Chromatography Forum

Does anyone know where I can find a column with 7 um USP L21 (PS-DVB) packing, 300 mm x 7.8 mm. I need two with 50 nm pore size and one with 10 nm pore size, to be connected in series.

This was not my idea , I was just handed the method, from an in-process revision of a USP monograph. I have tried TSK, Phenomenex, Supelco and Waters and so far no luck with the exact phase and dimensions. As time is extremely tight, I would much prefer to use the method I've been handed than to attempt method development with an alternative column.

Thanks for any help anyone can give!

Stephen

Hamilton? Bio-Rad?

I'm guessing that the packing itself should not be too hard to find, but that the problem is in the column dimensions. USP allows "de facto" adjustments to conditions to meet system suitability. If memory serves, the allowed range is +/- 70% on length and +/- 25% on diameter.

Hamilton? Bio-Rad?

I'm guessing that the packing itself should not be too hard to find, but that the problem is in the column dimensions. USP allows "de facto" adjustments to conditions to meet system suitability. If memory serves, the allowed range is +/- 70% on length and +/- 25% on diameter.

Actually, the latest USP revision allows greater than +/- 25% on diameter (turns out that wan't enough to get from 4.6mm to 3.0mm to 2.1mm, etc.) as long as the linear velocity remains the same. From USP 32-NF 27: "Column Inner Diameter (HPLC): can be adjusted provided that the linear velocity is kept constant [see Flow rate (HPLC)]." For flow rate there is an equation.

This looks like a SEC/GPC application. If this is the case, do not change the column diameter or flow rates of the original procedure. The columns are available from Waters. I do not have the catalogue here, but inquiry for the microStyragel columns to Waters should help, if you can't find it in the catalogue or online yourself.

This looks like a SEC/GPC application. If this is the case, do not change the column diameter or flow rates of the original procedure. The columns are available from Waters. I do not have the catalogue here, but inquiry for the microStyragel columns to Waters should help, if you can't find it in the catalogue or online yourself.

I did not have any luck searching for it online, so I did exactly that and made an inquiry with a contact at Waters. Hopefully that might yield some results! I will also look into the suppliers Tom suggested.

The real kicker for me is pore size, given the type of application... I've really had terrible luck finding someone who can replicate the quoted dimensions. I fear that if I have to start experimenting with different combinations of particle and pore size I'm going to be getting into some serious development work. I do actually have some latitude if I needed it, but what I don't have, unfortunately, is time, particularly for a test widely regarded as more peripheral in terms of indicating product quality. I have a tight (I'm tempted to bandy around words like "insane" ) schedule, and to meet it I would love to just grab an already-developed method, verify that it works for me, and move on to the next thing.

Hamilton Company offers the PRP-1 (which is a USP L-21 packing) in those dimensions (7.8x305mm). It is a special order semi prep column. As far as I remember they are sold as 2 or 3 packs. The pore size is 100Ã… (=10nm). They do not have a 500Ã… (=50nm) pore size material. The closest would be the PRP-3 which has 300Ã… pore size. Not sure if that one is available in the column dimensions you need but I believe so (special order as well)
Delivery times for the PRP-1 columns is usually very short, even if they are special order.

Those packings are strictly speaking not GPC phases but regular polymeric RP phases.

good luck,

Robert

Thanks, Robert, I'll look in to that.

If you want a quick response from Hamilton send an email to:

scott.meikrantz(at)hamiltoncompany.com
and tell him Robert H. sent you.

he is the HPLC lab manager there and knows what is in stock and if it is not in stock how long it will take to get it out the door.

If you want a quick response from Hamilton send an email to:

scott.meikrantz(at)hamiltoncompany.com
and tell him Robert H. sent you.

he is the HPLC lab manager there and knows what is in stock and if it is not in stock how long it will take to get it out the door.

Done. Thanks very much for your help!

Apparently Waters makes almost exactly the right column (the product is available but no longer supported), with the right dimensions and pore sizes, the only problem is, it's available only as 10 um particle size . I have tried actually directly contacting the responsible party at USP (should have thought of that first, eh!) and maybe that will yield some answers. If the monograph calls for a virtually unobtainable column, I may have some comments on that, too

I've contacted the appropriate "responsible contact" listed in the USP monograph twice before, and the only thing contact did was to state "refer to <621> Chromatography.

On a different question when I asked why <611> used ACN as the internal standard for ethanol analysis instead of the more-similar n-propanol everyone else seems to use, contact response was that "no one questioned that when being reviewed". So I'm not so sure that the he really have that much hands-on experience, may just have "book learnin' ".

I've contacted the appropriate "responsible contact" listed in the USP monograph twice before, and the only thing contact did was to state "refer to <621> Chromatography.

On a different question when I asked why <611> used ACN as the internal standard for ethanol analysis instead of the more-similar n-propanol everyone else seems to use, contact response was that "no one questioned that when being reviewed". So I'm not so sure that the he really have that much hands-on experience, may just have "book learnin' ".

...and yet I live in hope that maybe, somehow, this time it will be different .

I'll let you know how that works out for me.

Happy news! Waters has the exact right columns, my contact there just had to do a lot of digging to find them buried deep in the darkest reaches of the catalog. She's sent me the part numbers. For the sake of anyone going through the same hell at some future date, the part numbers are:

50 nm: WAT010571
10 nm: WAT010570

These are the 7 um, 7.8x300 mm L21 PS-DVB (ultraStyragel is Waters's brand name), packed in THF. In fact, the particle sizes are a distribution between 5 um and 10 um centred around 7 um (if you go on the web site it will say 5 um), so I think these are exactly what I was looking for. I need to move quickly, so I'm just going to pay whatever they cost and carry on.

Still no word back from USP. I will follow up if I do hear anything.

Thanks for all the help and advice!

Stephen