@@MalvernPanalytical thank you. I have read your replies to other questions and I found them very helpful. You are truly the experts (and very kind people too). Thank y o u again.
In gpc chromatogram there is a solvent peak always, why ? How can we explain it ? Because in HPLC there is no solvent peak. Thanks for this informative video....
The chromatograms obtained from GPC/SEC typically have a solvent peak in the refractive index detector’s response. This is because it’s a differential refractive index detector, and a comparison is made between the blank solvent in the reference cell and the solvent, and anything else present at the end of the chromatogram. The RI detector is very sensitive to slight differences between solutions, and the difference between the solvent in the dissolution solvent and mobile phase is usually enough to produce a response. Solvent peaks aren’t as strong in other detectors. UV detectors only see molecules with a UV active chromophore, which most solvents do not possess. The light scattering detector responds to a sample’s molecular weight, and since solvent molecules are all small, discrete molecules the differences aren’t detected. And a viscometer observes changes in solution viscosity, which isn’t usually that different between the mobile phase and the dissolution solvent.
I think most HPLC systems use a UV detector, which is why there is usually not a solvent peak.
There is a little more info on what creates solvent peaks near the end of this post.
Great video! How do they control the pore sizes in the particles that are inside the column? Are the different pore sizes controlled through polymerization?
Thanks very much for the positive feedback. To answer your question, the particle sizes and pore sizes are controlled through polymerization. For example, polystyrene divinylbenzene (PS-DVB) the pore size is controlled by copolymerization process (addition of divinylbenzene). Moreover, a catalyst may be used to increase polymerization rate. Much like crystallization the particle size and “tightness” of the particle (i.e. pore size) can be controlled by the rate. The MW and volume is usually a range that approximates a Gaussian distribution. Thus, afterwards, we need to characterize and cut the high end and low end of the distribution. This is a physical process. Also, the column solvent may swell or shrink the particles and pores and we adjust the manufacturing technique to account for this. The reported particle and pore size is usually an average. “
Here is the reply from our specialist Thanks for sharing the compliment. There is a lot of information on how to operate the instrument available on our GPC/SEC Expert Advice playlist: ruclips.net/p/PL2wIBTZfZRjd7tyhnBRy2xLhToO3CCcY9
Hello, and thanks for the question. You are correct that Malvern Panalytical no longer manufactures HT-GPC systems. While we can't make a recommendation due to lack of experience with non-Malvern Panalytical systems, Agilent offers a multi-detector HT-GPC system and Tosoh offers a RI-only HT-GPC system. I hope this helps!
Hello ! i don't understand why you're saying that it's based on hydrodynamic size , not in molecular weight ? because i thought it was all a weight matter ....thanks to your answer
Hello, GPC separates based on the hydrodynamic size of the molecules, small molecules will spend longer in the micro-pores of the GPC column than larger molecules, which are more physically restricted from entering. Thus GPC separates based on the size of the molecules, there is (or shouldn’t be any) chemical or physical interaction of the sample with the column. GPC is used to determine molecular weight, traditionally by the elution time/volume of your sample compared to that of a set of standards of known molecular weight. This method assumes that your sample has the same molecular confirmation/density as your standards and therefore an increase or decrease in size relates to a corresponding increase or decrease in molecular weight. This type of conventional calibration is therefore error prone as you sample may not have the same confirmation or density as that of your standards. Hence why Malvern advocate the use of static light scattering detectors to measure the absolute molecular weight of the sample, free of the size - molecular weight assumptions that conventional GPC relies upon. I hope that the above answers your question. However, if there is anything else that we can assist you with, feel free to contact us directly at your convenience. www.malvern.com/en/about-us/contact-us.
Thank you for your interest, We thought that you'll be interested in the document below: White papers: "Static Light Scattering technologies for GPC - SEC explained" www.malvernpanalytical.com/en/learn/knowledge-center/whitepapers/WP130627SLSTechnologiesGPCSECExplained.html "Principles of Triple Detection GPC/SEC" www.malvernpanalytical.com/en/learn/knowledge-center/whitepapers/WP151119PrinciplesTripleDetectionGPC.html "Size Exclusion Chromatography / Gel Permeation Chromatography: An Introduction in 30 Minutes" www.malvernpanalytical.com/en/learn/knowledge-center/whitepapers/WP150625IntroToSECGPC.html Kyle also did a blog - www.materials-talks.com/blog/2016/08/30/an-introduction-to-gel-permeation-chromatography-in-30-minutes/ . You can search for various blogs that will list relevant content that can help you understand better our technologies Happy learning!
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Such a great video, it covered every aspect I needed to know!
Glad it was helpful!
Thank you, great video. Need to watch it few times to remember all the details. 🙂
Thank you for your positive feedback. Contact us if you need more information - www.malvernpanalytical.com/en/about-us/contact-us/
@@MalvernPanalytical thank you. I have read your replies to other questions and I found them very helpful. You are truly the experts (and very kind people too).
Thank y o u again.
You're welcome. are you aware of our blog as well? www.materials-talks.com/
@@MalvernPanalytical I haven't been aware but will definitely have a look. Thank you.
Very, vey didactic and useful! Thank you so much!
Thank you Josué
Very useful, thank you.
Thank you for your comment.
video bala, ajudou mt
Thank you :)
You're welcome!
