In shimadzu peak purity index for every sample and standard compound shows in minus. Event though Purity of the drug is 0.998 %. So is there anyway to adjust the peak Purity issue by adding reference chromatogram.
Thank you for your suggestion
You do not "adjust" the peak purity. You input the correct settings and parameters (which include reference spectra) for the software feature to use on the data file that you collected.
For more information: "Peak Purity Determination by HPLC Diode Array Chromatography Software: Limitations and Uses"; https://hplctips.blogspot.com/2016/12/peak-purity-determination-by-hplc-diode.html
Basically: You must start with a clean HPLC analysis / method which demonstrates good chromatography fundamentals have been followed. This includes proper K prime values to demonstrate the method is selective for the compound of interest and also that all compounds (impurities and other components) are seen in the UV/VIS region used. A nice clean and flat baseline is needed with properly chosen integration events. Next, peak purity settings must be input which are specific to your method (never use the "default" values in the software, many of which are simply there as field place-holders). These include the choice of reference spectra for the peak (usually a minimum of two different Rt's are used). One reference Rt should be selected in a 'clear' zone (where no peaks are observed or detected) before the peak of interest elutes and the second reference Rt should be selected for a Rt after the peak has eluted (again, in an areas where no peaks are detected). These help to establish the baseline reference of the spectral data which will be used for the peak (poor reference choice equals invalid purity data). If you are using a gradient analysis, the accuracy of the results obtained may be of lower quality than if an isocratic analysis is used (due to the change in the spectra that occurs with the change in solvent composition over time).
In fact, as used by most, this "Peak Purity" software feature does not measure peak purity at all. Diode-Array based 'Peak Purity' determination by HPLC is a qualitative assessment of the impurity profile of the sample, not the purity.
You do not "adjust" the peak purity. You input the correct settings and parameters (which include reference spectra) for the software feature to use on the data file that you collected.
For more information: "Peak Purity Determination by HPLC Diode Array Chromatography Software: Limitations and Uses"; https://hplctips.blogspot.com/2016/12/peak-purity-determination-by-hplc-diode.html
Basically: You must start with a clean HPLC analysis / method which demonstrates good chromatography fundamentals have been followed. This includes proper K prime values to demonstrate the method is selective for the compound of interest and also that all compounds (impurities and other components) are seen in the UV/VIS region used. A nice clean and flat baseline is needed with properly chosen integration events. Next, peak purity settings must be input which are specific to your method (never use the "default" values in the software, many of which are simply there as field place-holders). These include the choice of reference spectra for the peak (usually a minimum of two different Rt's are used). One reference Rt should be selected in a 'clear' zone (where no peaks are observed or detected) before the peak of interest elutes and the second reference Rt should be selected for a Rt after the peak has eluted (again, in an areas where no peaks are detected). These help to establish the baseline reference of the spectral data which will be used for the peak (poor reference choice equals invalid purity data). If you are using a gradient analysis, the accuracy of the results obtained may be of lower quality than if an isocratic analysis is used (due to the change in the spectra that occurs with the change in solvent composition over time).
In fact, as used by most, this "Peak Purity" software feature does not measure peak purity at all. Diode-Array based 'Peak Purity' determination by HPLC is a qualitative assessment of the impurity profile of the sample, not the purity.
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