MSN Home  |  My MSN  |  Hotmail
Sign in to Windows Live ID Web Search:   
go to MSNGroups 
Free Forum Hosting
 
Important Announcement Important Announcement
The MSN Groups service will close in February 2009. You can move your group to Multiply, MSN’s partner for online groups. Learn More
Chemistry Corner[email protected] 
  
What's New
  
  Welcome Page  
  About This Site  
  Message Boards  
  General  
  Inorganic  
  Organic  
  Pictures  
  Random  
  FOR ALL  
  Handy Symbols  
  Chemistry Humor  
    
  Documents  
  Chemistry Sites I  
  Chemistry Sites II  
  Chemistry Sites III  
  Organic Sites I  
  Organic Sites II  
  Analytical Sites I  
  Analytical Sites II  
  Lesson Plan Sites  
  Online Problems  
  Names & Formulas  
  Naming Exercises  
  Equations I  
  Equations II  
  Eq. Exercises I  
  Eq. Exercises II  
  The Mole I  
  The Mole II  
  Mole Exercises  
  Stoichiometry  
  Stoich. Exercises  
  More Communities  
  School's Out!  
  _________________  
  Site Map  
  
  
  Tools  
 
General : CE confusion
Choose another message board
 
     
Reply
 Message 1 of 3 in Discussion 
From: Jaom  (Original Message)Sent: 4/9/2008 3:35 PM
Hey!
 
In capillary electrophoresis two terms are often mixed. The litterature many times warns about mixing them, but never explain the differences.
 
In capillary electrophoresis, what is the difference between electrophoretic-flow and electroosmotic-flow?
 
In one place I read: When an electrical potential is applied on the column the ions start to migrate, cations toward cathode and vice versa. Electroosmotic flow.
And in another place I read: Electrophoretic flow is created when the voltage is applied.^10
 
 
 


First  Previous  2-3 of 3  Next  Last 
Reply
 Message 2 of 3 in Discussion 
From: MSN Nickname·Steve·Sent: 4/9/2008 4:52 PM
I was not familiar with the terms, but in the Wikipedia article on capillary electrophoresis, "electroosmotic flow" (EOF) is associated with the motion of the ions of the buffer and "electrophoretic flow" is associated with the motion of the ions of the analyte:

"Since the electroosmotic flow of the buffer solution is generally greater than that of the electrophoretic flow of the analytes, all analytes are carried along with the buffer solution toward the cathode."

"The velocity of migration of an analyte in capillary electrophoresis will also depend upon the rate of electroosmotic flow (EOF) of the buffer solution. In a typical system, the electroosmotic flow is directed toward the negatively charged cathode so that the buffer flows through the capillary from the source vial to the destination vial. Separated by differing electrophoretic mobilities, analytes migrate toward the electrode of opposite charge.[1] As a result, negatively charged analytes are attracted to the positively charged anode, counter to the EOF, while positively charged analytes are attracted to the cathode, in agreement with the EOF as depicted in figure 3."

"The velocity (u) of an analyte in an electric field can then be defined as:

up + uo = (μp + μo)E"

where up is the electrophoretic migration velocity of an analyte toward the electrode of opposite charge and uo is the velocity of the electroosmotic flow.  (See the article for definitions of the other terms.)
 
 
 
Wikipedia article on capillary electrophoresis:
http://en.wikipedia.org/wiki/Capillary_electrophoresis
 
Wikipedia article on electroosmotic flow:
http://en.wikipedia.org/wiki/Electroosmotic_flow
 

Reply
 Message 3 of 3 in Discussion 
From: JaomSent: 4/11/2008 4:00 PM
The first sentence really clearified everything. Thx again.