Thanks
Welcome
thank you so much, It's really useful for me^^
Glad to see that you like our video.
In gpc chromatogram there is a solvent peak always, why ? How can we explain it ? Because in HPLC there is no solvent peak.
Thanks for this informative video....
The chromatograms obtained from GPC/SEC typically have a solvent peak in the refractive index detector’s response. This is because it’s a differential refractive index detector, and a comparison is made between the blank solvent in the reference cell and the solvent, and anything else present at the end of the chromatogram. The RI detector is very sensitive to slight differences between solutions, and the difference between the solvent in the dissolution solvent and mobile phase is usually enough to produce a response. Solvent peaks aren’t as strong in other detectors. UV detectors only see molecules with a UV active chromophore, which most solvents do not possess. The light scattering detector responds to a sample’s molecular weight, and since solvent molecules are all small, discrete molecules the differences aren’t detected. And a viscometer observes changes in solution viscosity, which isn’t usually that different between the mobile phase and the dissolution solvent.
I think most HPLC systems use a UV detector, which is why there is usually not a solvent peak.
There is a little more info on what creates solvent peaks near the end of this post.
www.materials-talks.com/blog/2018/08/22/what-is-a-dndc-value-and-why-is-it-important-for-gpcsec/
Great video!
How do they control the pore sizes in the particles that are inside the column? Are the different pore sizes controlled through polymerization?
Thanks very much for the positive feedback. To answer your question, the particle sizes and pore sizes are controlled through polymerization. For example, polystyrene divinylbenzene (PS-DVB) the pore size is controlled by copolymerization process (addition of divinylbenzene). Moreover, a catalyst may be used to increase polymerization rate. Much like crystallization the particle size and “tightness” of the particle (i.e. pore size) can be controlled by the rate.
The MW and volume is usually a range that approximates a Gaussian distribution. Thus, afterwards, we need to characterize and cut the high end and low end of the distribution. This is a physical process. Also, the column solvent may swell or shrink the particles and pores and we adjust the manufacturing technique to account for this. The reported particle and pore size is usually an average. “
It's really insightful. I have just started to operate the GPC instrument. Can you make a video about how to operate this instrument?
Hello, I'll ask our specialists about this video idea. Thanks
Here is the reply from our specialist
Thanks for sharing the compliment. There is a lot of information on how to operate the instrument available on our GPC/SEC Expert Advice playlist:
ruclips.net/p/PL2wIBTZfZRjd7tyhnBRy2xLhToO3CCcY9
This really helped me a lot! thank yu soo much
Glad to hear that you found this video useful. We have several of them available on our RUclips channel.
@@MalvernPanalytical ok
I know you no longer make high temperature systems for polyolefins - can you recommend a good high temp gpc system?
Hello, and thanks for the question. You are correct that Malvern Panalytical no longer manufactures HT-GPC systems. While we can't make a recommendation due to lack of experience with non-Malvern Panalytical systems, Agilent offers a multi-detector HT-GPC system and Tosoh offers a RI-only HT-GPC system. I hope this helps!
Hello ! i don't understand why you're saying that it's based on hydrodynamic size , not in molecular weight ? because i thought it was all a weight matter ....thanks to your answer
Hello,
GPC separates based on the hydrodynamic size of the molecules, small molecules will spend longer in the micro-pores of the GPC column than larger molecules, which are more physically restricted from entering. Thus GPC separates based on the size of the molecules, there is (or shouldn’t be any) chemical or physical interaction of the sample with the column.
GPC is used to determine molecular weight, traditionally by the elution time/volume of your sample compared to that of a set of standards of known molecular weight. This method assumes that your sample has the same molecular confirmation/density as your standards and therefore an increase or decrease in size relates to a corresponding increase or decrease in molecular weight. This type of conventional calibration is therefore error prone as you sample may not have the same confirmation or density as that of your standards. Hence why Malvern advocate the use of static light scattering detectors to measure the absolute molecular weight of the sample, free of the size - molecular weight assumptions that conventional GPC relies upon.
I hope that the above answers your question. However, if there is anything else that we can assist you with, feel free to contact us directly at your convenience. www.malvern.com/en/about-us/contact-us.
Malvern Instruments thank you very much , i'm now working on some concerning project , i'll contact you thank you 👍
@@MalvernPanalytical tak paham.
It's really useful for me, Can I get powerpoint form for your?
Thank you for your interest,
We thought that you'll be interested in the document below:
White papers:
"Static Light Scattering technologies for GPC - SEC explained"
www.malvernpanalytical.com/en/learn/knowledge-center/whitepapers/WP130627SLSTechnologiesGPCSECExplained.html
"Principles of Triple Detection GPC/SEC"
www.malvernpanalytical.com/en/learn/knowledge-center/whitepapers/WP151119PrinciplesTripleDetectionGPC.html
"Size Exclusion Chromatography / Gel Permeation Chromatography: An Introduction in 30 Minutes"
www.malvernpanalytical.com/en/learn/knowledge-center/whitepapers/WP150625IntroToSECGPC.html
Kyle also did a blog - www.materials-talks.com/blog/2016/08/30/an-introduction-to-gel-permeation-chromatography-in-30-minutes/
. You can search for various blogs that will list relevant content that can help you understand better our technologies
Happy learning!
Thank you so much! I hope you alway full healthy!
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🙏😁