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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: BioDude17 on April 13, 2008, 09:39:50 PM

Title: Solid Phase Extraction Question
Post by: BioDude17 on April 13, 2008, 09:39:50 PM

if you have a polar compound and need to make it non-polar, can you just adjust the pH? 

im really confused about the polar, non-polar, acidic, basic thing and what needs to be done to elute compounds with different properties - can someone please explain?

thanks a bunch!

Title: Re: Solid Phase Extraction Question
Post by: Arkcon on April 13, 2008, 09:49:55 PM

Sometimes you can adjust the pH and change the polarity.  If you look over some examples, you might figure out how it all works.  Let's try a few of your choice ...

Title: Re: ok 38 people viewed this post
Post by: BioDude17 on April 14, 2008, 09:36:47 PM

and NO ONE can answer my question?

Title: Re: Solid Phase Extraction Question
Post by: JGK on April 15, 2008, 07:56:23 AM

It's not that we can't answer it, we prefer to "help" you to understand the issues rather than "spoon feeding" you answers.

See the Forum Rules

Title: Re: Solid Phase Extraction Question
Post by: BioDude17 on April 15, 2008, 09:05:55 AM

ok well i have no recollection of receiving any help yet...so HELP me please!

Title: Re: ok 38 people viewed this post
Post by: Arkcon on April 15, 2008, 09:15:55 AM

Quote from: BioDude17 on April 14, 2008, 09:36:47 PM

and NO ONE can answer my question?

This forum has rules, that moderators are supposed to enforce.  I'm not a moderator, so I take a more subtle approach, giving hints about the topic at hand, trying to draw out a question, that leads to the answer.  So you'll learn what you need to know, and be better off when the exam comes.

I haven't been called 'nobody' before, on these forums.  'Though we do get our share of people who won't read their textbook, won't listen in class, won't apply general knowledge to specific examples, or ask pointed questions about a topic they're supposedly genuinely curious about.

In short, lots of people show up demanding complete answers so they have to do no work at all, and calling that behavior "getting help."  You've made one "gimmie all the info" posting, and two "help help" posts.  Do you actually consider that work?

Title: Re: Solid Phase Extraction Question
Post by: Alpha-Omega on April 15, 2008, 11:40:36 AM

Since your post is entitled:  Solid Phase Extractin Question, I am going on the premis you are trying to learn/determine the options available to you for the varuious types of analyses involved in SPE.  SPE is oftewn employed for selective sample prep in various chromatographic analyses.

This link may be of help to you (tremendous Chromatography resource for SPE):

http://www.chromatography-online.org/topics/solid/phase/extraction.html

Additionally, Sigma Aldrich and Supelco has a huge PDF which goes into the various theory/methodologies for various separations involved in SPE. Please see the following links.

Guide to Solid Phase Extraction: 
http://www.sigmaaldrich.com/Graphics/Supelco/objects/4600/4538.pdf

Supelco SPE Guide/Products:
http://www.sigmaaldrich.com/supelco/general_information/t402150.pdf