Sciencemadness Discussion Board - Titration practice with OTC Drugs

Titration practice with OTC Drugs

Little_Ghost_again - 16-10-2014 at 14:20

Hi
In need of skill polishing and getting bored with acid base titration, I am interested in seeing how accurate I can get using the scales I currently have (see other thread).
My reasoning is if I pick a OTC drug it will obviously have a stated does per tablet.
This should be an excellent way in making up a solution to titrate it and see how close I can get to the actual stated does in the drug.
Where this falls down is in picking one and a reagent I can buy and make up into a solution to titrate it.
Any suggestions? apart from antacids

.
I am after the drug and the reagent needed to titrate it with. I just thought would be a great way to see how close I can get with the equipment I have on hand

DraconicAcid - 16-10-2014 at 14:25

You can titrate aspirin with a strong base; you just have to add enough alcohol to the solution that it dissolves (don't heat it, or it will hydrolyze).

macckone - 16-10-2014 at 14:33

Basically anything that is listed as a hydrochloride or sulfate salt.
The european pharmacopia has plenty of tests you can run on
various drugs.

DraconicAcid - 16-10-2014 at 16:04

You can buy campden tablets (potassium hydrogen sulphite) at a brewing store.

Little_Ghost_again - 16-10-2014 at 16:09

Quote: Originally posted by macckone

Basically anything that is listed as a hydrochloride or sulfate salt.
The european pharmacopia has plenty of tests you can run on
various drugs.

I tried getting a copy of that from the library here, but the links were dead.
Any idea how best to get hold of it?

Texium - 16-10-2014 at 16:16

Quote: Originally posted by DraconicAcid

You can buy campden tablets (potassium hydrogen sulphite) at a brewing store.

According to Wikipedia, campden tablets are actually sodium metabisulfite. (or potassium, but it seems like either way it's the metabisulfite)

DraconicAcid - 16-10-2014 at 18:46

Quote: Originally posted by zts16

Quote: Originally posted by DraconicAcid

You can buy campden tablets (potassium hydrogen sulphite) at a brewing store.

According to Wikipedia, campden tablets are actually sodium metabisulfite. (or potassium, but it seems like either way it's the metabisulfite)

So it is. I've gotten into the very bad habit of ignoring "meta"s unless it's on a disubstituted aromatic ring.

DJF90 - 16-10-2014 at 23:05

You could titrate ibuprofen with strong base/phenolphthalein.

blogfast25 - 17-10-2014 at 04:58

Anti-acid tablets often contain aluminium hydroxide. It can be back titrated with EDTA. I have an established procedure for it.

Amos - 17-10-2014 at 05:12

Back titration is a useful technique to consider indeed. If you haven't already, just give it a search on google and read up on it some.

Little_Ghost_again - 17-10-2014 at 06:14

Thanks chaps.
Blogfast I would be interested, I have another type of back titration I need to do as well, so any practice in that is good.

macckone - 17-10-2014 at 10:49

Quote: Originally posted by Little_Ghost_again

Quote: Originally posted by macckone

Basically anything that is listed as a hydrochloride or sulfate salt.
The european pharmacopia has plenty of tests you can run on
various drugs.

I tried getting a copy of that from the library here, but the links were dead.
Any idea how best to get hold of it?

http://bookzz.org/md5/BD4DB40362F41E0B577C33B08D614F9A

blogfast25 - 17-10-2014 at 11:23

Quote: Originally posted by Little_Ghost_again

Thanks chaps.
Blogfast I would be interested, I have another type of back titration I need to do as well, so any practice in that is good.

If I remember not to forget I'll U2U a scan of it.

In essence the Al(OH)3 is extracted from an accurately weighed quantity of tablet by HCl digestion. After buffering an known amount of standard Na2EDTA is added and the mixture heated (Al EDTA complexes only form slowly) for about 5 minutes. After cooling the excess Na2EDTA is back titrated with standard zinc sulphate. Off the top of my head...

[Edited on 17-10-2014 by blogfast25]

aga - 17-10-2014 at 12:36

I'd like a scan of that too please.

blogfast25 - 17-10-2014 at 12:52

Quote: Originally posted by aga

I'd like a scan of that too please.

Always the same, eh? What Little_Ghosty wants, Little_aga wants too. What did I say about playing with your own toys?

No attachments in U2U so I've attached it here. It should be perfectly possible to use Eriochrome T indicator instead of spectrophotometric detection of end point.

The whole booklet called 'Practical Titration' can be obtained from 'Metrohm' for FREE. Very oldy worldy they actually sent me a clean hard copy by snail mail! 163 pages.

[Edited on 17-10-2014 by blogfast25]

macckone - 18-10-2014 at 07:21

Lots of good stuff from metrohm
http://www.metrohm.com/com/Applications/literature/monograph...

aga - 18-10-2014 at 07:26

fabulous !

thanks very much for the info.

Little_Ghost_again - 18-10-2014 at 09:22

Yes thanks alot, I also found 2009 british pharmacopia as torrent, I will stick the link in references.
Thanks for the info. On the downside the scales I was watching on ebay have gone past my price bracket!! But they do pop up now and then, I should have gone for the old wooden case balance ones as no one bid and they could have been had for £40.