Hey José,

I think there is no online library available for carotenoids, especially for the Z isomers. In our lab we use the Carotenoids handbook (by George Britton), review articles and comparison with the All-trans isomer spectra (considering bathochromic effect and cis peak). Old school.

Best regards,

Hello, I am currently working with a series of Bixin isomers and I have files with their spectra that could be of help. Regards

Collected UV/VIS Spectra from an HPLC analysis run are not applicable for any type of "Library Comparisons". This is fundamental to the technique of HPLC and these types of comparisons do not apply to HPLC-DAD spectra unless they are from the same analysis run. No HPLC spectra libraries are available or published for this reason (unlike NMR, FTIR, EI MSD etc). The UV/VIS spectra obtained from any HPLC analysis will vary from instrument to instrument and method to method. They are not comparable separately, however you can learn some basic information from the data obtained (e.g. A general idea of what the spectra looks like when the sample is dissolved in a specific solution, or the mobile phase in this example). Because HPLC methods are fully customized to each instrument, the data collected for a sample will vary and can only be compared to data obtained on the same instrument using the same analysis method and settings. Different tubing dimensions, column type and dimensions, flow cell dimensions (volume and path-length), sampling rate, detection settings (wavelength/bandwidth), mobile phase composition, flow rate, temperature etc. all change the data.

In your example, if you wanted to know what the various UV/VIS spectra looked like for various versions of the same compound (i.e. isomers), then you could start by developing an HPLC method of analysis for all forms OR obtain pure standards. If you develop a valid method which retains and resolves the forms apart using good chromatography principles, then you could view each sample's spectra and compare them directly. Alternatively, if you can obtain pure standards of each compound, then you could dissolve them in the mobile phase and analyze each one separately using a UV/VIS spectrophotometer to obtain and store their spectra for comparison (If you acquire standards of each, you could also use these standards with a full HPLC analysis method to compare and qualitatively identify them too).