Hello! Is it possible to identify pigments using HPLC-MS but without the use of any standards? Despite not having any pigments standards, I have performed the separation of my extracted pigments sample in HPLC-MS. I tried comparing my results with those of other studies who have used standards but I still couldn't identify which pigments I have.
Thank you in advance.
No. "MS" data is only as good as the overall method used to collect and evaluate it (The "method" includes the column, mobile phase, instrument settings, standards and proof that the method follows good chromatography fundamentals). With no standards for comparison and other orthogonal techniques used, no positive identification would be possible, only qualitative. Purely speculative.
MS data on its own has very little value as a MS system will always output "data". Data "from other studies" would be anecdotal at best as only data collected on the same instrument, by a trained operator (which takes many, many years) using standards with an approved method would be useful to draw conclusions from.
Although the use of standards is a common practice for pigment identification, HPLC-MS can still be a valuable tool for the qualitative identification of pigments in the absence of standards.
Several studies have demonstrated the identification of pigments through HPLC-MS analysis, even in the absence of standards .
you can find some articles:
1-Aparicio-Ruiz, R., Riedl, K. M., & Schwartz, S. J. (2011). Identification and quantification of metallo–chlorophyll complexes in bright green table olives by high-performance liquid chromatrography–mass spectrometry quadrupole/time-of-flight. Journal of agricultural and food chemistry, 59(20), 11100-11108.
2-Reiß, L., Machill, S., Lübken, T., & Herm, C. (2023). HPLC–HR-ESI–MS/MS identification of fluorescent dyes and optical brighteners and their degradation products in daylight fluorescent paints. Heritage Science, 11(1), 146.
3-Zhang, J., Liu, D., Cao, P., Wang, Y., Keesing, J. K., Li, J., & Chen, L. (2016). A highly sensitive method for analyzing marker phytoplankton pigments: Ultra‐high‐performance liquid chromatography‐tandem triple quadrupole mass spectrometry. Limnology and Oceanography: Methods, 14(10), 623-636.
William Letter Indeed. Trying to compare my results with data from other studies seemed like a difficult task as I couldn't find "similarities", therefore I couldn't identify any of the pigments I have. Almost nothing "matched"; which only makes more sense after reading your explanation. Since I can't afford the standards, neither find a lab that has it, I have tried to find any other way without its use. Thank you so much for your answer, it was very helpful.
Abdelhak Maghchiche Thank you for your answer, but unfortunately all the articles you have mentioned above used standards in their work:
1- Materials and methods: chemicals and standards section
2- HPLC–HR‑MS/MS section
3- Material and procedures: Chemicals and reagents section
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