Capillary Electrophoresis (Part 2): Instrumentation & Electroosmotic Flow
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- čas přidán 23. 02. 2019
- This video is Part 2 of 6 for the e-Lectures series of NUS Chemistry CM3292 experiment titled "Capillary Electrophoresis (CE) of Inorganic Anions".
Contents:
0:18 Instrumentation of CE
3:01 Electroosmotic flow (EOF)
6:29 Unique flat flow profile of EOF
By the end of this e-lecture, students will be able to:
1. Describe the basic instrumental setup of CE.
2. Explain the origin of EOF in terms of the Surface Chemistry of the fused silica capillary, the fixed layer, and the diffuse layer.
3. Predict the direction of the EOF when an electric field is applied.
4. Compare and contrast the Flat flow profile of EOF in CE and the Parabolic flow profile of Pressure-induced flow in HPLC.
Thanks for watching :)
Presenter: Dr Francis Chong
Producer: Dr Francis Chong
Artworks: Madebyelvis
best explanation!
I was searching for hours before I found someone who could explain this so comprehensively! Thanks a lot and keep up the great work!!:)
I consider this videos the gold standard for CZcams technique explanation videos.
Hi @Amar Thaker, thank you very much for your kind words. :)
What an amazing video! Took me a while to find it, I love it! Every other video talks about biology and DNA…
Absolutely glorious! Thank you so much for this comprehensive explanation with great visuals to boot!
Very well explained and fantastic animation. Thanks. Keep up the good work and quality
I finally understand it. Thank you for amazing explanation and I love how all diagrams are colour coded.
Amazing video and great explanation!!! Thank you so much!!
Very well explained, thanks Francis.
Thank you for explaining the concepts so well ! 🌷
This is the best explanation of this I have EVER SEEN!!! EVERRR!! You are a magnificent human being! I am sharing this with my classmates and I am subscribing!
Hi @Bethany Todd, thanks for watching and subscribing. You are awesome! Thank you so much for your kind words. Glad that you find the video helpful :)
Excellent method to explain about capillary electrophoresis. Thank you
very informative!!
Thank you so much.
This video was amazing! Everything was explained so elegantly. Thanks!
@Ameya Kale Thank you :)
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Ecstatic love for your Comprehensive lecture on CE.☺️
Hi @Saad Ud Din, thank you. :)
Great video ! Thank you !
Nice editing, it was a pleasure to watch! Keep up the good work : - )
@1MoreStep Thank you :)
Finally all doubt clear..Thank you so much sir.❤
Really good explanation. thanks a lot
Great video thank you !
Caught me off guard at 06:09 with the Pokémon healing sound. Guess even Electroosmotic Flow needs a Pokémon Center visit to get its charge back up. Great explanation, thanks for the laugh!
Great! Thanks
You don't know how thankful I am for this well-explained video. I am going to present on this topic but I wasn't sure why bulk moves towards cathode even reading from different books I couldn't understand the basics phenomenon. You explained very well. Thank you once again. You have a wonderful teaching method. Could you please make a video on how Glass Electrode work? It is another topic on which I'm still confused and not sure how exactly the Glass Electrode works.
Hi @Greatest Lines, thank you very much for your kind words. Glad the videos were useful :)
FYI, I don't have plan for creating video on how glass electrode works yet, as it is not part of our syllabus for my students. I will definitely keep this topic and electrochemistry in mind in the future.
Great explanation. Thank you
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Great explanation!
Outstanding
Very well explained with animation. Thanks a lot!
Hi @Rana Zainuddin, thank you very much for your kind words. Thanks for watching :)
Thank u soo much I can never be grateful enough
No problem 😊 @amira mnd :)
thank you so much,! clear , easy understandable and detailed. I am preparing my biochemistry exam ... greeting from Italy!
Hi @Sasha Romagnoli, thanks for watching. Glad that you find the video useful. All the best for your biochemistry exam :) grazie
This video is excellent. I literally studied only from this video and got higher marks. Thanks
@Mirinal Ray, congrats on your high marks :) And thank you so much for the compliment :)
I will recommend my students to watch your videos. Nice explanation.
Hi @Dr. Nanda Gunawardena, thanks for watching. Sure, please feel free to recommend the videos to your students. Hope the videos are helpful.
thank you dr chong, now i can do my lab report 🤭🤭
You are most welcome, Kenneth! Thanks for watching!
great video
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This video is amazing!
@Khurshed Akabirov, thank you very much for your kind words. Thanks for watching :)
thank you ! can you explain what is the band braodening please?
This video help me a lot, thanks
You are most welcome @Socheata Heng :)
Finally a good explanation
Thank you, @Weijie Yao.
