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Question about scaling up methods
Posted: Fri Mar 01, 2013 5:52 pm
by Mike H.
I have a method that uses a SB-aq 50mm x 4.6mm x 1.8µm column. There is an impurty that needs to be concentrated in order to do MS. I plan to use a similar C-18 column, 9.4mm x 250mm 5µm.
I planned to just use a scale up calculator to connvert the mathod to the new column, but after entering the parameters, the converted flow for the larger column is less than the optimal flow suggested by Agilent. 5ml/min-10ml/min. but the method calculator says to use 2.55ml/mim.
Is there a way to convert to larger column, use the recomended flow and still preserve the elution order?
Re: Question about scaling up methods
Posted: Fri Mar 01, 2013 11:05 pm
by tom jupille
What flow are you using on the small column?
Re: Question about scaling up methods
Posted: Mon Mar 04, 2013 1:15 pm
by Mike H.
What flow are you using on the small column?
50mm Zorbax C-18 aq 4.6 mm id, 1.8µm, flow 1.7ml/min. I'm trying to scale up and preserve selectivity to a Zorbax C-18 prep column, 250mm, 9.4mm id, 5µm.
I used one of the numerous scale up calculators on the net, but the scale up parameters generated state a flow of 2.55ml/min which is below the optimal flow of the prep column 5-10 ml/min. I don't know if this is because this method cannot be scaled up in a manner that preserves everything or if it's some error in the calculator.
Re: Question about scaling up methods
Posted: Mon Mar 04, 2013 1:53 pm
by AA
When I did the calculation for flow rate, I got 7 mL/min
Flow Prep= Flow Analytical X (Diameter Prep)Squared/(Diameter Analytical)Squared
Flow Prep = 1.7 X (88.36/21.16)
Flow Prep = 7.1 mL/min
Also, you dont need a 250 mm column for this, a 150 mm column 5um (packed with the same chemistry of course) should give you similar separation.
You can estimate the length needed for the prep column using this calculation Length/Particle size
50 mm/1.7um = 29.41
150 mm/5um= 30.00
A 250 mm column can certainly work, but wouldnt really be needed. Last thing, dont forget to scale the injection volume if you want similar chromatography.
Re: Question about scaling up methods
Posted: Mon Mar 04, 2013 3:51 pm
by HPLCaddict
The scale-up calculator used for the calculation obviously scaled not only to the column diameter, but also to the particle size:
7.1mL/min * 1.8µm / 5µm = 2.55 mL/min
I'd go with what AA said. Use 7 mL/min on that big monster, possibly using only 150mm length, if available.
Re: Question about scaling up methods
Posted: Mon Mar 04, 2013 4:49 pm
by Mike H.
This was helpful. Thanks