Sciencemadness Discussion Board - TLC solvent system for Tea and Coffee?

TLC solvent system for Tea and Coffee?

NEMO-Chemistry - 28-10-2017 at 17:36

If I get time Sunday I want to extract caffeine from tea and coffee. Before I extract this I would like to do a TLC on both Tea and coffee, I am interested particularly in the tannin's etc in tea.

But figured I might as well do coffee as well before extraction and then obviously do a TLC on both afterwards.

Using glass backed cellulose TLC plates, what solvents would be best to develop the TLC plates? The plates I am using have a fluorescent dye in them, so I can visualize with UV lamp afterwards.

EDIT
Sorry i forgot to add i dont have Ethyl acetate or Hexane at the moment, hence why i am hoping for another option

edit 2
Lets make it easier! Is heptane the stuff in lighter fluid sold as liquid lighter fuel? If so then Chloroform and heptane?
[Edited on 29-10-2017 by NEMO-Chemistry]

[Edited on 29-10-2017 by NEMO-Chemistry]

LearnedAmateur - 29-10-2017 at 06:02

Lighter fluid/light naphtha is a mix of pentane and hexane but it could also contain some heptane and octane depending on the brand. Your best bet would be to check the boiling points - literature states that the light naphtha fraction boils between 30 and 90 degrees Celsius, whereas heavy naphtha from 90 to 200. Shouldn't be too difficult to distill off the pentane though if you want somewhat pure hexane.

This publication states a butanol:HCl:water mixture (100:11:28 by volume) was used to develop the cellulose plates for 4 hours in order to analyse both tea and coffee. Maybe you can substitute the butanol for isopropanol or ethanol if you don't have any?

https://books.google.co.uk/books?id=Rgs_rVOceZwC&pg=PA20...

NEMO-Chemistry - 29-10-2017 at 06:23

Thats great thank you. I have IPA (ethanol is like gold around here lol), not sure why I thought lighter fluid was heptane. I need to look into that!

But IPA,HCl and water is a nice easy way to go. Solvents are getting more expensive, my normal source used to sell 'gunwash' which was a spray gun cleaner, this used to be almost 99% toluene and was real cheap. Now its just a complete mix of whatever solvents they got left by the look of it, around 7 different solvents in small amounts.

But the good news is they have now swapped a solvent based brake cleaner for 95% Ethyl Acetate and its cheap, and the industrial methylated spirits is >95% Ethanol with a little methanol and no dye. This is also cheapish. They are not selling it until after Christmas though. But solves the headache of getting Ethanol which I normally make.

I appreciate the information. Although I am after the Caffeine, i am interested in what tea contains.

Managed to track down a copy of the book you linked too, so thx again.

[Edited on 29-10-2017 by NEMO-Chemistry]

Metacelsus - 29-10-2017 at 06:28

Tannins, caffeine, etc. are quite polar. Chloroform/methanol might be good as a solvent system. If you want to analyze alkaloids adding 1% of concentrated ammonia solution (if you have it, triethylamine is better) will help basic compounds elute.

As a start, I would suggest (by volume) 90 parts chloroform : 9 parts methanol : 1 part 30% ammonia solution.

[Edited on 10-29-2017 by Metacelsus]

LearnedAmateur - 29-10-2017 at 08:02

Pure ethanol is quite hard to get if not ordering small quantities online, it tends to be 95% with water. I usually use surgical spirit as my source of ethanol but I'll probably buy some of the purer stuff when I need some more and try to dry it to 100%. Isopropanol is the best way to go if you need a pure alcoholic solvent IMO, since it's very cheap and a lot more common than higher chain alcohols. I haven't had any problems ordering pure toluene online if you have trouble finding it in store, even up to 25 litres which is around £50.

If you're looking into extracting caffeine then it might be worth your while to look into column chromatography? Small (<200mL) columns aren't much more expensive than your average piece of glassware and it's quite easy to collect a range of compounds on the gram scale with just a few batches or possibly one with an addition funnel. The material used for the stationary phase tends to be quite cheap too, silica gel or alumina, cellulose powder too if you come across it but this is probably the more expensive option.

SWIM - 29-10-2017 at 08:18

Quote: Originally posted by LearnedAmateur

Lighter fluid/light naphtha is a mix of pentane and hexane but it could also contain some heptane and octane depending on the brand. Your best bet would be to check the boiling points - literature states that the light naphtha fraction boils between 30 and 90 degrees Celsius, whereas heavy naphtha from 90 to 200. Shouldn't be too difficult to distill off the pentane though if you want somewhat pure hexane.

This publication states a butanol:HCl:water mixture (100:11:28 by volume) was used to develop the cellulose plates for 4 hours in order to analyse both tea and coffee. Maybe you can substitute the butanol for isopropanol or ethanol if you don't have any?

https://books.google.co.uk/books?id=Rgs_rVOceZwC&pg=PA20...

HOLY CRAP!
I'd always assumed lighter fluid was some sort of aromatic based on the smell (guess my nose isn't as reliable as I thought).

Here I'd been wondering what I was going to distill to get some light petroleum ether not knowing what a simple easy source was available.

