Chromatography Forum

We have recently purchased the new Chemstation Openlab software and a brand new Waters Alliance e2695 and the 2489 UV detector. My problem is that i ran a calibration curve and my peaks look good, but my area count is off by a factor of 10. For example, the area count for formaldehyde is 5.64 for level 1 in the cal curve (concentration is .0102 µg/mL.) Normally, my area count would be around 56.4 for level 1 with the same concentration.

Any ideas what is going on?

before anyone chimes in about why we did not by the waters software, it was the expense. We are a small lab.....it took me 15 years to get new software and equipment.....

Thanks for any help!!!

Is your signal-to-noise the same?

Good Afternoon,

Which Chromatography Data System are you comparing the current OpenLab against? Is the OpenLab for ChemStation Or Openlab for EZChrom the current one you're using?

Matt, he already said he purchased OpenLAB ChemStation, not the EZchrome ver,

You really need to provide more detailed info as we have little to go on. As noted, what are you comparing? Reports using the same methods on different instruments? If so, I would not expect the same results. An changes in instrumentation equals changes in results (esp detector setup). If only the control software was changed (same instruments), then you still need to check a few hundred instrument settings in the software which is something far easier to do in person and not via the web.

A dilution error by factor 10 can cause this. Did you prepare fresh samples (from the very beginning, inlcuding weigh-in).

Good luck
Jörg

Is your signal-to-noise the same?

Good idea, i will check the signal to noise ratio. Thank you!

Good Afternoon,

Which Chromatography Data System are you comparing the current OpenLab against? Is the OpenLab for ChemStation Or Openlab for EZChrom the current one you're using?

i'm comparing the Openlab CDS for Chemstation to the Chemstation Rev A. from 15 years ago..... (not the EZchrom version)

Matt, he already said he purchased OpenLAB ChemStation, not the EZchrome ver,

You really need to provide more detailed info as we have little to go on. As noted, what are you comparing? Reports using the same methods on different instruments? If so, I would not expect the same results. An changes in instrumentation equals changes in results (esp detector setup). If only the control software was changed (same instruments), then you still need to check a few hundred instrument settings in the software which is something far easier to do in person and not via the web.

Understood, thank you!

A dilution error by factor 10 can cause this. Did you prepare fresh samples (from the very beginning, inlcuding weigh-in).

Good luck
Jörg

Thank you, yes, we prepared fresh standards.

Hi,

I assume you are collecting the data via an analogue to digital converter as I'm not aware chemstation/openlab chemstation controlled any third party instruments?

If so check range and attenuation settings. It is not uncommon for digital areas to be different from analogue.

Hi Dr. Lott,
Thank you for responding, We do not have an analog to digital converter. The Chemstation Openlab software does control the Waters instruments. It's digital. Both companies have told me this will work!!

Double check your detector settings as your CDS may have sub-optimal defaults. Filter Time Constant: Normal, 2 sec., Data Mode Absorbance (not -MBF which is supposed to minimize gradient induced baseline curvature).

If these are right, try increasing your sampling rate. If that doesn't do it, a deeper dive into the Agilent side of things will be needed.

Are you aware of the fact that the integration algorithms used in ChemStation A rev and C and D Rev software are different? There are many changes in the software itself and the software release data provided with each version of software has a long list of changes. That said, your problem seems more likely to be a general parameter set-up issue (e.g. cal table, detector settings and so on) as there as many parameters which if set wrong can generate all kinds of errors. Why a simple thing as using the wrong or different signal bandwidth value can multiple or divide all the areas by a factor of ten. Changing the flow cell path length can also effect it to.

We have recently purchased the new Chemstation Openlab software and a brand new Waters Alliance e2695 and the 2489 UV detector. My problem is that i ran a calibration curve and my peaks look good, but my area count is off by a factor of 10. For example, the area count for formaldehyde is 5.64 for level 1 in the cal curve (concentration is .0102 µg/mL.) Normally, my area count would be around 56.4 for level 1 with the same concentration.

Any ideas what is going on?

before anyone chimes in about why we did not by the waters software, it was the expense. We are a small lab.....it took me 15 years to get new software and equipment.....

Thanks for any help!!!

Dear,
Please tell us whcih system you have used in the past, the system to which you are comparing the Area to. You say that you have an area 10-fold smaller, maybe the cell length of the detector is shorter for a start? Maybe the settings of the previous detector where different like having an amplifier setting differently??

Just thinking loud out here.