Chromatography Forum

I've been trying to get some custom fields developed for our testing and am running into a problem with component fields. I have them created, but when I try to reference them in another calculation I do not get any result. I'm trying to make the fields so that I can put in information related to the standards (weight, potency, etc) and have them used in the calculation for the amount in my unknown samples. Does anyone have any tips on this? I can supply more information if needed.

Hi jhentzen,
This should work ok for you. Are you processing the samples after filling in the component custom field values? - sorry if it sounds a little basic, but empower is not proactive and if you created the fields after processing and have not filled in values, the new custom fields will also appear without any values. These will only be filled after reprocessing.

Otherwise, perhaps look at the fields that are referencing the component fields - could you describe these (for example peak type? formula? etc...)...

I am processing the samples after filling in the custom fields.

I have looked at the field referencing the component fields, which I'm pretty sure is where it is having an error. I've made the formula as simple as I can (=amount*stdweight) with stdweight being the component field and get no result.

I've tried taking all my standard values (the component fields) and putting them into the value area in the component editor and that does give me a value. Should I just do that instead? Ideally I was wishing that I would not have to do any calculations, and just be able to put in the actual information and have empower do all the calculating for us.

There is no "=" in the formula...maybe that will help?

I have mine set up to enter the std wt under "Value" in the component editor..I didn't make a custom field for it. Also make sure your processing method is set to AMOUNT and not concentration maybe in THAT component editor?

Also...aren't amount and std weight the same thing??? Why are you multiplying them?

Sorry I didn't finish reading your post...
Ok so what you did in the last part sounds right, you enter all of your standard weights in the component editor of the sample set method. When you run your samples, as long as you enter the weight of the sample and the dilution factor and leave these fields "1" for the standard injections you should be fine. I also have a Standard_Purity field here (in the sample set method) where I enter the purity and then a custom peak calculation (Amount*Standard_Purity) that gives the final result in %w/w.

Empower should be calculating everything for you already based on your post.

Your custom fields should work, but I think you may be missing something;
here are a few pointers - bear with me on the simple stuff as it may highlight something:

As cody84 said, the values still need to be entered into the value fields in the components table for Empower to calculate the Amount field. The referencing custom fields then use this Amount field with the factors entered into your component fields.

When referencing fields, the spelling and capitalisation must be correct. Your example should read Amount*stdweight in the custom field.

Your referencing custom field will be a peak type field and will be found in the peaks table (under the chromatogram in the review main window). The field will only be populated for standards or samples where you have filled a value for both your new component field and the value field as both are used. The new custom field does not alter the value reported in Amount.

As mentioned, you can also use the SampleWeight and Dilution fields that are sample fields built into Empower. These alter the Amount returned by Empower.
For Standards: The software will divide the standard amount or concentration values by the Dilution field and multiply the amount or concentration values by the SampleWeight field (entered for that standard).
For Samples: The reverse is the case. The software will multiply the sample amount or concentration from the calibration curve by the Dilution field and divide the amount or concentration from the calibration curve by the SampleWeight field (entered for that sample).

SampleWeight and Dilution fields were originally designed to be used for samples or standards to account for dilution and sample losses, but you can use them as factors as you see fit.

If all the above is OK and you’re still not getting values, then troubleshoot your field by starting very simply. Create reference fields:
Amount (to double check your reference to this field),
stdweight (to double check your reference to this field),
and then
Amount*stdweight

If that does not work… drop me a line ben.w@mvc-consult.com and we can see what is wrong…