Custom Field for API in Label Claim as % and mg/mL

lczenith

Question 1: how create a CF for API in Label Claim as % and mg/mL?

Question 2: how calculate de amount in % of the Control standard according to the follow sequence, I mean recovery when compare with standard?

 

API (µg/mL) = (Asmp / Astd) * Cstd * (Wstd * P * Dstd * M1) / (100 * M2)

 

Sample Explanation of Variables:

• Asmp: API area obtained with each sample injection as label
• Astd: API average areas obtained with standard solution
• d: Density of the sample (g/mL) 1.20 g/mL
• Dsmp: sample dilution (mL) 20 mL
• Wsmp: mass weighted (g) 1.0 g

Content of API: 1.5 mg/mL.

 

Standard Explanation of Variables:

Note: the standard informations were included in the “components”

• Cstd: API concentration in standard solution (mg/mL)
• Wstd: API standard weighted mass for standard solution (mg/mL) (Preparation: 30 mg into 50 mL and 1 mL to 10 mL. final concentration 0.06 mg/mL)
• P: API standard potency (%) (99.9 %)

 

 

Sample name	Injection	Sample Type	Sample weight	Dilution	Density	Label Claim
Standard	1	Standard		500
Standard	2	Standard		500
Standard	3	Standard		500
Control Standard	1	Control		500
Control Standard	2	Control		500
Sample 1	1	Unknow	1	20	1.2	1.5
Sample 1	2	Unknow	1	20	1.2	1.5
Sample 2	1	Unknow	1	20	1.2	1.5
Sample 2	2	Unknow	1	20	1.2	1.5
Control Standard	3	Control		500

 Thank you.

Jovvor

Hey Iczenith
For your recovery of your standards you could make a simple custom field
Peak , Real, with formula Amount/Control Value*100
That will give a result in percentage recovery of your control standard against the standard calibration curve.

For your label claim. i would recommend using CConst1 up to 7 to put in your label claim in ug/mL for the corresponding component.
Than make a custom field which will compare your API(ug/mL) with your label claim.

Custom fields like:
Peak,Real with formula:API_ug_mL/CConst1*100 to get this in %
Peak, Real with formula API_ug_mL*1000 to get the resuls in mg/mL

lczenith

Hi Jovvor, thank you for answer,


The default formula of Amount is: AREA(SAMPLE)/AREA(REF)*VALUE(REF)*PURITY(REF)/SAMPLEWEIGHT(SAMPLE)*DILUTION(SAMPLE)?

What about the CF for sample amount using the density? Is it correct use the AMOUNT*Density? Density from the sample set.

Thank you in advance.
Lucas.

Jovvor

you could interpret the default formula as
AREA(SAMPLE)/AREA(REF)*VALUE(REF)*SAMPLEWEIGHT(REF)/DILUTION(REF)*PURITY(REF)/SAMPLEWEIGHT(SAMPLE)*DILUTION(SAMPLE)

from that amount you can indeed work further with your own created custom fields.
Like Amount*Density

A tip from Waters. If creating custom fields always use underscore and two words. eg Sample_Density as waters will never create custom fields like this as default in empower.
If Waters decide to create a Density field and incorporate it in some formula. if you update and have the same field allready present in empower it might mix up data and you will get wrong results or maybe even system crash.

lczenith

Hi Jovvor,

Thank you again. I would like to know if it is possible to create a CF for the real concentration? Conc real= (Area (SAMPLE) * Standard Concentration)/ Area (Standard).

Thank you.

Empower2019

For that, you could create a peak, real CF and have a formula of (U%.%.(Area)*CConst7)/Std.%.(Area)

For this to work, label your samples as U1, U2, U3 etc or U01..etc as long as it begins with U. Then your standard injection should be labelled as Std. If you are using all 3 standards as per your screenshot then the formula changes to:

(U%.%.(Area)*CConst7)/Std.%..AVE(Area) and make sure to put Summarize Custom Fields as the last line of your sample set. Put the standard concentration in CConst7 of the processing method. 

Jovvor

you could also make a backwards calculation
Peak,Real, formula: Amount*Sampleweight/Dilution

Empower2019

@ Jovvor, I think if you do that though, the 'Amount' value is going to be affected by the values in Sampleweight and Dilution. Amount is calculated by area sample/area standard * Value (component editor) * Dilution/Sampleweight. If you wanted to multiply the final amount by another value, you could create a Sample, Real CF and call it Numerator and Denominator and then the CF becomes Amount*(Numerator/Denominator). Otherwise your amount will be affected by values in Sampleweight and Dilution and be incorrect. 

lczenith

Hi, thanks for all the answers. Were very clearly. 

Jovvor

@ Empower2019.
I understand your point, but Amount allready incorporates the sampleweight and dilution factor.
So if you want the Conc real (Conc real= (Area (SAMPLE) * Standard Concentration)/ Area (Standard)), you could run the calculation backwards. 

if any values in sampleweight and dilution for your samples are set in the sequence the Amount will be calculated with them and the backwards calculation without the sampleweight and dilution of your samples.

Or I am misinterpreting the question.

lczenith

Hi, I was looking back the amount calculation and I am wondering what mean the "Value(ref)"?

AREA(SAMPLE)/AREA(REF)*VALUE(REF)*SAMPLEWEIGHT(REF)/DILUTION(REF)*PURITY(REF)/SAMPLEWEIGHT(SAMPLE)*DILUTION(SAMPLE)

Empower2019

Value is the inbuilt custom field in the component section of your sample set. In here, you typically enter either standard weights or standard concentrations for your components. 

lczenith

Hi, thanks for the answer, but I am trying to figure it out the same answer from the amount calculation.

For example: 
AREA(SAMPLE): 7409554
AREA(REF): 7494634
VALUE(REF): 63.18 mg, here I am completing with standard weights, I just want to make sure because in SAMPLEWEIGHT (REF) I am kipping 1 as show the figure.
SAMPLEWEIGHT(REF): 1
DILUTION(REF): 25 mL
PURITY(REF): 0.997
SAMPLEWEIGHT(SAMPLE): 1.051 g
DILUTION(SAMPLE): 20 mL

Thanks 

Empower2019

Based on your figures above, if you wanted to calculate Amount in sample then how Empower will do this is: 

Area of sample (7409554) / Area Ref (presuming Ref is designated as a Standard in the Sample Set) (7494634) * Value (63.18) * Purity (note if you put 0.997 in the Purity tab then Empower will divide this value by 100 when Amount is being calculated so 0.997/100 which is 0.00997, so if the purity of the standard is 99.7, put 99.7 in Purity * Dilution (25) /Sample Weight (1.051g but should convert to the same units as standard weigh so mg so 1051) This is 1.48133645597416 mcg for Amount. 

Rather than using the Sampleweight and Dilution fields for the standard injections, it may be more efficient to already have the final concentration of the standard entered into the Value so that way you take out the need to put in Weights and Dilutions. So your standard is 63.18 in 25 mls so 2.5275 mg/mL or 2527.5 mcg/mL. 

lczenith

Thanks @Empower2019, so I think is missing the sample dillution (20 mL), but I am still traying and gives me a different result.

Area of sample (7409554) / Area Ref (presuming Ref is designated as a Standard in the Sample Set) (7494634) * Value (63.18) * Purity (99.7) * Std Dilution (25) /Sample Weight (1051mg) * Sample Dilution (20 mL).