Shimadzu/Shodex/UC Davis

Record: 82

Category: Column Selection
Product:
Sample: poly lactic acid

Question
We will be analyzing poly(lactic acid) and poly(glycolic acid) over a large initial molecular weight range (2-300 kDa). The mobile phase will be THF and the flow rate will be 1.0mL/min. From the literature it appears that the temperature is 40C.I will be making blends of polymers of the various molecular weights so one sample will contain a wide variety of molecular weights. While I don’t need discrete, well-defined peaks for each of the starting polymers, I would still like some level of differentiation. I have included two very crudely drawn pictures to illustrate the point I was trying to make above. Another question I have is what is the low-end of the linear range of the LF-604 column?

Answer
I supposed that Michel has referred to you the following application
using our LF-604 column(analysis of poly lactic acid).
http://shodex.net/index.php?seitenid=1&applic=468
>> > You have mentioned THF, but the application uses chloroform and I am
wondering if you have a particular reason that you need to use THF instead
of chlroform.
>> >
>> > The guideline for the linearity of LF-804 (same pore size but the
larger id and length of LF-804) is 300 – 2,000,000Da.
>> >
http://shodex.net/data/downloads/Shodex_Technical_Notebook_1_LF_(GPC).pdf
>> > However since your MW range is between 2k-300kDa, I am thinking smaller
(mono)-pore sized column may provide a better resolutions. If you are
willing to use chloroform as a mobile phase, K-804 will be a better choice.
By using K series column, you do not need to replace the solvent from THF
(shipping eluent).
>> > Also 600 series columns require semi-micro type HPLC system (flow rate
of ~0.3mL/min) to provide the good separation and fast analysis, thus 800
series can be easier to handle (flow rate ~1.0mL/min).
>> > If you need to use THF, KF-804 will be a choice, but since we do not
have an application, I will need to check this with our application
specialist- so please let me know it.
>> >
>> > I would recommend our standard kit – SM-105. Containing 0.5g each of 10
different MW polystylene in the MW range of ~1k – 4,000K.
http://shodex.net/index.php?seitenid=1&reiter=r_results&prodid=1266
I have also checked few literatures and yes I see that KF column may be a
choice.
>
> Between KF-804 and KF-804L, it’s going to be your preferences.. obviously
KF-804L (linear, mixed-gel type) will provide a straighter calibration
curve, also better separation for the smaller, >1000 MW compounds. But the
slope of KF-804 is smaller, meaning may provide better separations (other
than smaller MW compounds).
> http://shodex.net/index.php?seitenid=1&applic=94
>

 
 
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