load capillaries ranging from 50 to 500µm in diameter. Some vials, appropriate rubber septa and needles is all you need.

I am sorry, 550µm is the diameter, okay thank you, will try this if it works

By far the easiest way is to simply dip the end of the capillary into the sample - the liquid will rise into it by capillary action. You can control how fast and how far it rises by adjusting the angle of the capillary, or by putting your finger over the open.

Filling capillaries like this is common practice in blood work and you can get calibrated capillaries of various volumes and diameters, with dispenser bulbs and other accessories.

Peter

Thanks Peter, this did work for a capillary which is 1mm but for my capillary which 570micro meter, it didnt work this way. I am trying the other ways tooo.

There are two possible reasons why this works with a 1 mm capillary, and not with a 570 micron capillary; either you have particles in the sample that are bigger than 570 micron so they block the tube, or you have a hydrophobic surface treatment on the inside of the capillary that stops the water from wetting it. What is the capillary made of ?

Peter

hey Peter
yeah you are right, might be there were some particles that blocked the flow, my capillary is a fused silica capillary coated with a thin polymide layer. Is it possible by connecting a tube(OD should be greater than 570micro meter) to the capillary and then a syringe to the same tube, so that with the help of a syringe i can load sample to the capillary.

Thank you

Is the polyimide on the outside or the inside of the capillary ? If it is on the outside it will not affect the capillary rise into the tube. Is there a coating or hydrophobic layer on the inside of the tube ?

You can certainly fill the tube by attaching it to a syringe, but you will need to use a low volume syringe and work very carefully or you will suck the sample right through the tube into the syringe. This will not work if the sample has particles in it that block the tube.

Peter