Chromatography Forum

Hello everyone,

Dear community, I'm sending you an SOS.
As I'm currently working on solving custom field problems, I find myself totally helpless when faced with these.

Here's the initial problem
We have 3 formulas:
a content calculation that includes the y-intercept
(1) Concentration = (average area - b / a ) *FD (=> b=A in empower)
As it happens, when the average area is less than b, the empower calculation doesn't work (there's no value in “amount”).

(2) %= Cconst1/ C (where Cconst 1 is the LOQ)

(3) concentration via empower with AVE(amount)

The aim is to make the link between the formulas: roughly speaking, if less than b, then apply formula 2 if greater than b, apply formula 3.

We've tried CuFi :
(LT(Area,Ordonnée_Origine)*formule 2)+ GTE(Area,Ordonnée_Origine)*formule 3)
where ordonnée_origine is a CuFI text for A

“ENUM(LT(Area,ordonnée_origine),GTE(Area,ordonnée_origine))
0 = formula 2 (fc)
1 = formula 3 (fc)”

We also tried to create an intermediate CuFi
Inf_ordonnée = REPLACE(Amount,CConst1)
CuFi works, then apply formula 2
and it doesn't work.

I've been trying out different combinations for several weeks now, so do you have any idea why the Custom fields don't work? And how to solve my problem?
Don't hesitate to ask me for more details if it's not clear. I hope you'll be able to shed some light on the subject, as I'm getting the impression that I'm in the wrong place.

Many thanks in advance for your help.

Hi, can you give an example of your sample set and what values in the calibration curve/component editor etc you are using? I may be able to help but I need a deeper look at the individual parts of the formula.

Hi, can you give an example of your sample set and what values in the calibration curve/component editor etc you are using? I may be able to help but I need a deeper look at the individual parts of the formula.

Hi thank you for your reply, I have finally find another way by using a REPLACE inside my formula : GTE(REPLACE(Amount,0),CConst1)*formula 1+LT(REPLACE(Amount,0),CConst1)*formula 2. Then it works !

I have another Custom that need to be create. It's only an average(Amount)
However, I need the average between the two concentrations of sample or internal control injections. Do you have any ideas on how to create it? Something like average_amount = average(amount inj1;amount inj2)