Chromatography Forum

Hi ,
Anybody know how you quantify known and unknown peaks using EZchrom elite?
Calculating one peak assay results using external standards for example is not a problem using multipliers,diluter columns, but I cannot figure out how to quantify rel subs results, or if it is even possible
IE , how and where do you enter relative response factors or RRT to main peak.

I have used Empower Chromeleon, Analyst and Chemstation software in the past with varying success but calculating %w/w or % area of deg peaks for example I cannot figure out
Any info much appreciated

Ha, this is a bit tricky and you need to know the trick. Unknowns can be calculated. The trick is to create a non calibrated timed group, exclude named peaks, and assign the main compound ID (aka peak ID) as calibration reference and add a Mult Factor to adjust for the concentration.
Depending on where you are i can setup a wenex demo to explain to you.

Hi varossf,

Thanks for your reply.
Sounds like it is abit tricky!,, unlike previous software I have used
I understand some of what you are saying but not all.
What we normally have is known and unknown impurities, so we need to name peaks in peak table, and unknown peaks are usually named by RRT.
Unfortunately Wenex demo will not work we I am.
Any chance you could explain this further if possible (step by step,, thats say for one peak assay and one known impurity and unknown deg peak)
Any help much appreciated

are all your impurities, known and unknown, named in the peak table? I was referring to complete unknown peaks in the chromatogram.
If they are named it is easy to do

Hi varossf ,

Yes all peaks will be named by known name (impurty A ,B etc) or by RRT to main active in peak table (GMP enviroment)
Let me know what steps to take to quantify rleated substances using EZchrom elite
Again I am not sure how this is possible looking at the peak table and columns present

Thanks

Wil work this out for you, I am travelling at the moment so not easy to do this with screen shots, but calculating amounts of named peaks on the calibration of another upbeat is default functionality

Hi varossf .

Any information on this would be great so get back to me when suitable
Thanks again

OK, here we go in text, for images please send me a pm, email is in my profile.
In the peak table you will find that every compound has an unique identifier (compound ID), this is column "ID" just next to the "Name" column. This identifier is used in reporting but also as a reference to other compounds for e.g. RRT calculations, Reference Peaks and ISTD.
In the peak table you will find 2 columns that will address your questions.

Column "STD ID #"
In this column you need to specify the unique compound ID which against the impurity needs to be calculated. If specified the concentration of the impurity will be calculated on the base of the specified compound

Column "STD Mult."
Here in this column you can specify a correction factor for the impurity if necessary to compensate for a difference in response on the detector. If not then just specify 1.

Now your impurities will be reported in the right concentration.

Have fun!

... email is in my profile.
...

Your e-mail address is probably accessible only to you, not for forum users - or I can't find it
PM is switched off as well.

dblux_
it must be hidden, i added my agilent email address in my profile as text, see if you can find it

Still unavailable.
E-mail address field is empty as all other fields in "Contact section" of your profile

Interesting as I have activated all of these, PM, email etc so that people can contact me.
I even placed my email in the 'occupation' section of my profile.
Are you limited?

Now I can see it in your signature. I would take antispam measures and modify slightly e-mail address to cheat robots. (otherwise you may get plenty of spam every day).

Hi varossf,

Thanks for the update.
I have managed to calculate impurities by trial and error and with you update, thanks for that.

One further question. any ideas how you calculate dual actives (or 3 or 4 some cases) using Ezchrom Elite.
Onyl one level can be entered into sequence, and hence one calibration curve for one peak

Any thoughts

Not sure if I understand your question correctly. Concentration levels are specified in the method, up to 99 if you like. Then in the seuence you select the corresponding level for that standard. Hence you get your calibration curve. If you have not all compounds in one sample but across multiple and still want to calibrate then we better talk on the phone or email as I have not come across a calibration question I could not solve.