[Vorsim]

Hi there

Im currently doing a QA course and I am required to do a project. I have an idea about what to do the project on but I need some questions answered before I know if the idea is worth going through with.

Sorry if this is very vague I havent worked in the pharmaceutical industry in 5 years. I have an hazy recollection of someone telling me that in American plants, product left in the waste streams from ‘acid/base extractions’ is not recovered. To go into slightly more detail in the hope that someone will know what Im talking about; Product in organic layer – add acid – prdt is now in the aqeous layer – remove org layer – add more solvent – repeat the separation twice. Add base – prdt now back in org layer – repeat the previous steps in reverse.
The waste streams (not sure if organic aswell as aqueous layers are used) are stored over several runs of the product before being combined and the whole is acid base extraction is repeated before going through the crystallisation steps to end up with the final product. Again very hazy about this but I think this process was called secondary line or maybe stream??

So on to my questions .
Is it true that American plants dont recover product from waste streams? (if not this idea for a project is dead and the majority of this post was in vain ;p)
If true why is this the case?
Is it because of regulations and if so are plants outside the US not allowed to sell product recovered from waste streams? One reason I can think of that it might be regulated against is that since you’re combing waste stream from several production runs the traceability is adversly affected.
My poor memory recalls that person who told me gave the reason as being a ‘cultural’ that the product from waste streams is deemed somehow unclean even though its worked up to the same purity. This seems bizzare given the money being wasted.

Any help would be greatly appreciated and sorry for being so wordy and ignorant.

[Arkcon]

Briefly, no.  Sorry.  But to be honest, its a little hard to understand your application.  You've mentioned solvent extraction.  Fair enough.  People do 2 or 3 extractions, and that's for a reason, if you extract say 90% each time, you only get say, 90 + 9 + 0.9 after 3 extractions, there's no value in doing it more than that.  (damn, but I've forgotten the technical term for that.) 

I also don't understand your description of waste handling procedures.  First of all, aqueous waste and solvent waste are handled separately.  In many laboratories, aqueous waste travels through a lime pit, the layer of CaO produces a small constant amount of CaOH, which is a strong base, and precipitates metal ions, and other things.  Before release into the sewage system or the environment, the waste water is titrated, by an automated or manual method, to some neutral pH, say pH 6-9, the system can handle.  Solids are disposed of here. 

Solvents may be recycled by distillation, or burned. Again solid residues are disposed of as solid waste. 

The pH solvent extractions make for a good basic orgainic chemistry experiment, teaching a new student how to understand organic acids and bases.  But its not really big in industry.  For example: http://en.wikipedia.org/wiki/Solvent_extraction#Multistage_countercurrent_continuous_processes