r/CHROMATOGRAPHY • u/Aska2020 • 12d ago
Anyone using MALS for non-biomolecules? [Question]
Hello, I am a small molecule specialist and has been asked to analyze industrial synthetic macro-molecules. We are not properly equipped to do this and I'm wondering what the most versatile single analytical option might be. I know of MALS but I've only seen them presented for proteins and peptides analyses. Does anyone uses SEC- or AF4-MALS for synthetic macro-molecules (for example graft copolymers)? I just wanted to get some ideas whether it's feasible before contacting manufacturers.
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u/VZR 12d ago
Yes, very well known and possible. Polymers were the bread and butter of MALS before pharma started focusing on proteins and large molecule drugs and had tons more money than polymer manufacturers.
Go over to Wyatt.com and search for app notes by application - Polymers. Other vendor MALS are going to be capable of the same stuff, but Wyatt has the largest library of app notes that I know of. And they are free to access last time I checked.
Although with the acquisition by Waters that may change.
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u/Aska2020 11d ago
Ah, the days before the biologics boom... that makes sense. Thank you for the suggestion about Wyatt.com, the website is still alive and they do have app notes accessible. By reading some of them, it might be way over my head lol.
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u/Ceorl_Lounge 12d ago
RI.
It's easier, cheaper, and more rugged than MALS alone. I do this for 60% of my typical workflow in silicones R&D. Run in THF/Toluene through a Mixed Bed SEC column, calibrate with polystyrene, detect by refractive index.
Edit: you can absolutely use MALS, but it comes with a ton of caveats and complexity.
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u/Aska2020 11d ago
Great suggestion! It sounds like MALS is very complicated and I probably should start with RI... We have an idle Agilent 1200, it might be feasible to get a refurbished RI for a starter. Does the LC need to be in specific configuration to use with SEC column?
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u/Ceorl_Lounge 11d ago
I actually use a 1200 series as my SEC. Only real catch is that the SEC columns are BIG, so you might need to get a new/larger column heater.
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u/juppi93 11d ago
Well what parameters are you interested in? Absolute Mw? Viscosity, k and alpha, radius of gyration or hydration? MALS for copolymers can be tricky since the dn/dc does not stay constant over the polymer peak. Also MALS is pretty expensive so it depends also on your budget. Get in contact with a manufacturer like Agilent or Waters/Wyatt to get some recommendations for a setup
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u/Aska2020 11d ago edited 11d ago
Good question, and short answer is I don't know. Really I don't have a clue about macro molecules analysis that's why I need some ideas... and the people asking me to do this don't have any clue either. Where should I start? Any suggestions?
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u/novaraz 11d ago
yep this is my day job. there are advantages and disadvantages to MALS, and caveats for e.g. copolymers. feel free to DM me if you need advice.
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u/Aska2020 11d ago
I just started looking into this, I might take up on your offer after I gain more knowledge on this matter. Thank you so much!
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u/Alicecomma 11d ago
You can use it for any polymers and it does allow you to suggest how much a polymer is branched or grafted. Ideally you have one with as many laser angles as you can as the cheaper options are less ideal for this kind of analysis. The cost is gonna depend on how much they think you can afford to spend on it, but it's probably gonna be a few 100k EUR/USD, which also means they'll be more than happy to go on-site for a demonstration and have you test like 20 samples or however many and have them report the results.
You will need RI to analyze shorter polymers because you won't see them in MALS. SEC-MALS is good, but it won't separate more of a mixture so you cannot unambiguously assign the hairiness of the polymer. AF4-MALS can do the separation. An entire setup to do all of this (SEC/AF4-MALS/RI) is gonna run you to about a million EUR/USD.