Basic principles and terms

• PDA View: PDA views are the different ways of displaying the acquired PDA data in the customizable PDA Chromatogram window. Up to four views can be displayed at one time; any combination from the following views may be selected: Isoplot, Chromatogram, Spectral, 3D, Peak Purity, Peak Purity Spectra, Spectral Library, and Spectral Search. The user can easily extract chromatographic signals from PDA data to determine the optimal detection wavelength for each peak.
• PDA Method: The Clarity PDA method includes an option for Spectral Library Search and Peak Purity Analysis.
• Spectral Library: Clarity can compare the peak spectra with the spectra of an unlimited number of spectral libraries. Spectra stored in a Spectral Library include retention times and analysis parameters (optional). The Spectral Library Search can perform automatic identification of integrated/calibrated components (peaks). The library search may be constrained by the retention time and wavelength ranges. To determine the match with a library spectrum, a match factor is calculated based on either the Least Square, Weighted Least Square, or Correlation methods. A Background Correction option is also available. The particular formulas and calculation details can be found in the chapter "Appendix - Mathematical Formulas".
• Peak Purity: This analysis helps to discover hidden impurities. It is applied to all integrated/calibrated peaks in the active signal, and is calculated either based on five significant peak points or all spectral point within the peak. A similarity curve is then displayed in the PDA Chromatogram window. Peak Purity analysis can be optimized by setting custom preferences relating to wavelength restriction and absorbance threshold. The calculation details can be found in the chapter "Appendix - Mathematical Formulas".