Sounds like a I'll be able to get a nice low boiling, (and a higher boiling) ligroin out of that with virtually no waste by a careful fractionation!

Now I can save my dwindling hexane stock for when I really need straight hexane.

NEMO-Chemistry - 29-10-2017 at 10:46

Swim you in UK? I just found a great source for naptha and other solvents at a good price.

LA I will pm you.

SWIM - 29-10-2017 at 16:10

Quote: Originally posted by NEMO-Chemistry

Swim you in UK? I just found a great source for naptha and other solvents at a good price.

LA I will pm you.

Unfortunately, I'm about 7,000 miles away, but thanks for the offer.

I like the lighter fluid Idea because I can get that any day of the week so I don't have to stock up as much. I try to limit my solvent stockpile because
I currently keep it in the garage.

I really ought to get one of those plastic storage cabinets, put some vents in it, and put it in the back yard. It gets up in the high 30s here sometimes and stuff like methylene chloride, pentane and hexane have a way of getting loose when they're that warm.

Probably ought to bite the bullet and get some better storage bottles too some day. Boston bottles are okay, but my one Schott bottle really seems to hold the vapors in.

Corrosive Joeseph - 29-10-2017 at 16:37

Lighter fluid definitely has not any pentane or hexane in it

Every MSDS sheet I have ever seen states it is a mixture of petroleum distillates with either a boiling range of 100-125C or
100-150C

/CJ

NEMO-Chemistry - 29-10-2017 at 17:55

In the UK the brand you want is swan lighter fluid, no idea if its naptha or what now?? but will check tomorrow, its definitely a single solvent though and not pet spirit. I checked ages ago for another thread and cant remember what it is!! But it turned out to be good stuff.

The reason its pure is because its for zipo lighters, in the EU you cant go adding cancer agents to lighters, or you might give people that smoke, cancer......... Yeah I know I know, but rules is rules

[Edited on 30-10-2017 by NEMO-Chemistry]

Corrosive Joeseph - 30-10-2017 at 17:54

@ NEMO - I must add that this is for every brand I looked at in the UK.

I found an MSDS for Zippo 'Blend C' (whatever that is) that states an IBP (initial boiling point) of 32degrees but that just didn't sound right. The data sheet seemed American from what I can remember.

The Swan brand sounds interesting but I could get no information on it. I have been playing with the idea of distilling a few of these just for shits and giggles.

Could you please PM your source of naphtha and other solvents. Finding new sources in a dwindling sea is always good.

/CJ

SWIM - 30-10-2017 at 18:33

Quote: Originally posted by Corrosive Joeseph

Lighter fluid definitely has not any pentane or hexane in it

Every MSDS sheet I have ever seen states it is a mixture of petroleum distillates with either a boiling range of 100-125C or
100-150C

/CJ

Glad I'd been lazy about buying some. The msds sheets on American products I checked were BPs starting at 90C.

However My nose is vindicated! I found an MSDS for Zippo fluid from 1994 (my brand and the era when I used to use it to light cigars).

Contents included xylene, ethyl benzene, toluene and benzene

.

I'm willing to bet THAT has been reformulated!

Sure had a great smell though. Sweet and rich and it actually made the cigar taste better.

Ah yes, memories of sucking those sweet, sweet benzene vapors deep into my lungs. Anybody got a cup of bone-marrow I can borrow? I may need it sometime soon.

EDIT: mis-read the document, no Benzene, just naptha, toluene, xylene, ethylbenzene. Hell that's practically health food compared to benzene.

[Edited on 31-10-2017 by SWIM]

Corrosive Joeseph - 30-10-2017 at 18:39

Quote: Originally posted by SWIM

The msds sheets on American products I checked were BPs starting at 90C.

That sounds more like it......... Don't worry about the bone marrow, we have all been breathing petrol fumes for years

/CJ

NEMO-Chemistry - 30-10-2017 at 20:05

I cant find my tin!! I mentioned it in a aga thread somewhere, you might be right.But Let me go check, i will grab a tin and have a look, i cant remember for the life of me what aga was looking for, but i remember finding it pure in a tin of the liquid lighter fluid.

I just cant remember what the hell he was looking for now.

.
I also remember the boiling point is fairly low, below 90C for sure. I had two tins, one was swan one was white. They still sell the same brands in the shop in town, the bonus being i clearly remember the tin stating it was double purified and gave the ingredient.

I dont have the best memory, but i did file the info under 'must remember that for the future'. Although not sure even if I am right, if lighter fluid is the cheapest way to do it!

I did have a cheap source for hexane, but they seem to have gone!

NEMO-Chemistry - 30-10-2017 at 20:09

I will pm you my updated list of solvent sources, there are a couple of good ones currently in the UK. I did some digging and one company sells pretty pure solvents under strange names like 'brake cleaner', and gun wash 32 (Xylene). All pretty cheap.

Let me get back on the laptop later so I can grab my list for you. Most are cheaper than APC although one company is half the price but a subsidiary of them!! Bio diesel companies were good for a while, but these seem to drying up in what they supply.