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Empower 3 Technique (CF or basic Functionality)

Discussions about chromatography data systems, LIMS, controllers, computer issues and related topics.

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Hey I am trying to execute the following. Can you help me out?

Subtract a blank chromatogram from standards and samples
Following the subtraction, corrected individual peak areas will need to be used for quantification
As one of the peaks that is being subtracted from the standard is used for a signal-to-noise calculation, the signal-to-noise would need to be calculated based off of the corrected height of the peak.

Can E3 do this without a derived channel and CF? If not what is the best recommendation?

Cheers
You are able to do this, but you must use a specific derived channel for the blank.

I do not know if that is going to be a deal breaker for you or not.

There are more complicated ways to do this without the use of a derived blank channel via several custom fields. But, this approach is very complicated. However, I have coded a dual channel analysis in the past where the largest peak in each channel was reported. Subtracting a blank would be very similar.

If the derived channel is a go for you, please let me know that exact version of Empower you are running (e.g., Empower 3 FR2 SR1) and I can try to help you out.
Empower 3 FR2 HF1 SR2 HF2
Sorry for the delay in my response.

Select your method set and open it. Highlight Derived Channels in the left side of the window pane. Right click and select New and Derived Channel. This will open a new window.

In the First (Only) tab select your data channel from the drop down Channel list. Do not alter the constant to the right of the channel list.

In the Second Channel tab, select "-" as the operator and select the same channel you did on the previous tab. Again, do not change the multiplier to the right of the channel list.

Click the From Injection Labeled box located slightly below the multiplier. In the box specify the label BLK.

Use the BLK label as a sample label in the sample set of your sequence for one of your blank injections.

The above ought to accomplish what you are after without the use of custom fields.
Hi Shaun,

We think it is an order of operations think. I can't figure out how to attach a screen grab of the Alter Sample, but we are clearing calibration, calibrating , quantitating and summarizing CFs at the end of the SS.

The drived channel does subtract the blank but we can't get the correct CFs and basic calcs to work.
Is there a way for you to post the specific custom fields?

You may need to lock them down to do specifically what you want.

For example, sample Peak A minus Blank Peak B:

Use SMP1 .. SMP9 for your sample labels. Use BLK for your blank label.

SMP?.%.%.AVE(Peak A[area]) - BLK.%.%.AVE(Peak A[Area])

If you are only using one replicate each and are worried about that AVE function; its needed because AVE is one of the special operations required in a summary function type custom field. This will not average all SMP labels together as one. The field will run line by line in your sequence.

If you have two replicates, they will be averaged, if you use SMP1 twice then those two samples will be averaged.

Does that help any?
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