Evaluation of chromatographic columns for the analysis of PSP toxins after pre-column oxidation

We have checked 20 columns with different phases and characteristics in order to choose the best column to be used in a monitoring system. The columns with C18 phases modified to extend the pH range (Poroshell HPH, GeminiNX,... [ view full abstract ]

We have checked 20 columns with different phases and characteristics in order to choose the best column to be used in a monitoring system. The columns with C18 phases modified to extend the pH range (Poroshell HPH, GeminiNX, Kinetex EVO), those with C8 (Halo) or C12 (synergi MaxRP) phases and a C18 monolithic column (Chromolith performance) were unable to retain the toxin oxidation products sufficiently and cannot be used for this kind of analysis. Most columns with “standard” C18 phases and large particle size (4-5µm) showed good separations (Supelcosil LC18, Luna, Poroshell EC18, Kinetex), while in those with smaller particles the separation was worse.  The fused core columns allowed reducing substantially the run time. Most C18 columns for aqueous phases (Atlantis T3, Zorbax BonusRP, Ascentis Expres RP Amide) showed good retention.  Notwithstanding, some of them were unable to sufficiently separate two peaks (Zorbax, Ascentis), pointing to the Waters Atlantis T3 as the best alternative.  A biphenyl column was also tested but its separation was poor. Fine tuning the chromatography with the Atlantis T3 5µm, allowed running a complete chromatogram in 6 min. Finally a solid core column with the same chemistry than the Atlantis T3, the Cortecs T3, was tested. After some tuning of the conditions with a 75x3mm 2.5µm column it was possible to run a complete chromatogram with good separation in 2.5 min with a backpressure of 580 bar and in 4 min with 310 bar.