Figure 9.

(a) LC-MS/MS chromatogram of standard CTX solutions showing that the [M + Na]⁺ and [M + NH₄]⁺ ions were favored for P-CTX1B (P-CTX-1), while the [M + NH₄]⁺ and [M+H]⁺ ions were dominant with similar intensities for P-CTX3C (P-CTX-3C) at identical conditions. A linear gradient of water-methanol solvent mixture, containing ammonium formate and formic acid, was used for chromatographic separation. SIM was performed in positive mode for ions at m/z [M + Na]⁺, [M + H]⁺ and [M+NH₄]⁺. Reproduced with permission from ref. [130]; (b) LC-MS/MS chromatogram and retention time of P-CTXs standards using a Zorbax C18 column, water and methanol as eluents, and a linear gradient. The separation of various CTX congeners is shown. Reproduced with permission from [130]. Copyright Elsevier Ltd., 2018; (c) LC-HRMS high resolution mass spectra of CTX1B (P-CTX-1) obtained from CTX standard, showing adduct peaks and isotopic patterns, reproduced with permission from [132]. Copyright Elsevier Ltd., 2017.