Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
Author: Subject: Purity Testing
International Hazard

Posts: 1543
Registered: 16-6-2014
Member Is Offline

[*] posted on 21-9-2016 at 08:10
Purity Testing

Can anyone tell me how I would go about testing the purity of a few substances such as KCl, CuSO4 and Ca(NO3)2? I need to find out the % composition of the primary composition and what contaminates may be present. I suspect I would have to send the samples to a lab but I don't know where to look for a company that does this or what the proper terminology for the testing would be. Can anyone help with this?

View user's profile View All Posts By User
Texium (zts16)
Thread Moved
21-9-2016 at 08:11
International Hazard

Posts: 3011
Registered: 8-2-2015
Location: UK ... on extended Holiday in Malaysia
Member Is Offline

[*] posted on 21-9-2016 at 08:50

This is where I have problems too,

The most general tests for purity are melting and boiling points,

If you synthesised the compounds yourself then you should know what 'impurities' to specifically test for.

If putchased then look at a typical reagent grade supply (ACS etc.) to see which contaminants are common.

I do not know if it helps but KCl, CuSO4 and Ca(NO3) each have increasing solubility with temperature so are good candidates for purification by recrystalisation.

That's the limit of my knowledge, hopefully better informed members can help more.

CAUTION : Hobby Chemist, not Professional or even Amateur
View user's profile View All Posts By User
International Hazard

Posts: 1269
Registered: 28-7-2005
Location: Good Olde USA
Member Is Offline

Mood: Integrated

[*] posted on 21-9-2016 at 09:23

I'd look for "contract analytical services" or "enviromental testing."

If I was send this to a lab, I'd ask for metals by ICP (can do all of them simultaneously, but it's cheaper to specify which ones because they frequently charge by element) and anions by ion chromatography.

Some labs may be equipped to do cations via ion chromatography, as well (Na, NH4, K, Mg, Ca, etc. are easy to do); this may be cheaper.

If the materials are completely soluble (and free of organic matter), you can save money by having them avoid digestion prior to analysis.

I'd do % solids (gravimetric) myself.

Then, I can calculate % w/w (dry solids basis) based on the analytical results as % (or ppm) over dry matter. If all is well, it should add up to be something quite close to 100. The difference would be unknown impurities and/or analytical error.


[Edited on 21-9-2016 by Ozone]

-Anyone who never made a mistake never tried anything new.
--Albert Einstein
View user's profile View All Posts By User
Hazard to Others

Posts: 163
Registered: 12-2-2007
Member Is Offline

Mood: No Mood

[*] posted on 25-9-2016 at 18:41

Analar is an excellent book for purity testing (I have the sixth edition)
View user's profile View All Posts By User

  Go To Top