Page 1 of 1

theoretical plates

Posted: Thu Jun 02, 2011 2:33 am
by jackie1016
Hi, im having a little problem with my system suitability regarding theoretical plates. I am using Empower system for the calculation of my system suitability. In order for my system suitability to pass i need about 15,000 theoretical plates per meter. Im only getting 5562 in the USP Plates is this results in only theoretical plates per column? how can i convert it in theoretical plates per meter? Is there a way to convert plates per meter using the empower system?

Thank you so much.

Re: theoretical plates

Posted: Thu Jun 02, 2011 6:01 am
by DSP007
1) Yes, its plates in column
2) Its a "clinica" (acalculia) ... What is dimension of You column ? As variant => 250 mm = 0.25 meter.
15000/0.25=60000 tp
3)Read manuals (generate of reports )

Re: theoretical plates

Posted: Thu Jun 02, 2011 11:32 am
by unmgvar
jackie1016
plates per meter is almost never used anymore.
you find it mainly in old methods and litterature
I think mainly because it is simply a uncessary math transformation/extrapolation.
nobody really cares of that result because the effective plate count per column is what is important to us,
and actually it is a nice loophole for you to use any given column lenght if column specs are not well described in your method
not less than 15000 plates/meter=
for 25cm=3750 (not 60000, the shorter a column the less effective plates :wink: )
1/0.25=4 so 15000/4= 3750
for 15cm=2250
and so on :)

simply note to your self the plate per column necessary for your method and see in comparison for that value, because softwares these days mostly work with effective plates of the column because that is why user trully need to know.
if you are a GLP lab with SOPs see if you can insert that 15000plates/meter is same as 3750 (if you are using a 25cm column for example)
at 5562 plates for your compound you are fine

Re: theoretical plates

Posted: Thu Jun 02, 2011 11:51 am
by DSP007
No ,unmgvar
In my mean jackie1016 have 5562 really plates in real column.
And wants to know whether the 5562 dish on the column 15000 plates per meter.
That is, you have to share numder of really plates in the column length in meters.
And your version right. If that Jacqie column on 5562 p per meter, and she wants to know how much plates in a column? Then right- 5562 * 0,25= 1490 plates in column.
Or do you think that the USP has given the efficiency of a column, and in she passport "at the meter"?

Re: theoretical plates

Posted: Thu Jun 02, 2011 12:11 pm
by unmgvar
DSP007
USP plate count formula is
TP=16*(t/BW)^2
per column
jackie1016 wrote so: calculation using the USP formula in the software.

when in doubt ask, do not guess and perform incorrect statements.

Re: theoretical plates

Posted: Mon Jun 06, 2011 2:08 pm
by Alex Buske
unmgvar is right.
if you have 5000 plates per 1/4 m, how many plates do you have per m?