Calculating USP Tailing factor

[EstebanLara09]

Hope this message finds you all well.
As my graduation project for attaining my degree in Pharmacy, I am developing a bioanalytical method for Vancomycin's therapeutic drug monitoring using HPLC. One of my goals was employing only Open-Source tools, like OpenChrom for the development and validation.

I am currently working with a HPLC-DAD instrument from Thermo, since this vendor's specific format isnt supported by OpenChrom I export my chromatograms (as single wavelenght) to .cdf format and analyse them using OpenChrom.

My problem comes at the analysis of my data. With Chromatogram Reports I can export response variables like RT, Peak Area, S/N, peak width at 0%, 10%, 15%, 50% and 85% of peak height in .csv format for the statistical analysis in R . However one of the problems I'm facing is with tailing factor A_S= (a+b)/2a; which requires data of peak width at 5% height. I know there are the parameters leading and tailing, but they are not what Im looking for (is there a way how are they calculated, so maybe through math I could get A_S?). Or is there a native way of calculating the tailing factor?

My current setup is:
OS: Linux Mint 22.3 x86_64
OpenChrom Version: 1.5.29
Build id: 20251017-0836

All help is welcome! Thanks in advance

[Mailaender]

Can you share a file in the format that is not supported together with a matching CDF?

[EstebanLara09]

Thanks for your prompt answer Matthias,
In the following link you can find the requested files:
https://drive.google.com/drive/folders/13WjX5cnIzSVwDbsyxHEmttNrANUyEGSB?usp=drive_link
I added an image with the software's available export formats and the corresponding files: .cmbx (vendor's), .gaml, .txt (single wavelenght and full spectrum) and .cdf.
Additionally, I added the chromatogram in .ocb with my current processing method (still working on it, suggestions are welcomed).

The exports were generated using Chromeleon 7.3.2

P.D. The cdf is recognized only as CSD, not as WSD.

[Mailaender]

The CDF sadly does not give away what type of chromatography it is except for the file name:

Right-click on it and choose the second entry in the Data Explorer to open as DAD data or use the GAML.

[Mailaender]

Next release will feature the peak width at 5%, of peak height #799.

[EstebanLara09]

Thanks for all the information provided, I assume I once installed my current version through flatpak, hence I was on version 1.5.29. Now I downloaded the 1.6.8 and now I can open GAML files and the calculations match my vendor's.

Regarding the original issue, the final goal was calculating the USP tailing factor A_S = (a+b)/2a = w₀.₀₅/2f. This addition enables the calculation of a+b (or w₀.₀₅) but the f portion is missing for now.

Looking through IPeakModel.java, ConfigurableReportWriter.java and ReportColumns.java, I consider f could be calculated through the following approach:

Get the peak maximum position via getRetentionTimeAtPeakMaximum()
Get all retention times via getRetentionTimes(), filtering to only those before the peak maximum
Walk up the front flank using getPeakAbundance(int retentionTime)
Find where the abundance crosses 5% of getPeakAbundance() on the leading side
Optional: Compute f = retentionTimeAtMax - frontCrossingTime and then compute USP tailing as w₀.₀₅ / (2f)

Or just computing for getting start(at 5% height)(a) and stop (at 5% height)(b) would suffice for doing the rest of the calculations (b-a)/(2*(RT-a)).

Needless to say, I am no computer scientist, just an enthusiast and a pharmacy student.
Really appreciate so-far given feedback and support.