Many many thanks to you
Many many thanks to you too @Kumar Subham :)
Haha I loved your Pikachu icon!
Thank you Francis so much for this explanation! You have a lovely teaching method. You made this involved topic into an elementary one :)
You refer to another lecture in the video (2:45). Would you ever consider uploading that lecture as well? :)
Hi @Giorgianna Grant, thanks for watching. My apologies, for the topic on column chromatography (2:45), it was a face-to-face lecture for the students two years ago. I will keep this in mind, and might cover this topic in future videos. Thank you :)
You are amazing thank u ^^
Hi @rawan mohammed, you are most welcome.
Where can I find the reference "McDevitt, V. L.; Rodriguez, A.; Williams, K. R. J. Chem. Educ. 1998 75"??
I have two questions that are keeping me from fully understanding why the liquid move due to the electroosmotic force. 1. When I add up the number of ions in fixed layer, diffuse layer, and bulk solution, cations are greater in number than anions. But if pH is >7 shouldn't there be more anions? 2. Electrophoretic force only affects the mobility of ions, not the liquid. If the EOF moves the liquid and ions then why doesn't the EP affect the liquid but only the ions?
Hi @Jeffrey Kim, thanks for watching. Thanks for the questions.
1. In the case of normal EOF, the concentration of cations is higher than that of anions in the diffuse layer, which in turn influences the direction of the EOF. However, as compared to the bulk solution, the species in the diffuse layer is just a very tiny portion of the entire system. The total charge in the solution should always be balanced. For instance, if we were to prepare a standard chloride solution, we would probably dissolve a known amount of NaCl in ultrapure water right? So there will definitely be counter cations in the solution.
2. pH tells us about the concentration of H+ ions present in the solution, but not the concentration of anions present in the solution. Perhaps you may consider the relationship between pH and pKa? For more information, please kindly refer to: www.thoughtco.com/the-ph-and-pka-relationship-603643
3. Yes, electrophoretic mobility is usually only considered for charged species, but not the neutral species. Since the driving force is the potential difference applied, only charged species will be affected. For neutral species, the electrophoretic mobility is equal to zero. Perhaps you may also refer to my other videos relevant to capillary electrophoresis? Link: czcams.com/play/PLKuPzbjZoQ2i42DW_Ss7jCrcbHEgvaXDx.html
Haha better than my professor xD
Doesn't anions move to the anode?
Hello @sindu priya :) Yes, anions are attracted to the anode under usual circumstances. However, in the context of Capillary Electrophoresis, Electroosmotic Flow (EOF) is the major factor that governs the direction of the flow of the bulk solution. In this case, as illustrated in the video, the Diffuse Layer has higher concentration of Cations as compared to that of Anions, therefore when the voltage is applied, the Diffuse Layer will be attracted towards the Cathode, dragging the Bulk Solution (everything, including the cations, anions, and neutral species in the bulk solution) towards the Cathode.
In the context of the Electrophoretic Mobility, the anions are attracted to anodes. The Electrophoretic Mobility of the charged species (anions and cations) governs their separation in Capillary Electrophoresis. If you are interested in finding out more about Electrophoretic Mobility, please feel free to check out the 3rd Video on CE: czcams.com/video/XVeE-Lb0EPU/video.html
The overall migration rate (and direction) of individual analytes in the solution is equal to the sum of EOF and Electrophoretic Mobility. In general, EOF is greater than the Electrophoretic Mobility, therefore in the example mentioned in this video, even though the anions are attracted towards the anode (due to Electrophoretic Mobility), the resultant movement of the anions are still directed towards the Cathode due to EOF. On the other hand, in the case of Reversed EOF, the anions move towards the anode. If you are interest to find out more about Reversed EOF, please feel free to check out the 6th video of this e-lecture series: czcams.com/video/pP4kZlJYTyo/video.html
Thank you. And have a nice day, @sindu priya :)
@@FrancisChongYY thanks for the reply.. How abt coated capillaries where eof is ruled out
Sir plz upload other tool and techniques video
Hi @Avik Sarkar, yes, I will try to create more videos of other Instrumental Analyses during the winter break :)
2:57 because of what groups??? I don't get it.... can someone tell? like, aren't those hydroxide groups??
Hi @Khush Bakht Hassan. My apologies for the pronunciation at 2:57, I meant "silanol group", which is like a hydroxide group attached to a Silicon atom. Hope this clarifies. Thank you :)
@@FrancisChongYY ahh yess got it :D thank you so much :))
Great video but I don't understand the pronounsation of those silicon groups.
Hi @Karabo Ramosamo, thank you so much for your help clarifying the pronunciation for that part. Have a great day.
Watching this on 2024
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