43
Figure 3 – Simple Data Review Display
When two peaks co-elute, one peak of the co-eluted peak pair will be “hidden” in the UV chromatogram. Standard UV results data such as Retention Time and Resolution will be missing for this peak for all experiment runs in which the peaks co-elute. This negatively impacts prediction models derived from the method development experiment results. Using PDA and MS spectral data to automatically locate “hidden” peaks and fill in missing results data can dramatically improve the quality of prediction models.
• Two or more peaks with identical mass data. There are many circumstances in which two peaks will have the same parent mass value, and therefore the same mass-to-charge ratio (m/z). A solution in these cases would be to use a mass spectrometer capable of fragmenting all ionizable compounds coupled with a spectral library for identification. However, this capability is unavailable in many labs charged with developing LC methods. Utilizing an economical mass detector, and coupling it with automated diagnostics utilizing UV spectral data and standard peak results data provides a unique solution to this problem.
• Non-absorbing and non-ionizing compounds.
In most cases it is desirable to have a mass spectrometer compatible LC
method which resolves all sample compounds. This goal is complicated when the sample contains compounds which either do not absorb, as shown in Figure 1 (no UV data), or do not ionize, as shown in Figure 2 (no MS data). These cases require coupling the PDA and MS spectral data into the automated peak tracking protocol. This enables creating a merged chromatogram which contains all of the peaks and the associated results data needed for data modeling.
PeakTracker also incorporates the additional features and functions needed to complete the tracking workflow. These include (1) a paired graphical and numerical display of the MS and PDA spectra data for each peak, as shown in Figures 1 and 2, respectively, along with facilitation tools for manual manipulations to tracking results, and (2) a stacked display of the the UV chromatogram and Total Ion Chromatogram (TIC) for each experiment run for simple visual comparisons and tracking confirmation. In addition, as shown in Figure 3, PeakTracker displays a user-filterable table of the UV peak results with highlight colors to easily identify tracking updates to peak data – for example, updates to missing data for co-eluted peaks and added data for non-absorbing peaks merged into the UV chromatogram. Once tracking is complete, PeakTracker automatically maps compound
names to all of UV results data computed by the CDS for all identified peaks in the experiment chromatograms for automated modeling and visualization. Automated peak tracking which fully utilizes PDA and MS data within a chromatography data framework greatly simplifies the integration of MS data into the method development workflow. Further, the ability to incorporate non-absorbing peaks into UV experiment chromatograms directly supports the development of MS compatible HPLC methods, which can be of great benefit to both production and quality control.
References
[1]R. Verseput, J. Turpin, Chromatography Today, August / September 2015, 64
[2]A. Schmidt, C. Wess, Journal of Liquid Chromatography & Related Technologies, 37 (2014) 18
[3]B. Debrus, D. Guillarme, S. Rudaz, Journal of Pharmaceutical and Biomedical Analysis, 84 (2013) 215– 223.
[4]J. Kaufman, D. Mans, FDA-DPA, Presentation to the CASSS CMC Strategy Forum Europe 2015
[5]J. Strasters, H. Billiet, L. Galan, B. Vandeginste, Journal of Chromatography A, Volume 499, 19 January 1990, Pages 499-522
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