Chromatography Forum

Dear All,

I have the following issue:
I have a four-component mixture which is analyzed by HPLC-ELSD. I do external calibration by injecting different volumes. I also do the same for the unknown samples. After the calibration, I always do the checking whether the compounds fall on the calibration range or not or the detector doesn't cut the signal.
I would like to write a custom field to have visible information about this information whether the analyzed compound fall into the calibration range or not. I know boolean or enumerated custom fields can work.

Unfortunately, I cannot identify "the calibration range and the maximum signal response of the detector" in the calculated formula entry. They are not in the list.

What I would like to see to have an extra column past the identified peaks with the following:
- Accepted
- Cut by detector
- Outliers (out of calibration range)

Do you have any idea ?

Thank you in advance!
Tomi

Hi ,
Maybe try using MAX( function with ENUM(EQ, LTE and GTE with value 0 = accepted , 1= Cut off and 2 = Outlier
Sorry not in front of Empower at the moment

Hy,

Okey, but how do you identify the signal limit of the detector and the actual calibration range (min and max) ?

Thanks !

You may have to find the max slice area from the raw data file - not sure what the field name for that would look like.

Hi,

Solution for the Outliers visualisation:

A.) Name: Border
Real 0.0) – Peak
Formula=Area

B.) Name:Accepted
ENUM - Peak
0 NO Outlier
1 YES Accepted
2 NO Outlier
Formula=ENUM(LTE(Border,Low..(Border)),RANGE(Border,Low..(Border),High..(Border)),GTE(Border,High..(Border)))

C.) Put "Sum custom Field" into the end of sample set table

D.) Update the report formula to see the calculated data

It works really well for fast checking at calibration (stock solution in one vial, different injections) + unknown samples (one vial; different injections).

Hi,

Solution for the Outliers visualisation:

A.) Name: Border
Real 0.0) – Peak
Formula=Area

B.) Name:Accepted
ENUM - Peak
0 NO Outlier
1 YES Accepted
2 NO Outlier
Formula=ENUM(LTE(Border,Low..(Border)),RANGE(Border,Low..(Border),High..(Border)),GTE(Border,High..(Border)))

C.) Put "Sum custom Field" into the end of sample set table

D.) Update the report formula to see the calculated data

It works really well for fast checking at calibration (stock solution in one vial, different injections) + unknown samples (one vial; different injections).

Do you know how the above formula can be implemented for more difficult determinations ?

Next problem: 4 compounds (each has diff. conc.) in the certified reference biological matrix; Different amounts are injected from vials due to the calibration and quantification (diff injec./vial)

Unfortunately, some compounds are outliers or cut off the detector because they have too high concentration.

How can we link or modify the above formulas appropriately ?

Also be aware of using intersample custom fields that don't specify the injection, for example A..(Amount) will only give the penultimate amount, so if you had 3 samples and all were labelled A, you get nothing for the first sample for this custom field and the second sample gives the amount for the first sample and the third sample gives the result for the second and so on.

To prevent this, either specify injection number or use the wildcard % to include all of the injections, so A.%.(Amount) or A.2.(Amount).

Plus be aware you don't need to use Summarize Custom Fields to calculate the above ENUM equation, you only use it when you have a summary function in your custom field for example AVE, MAX, MIN, %RSD and PROD.