[w4rlock]

Hi, we have a stock problem with glass capillary tubes for TLC. Any Europeans here that can suggest a manufacturer/supplier?

[discodermolide]

Hi, we have a stock problem with glass capillary tubes for TLC. Any Europeans here that can suggest a manufacturer/supplier?

Why not use Pasteur pipettes warm the end with a heat gun and draw it out when soft, they make great capillaries.

[Dan]

Yeah, either pull your own from Pasteur pipettes or use a blunted needle.

I use a blunted 21G needle, you can easily clean and re-use it and it wont snap if you drop it etc. Only ever have to replace them every year or so.

[nox]

dumb question -- how do you blunt the needle, file it down or something?

[w4rlock]

yea, I'm asking because my professor is considering making us make them out of pasteur pipettes and I was hoping that we wouldn't have to resort to that!

The needle idea is great. But still if anybody knows where we can purchase some from please let me know.

Thanks

[Dan]

dumb question -- how do you blunt the needle, file it down or something?

Remove the sharp end with wire cutters. This will also flattens and closes the end of the needle, but you can open it again by applying a bit of pressure with pliers.

I started doing this a few years ago when I got fed up with people stealing my glass capillaries (pulled from Pasteur pipettes). I don't see any advantage of glass over steel for TLC spotters.

yea, I'm asking because my professor is considering making us make them out of pasteur pipettes and I was hoping that we wouldn't have to resort to that!

Making your own glass spotters is a bit time consuming, needles you blunt it once and is good until it blocks. If you look after it you won't need to make another steel spotter for a couple of years. If your professor's concern is money, the needle option is the way to go.

You can buy glass capillary tubes from most lab suppliers. SLS for example:

http://www.scientificlabs.co.uk/product/HAE3150

[OC pro]

I have been using hundreds of Ringcaps(R) from VWR. Give good spots on TLC.

[fledarmus]

Most needles are very brittle steel - the procedure I was taught for cutting them is the same as cutting glass tubing. Scribe one side with a fine file, then snap the end off with a pair of pliers. If you have the appropriate size needle-cleaning wire in place when you do this, the opening is even rounder.

[djt]

I don't see any advantage of glass over steel for TLC spotters.

I'm intrigued by this. Granted a 21G needle is very small, but no where near as small as a spotter drawn from a capillary tube or pipette. Do you not overload your TLC plate or get a large spot resulting in poorly defined separation? Or do you use a more dilute solution than you would for ca. capillary drawn spotters?

I might give this a go when I do a TLC next.

Alrdich are showing stock for Stuart mpt. tubes

http://www.sigmaaldrich.com/catalog/product/aldrich/z673250?lang=en&region=GB

djt

[BobfromNC]

I found some very fine TLC spotters many years ago, and they are excellent.   The problem was that they had to be made in large orders, so we had to buy a bunch.   They are about 1 mm dia and 100 mm long, and come 1000 to a tube, they cost us about $40 per tube.   If anyone is interested in getting some, send me an email at craigslistinnc at gmail-dot-com and et me know where you are.   These are very fine, so they are great if you want to run many spots per plate (I usually do 6 spots per 2.5 cm plate and 12-16 on a 5cm plate).   Chemglass and a few other companies sell spotters, but find that they make far too large a spot for good TLC of close spots.  

Bob

[Dan]

I'm intrigued by this. Granted a 21G needle is very small, but no where near as small as a spotter drawn from a capillary tube or pipette. Do you not overload your TLC plate or get a large spot resulting in poorly defined separation? Or do you use a more dilute solution than you would for ca. capillary drawn spotters?

Well, the spotters I used to pull from Pasteurs were not much thinner than a 21G needle, so I learned to work with that sort of thickness. My TLCs look fine, spots are usually ~2 mm in diameter and not overloaded.

[w4rlock]

Thanks! I will try VWR and SLS and see from there. I will also experiment with using a needle - I can't see any downside to this and it's the cheapest option. 

[Doc Oc]

I agree that pulling them from Pasteurs is the easiest and most economical way, though I like the idea of using a 21 gauge needle.  When I was a grad student we bought a brand called Drummond, don't remember where we got them from though.  They're nice in that they're uniform in length and inner diameter, but I wouldn't say so superior to your own pulled spotters that I'd recommend them above that.

[fledarmus]

I wish I could still pull caps from pasteurs. Or do any other glasswork for that matter. I haven't had access to a flame in the lab for close to 15 years.

[djt]

H & S?

I wish I could still pull caps from pasteurs. Or do any other glasswork for that matter. I haven't had access to a flame in the lab for close to 15 years.

We only have one bunsen left and I have to hide that when there's an inspection. Also very useful for distillations. Could you not get a blowtorch? That's what a few of the newer labs in my place use as they no longer have a gas supply.