. 2024 Jul 27;22(8):343. doi: 10.3390/md22080343

Table 3.

Pigment identification in the Skeletonema marinoi ethanol extract was conducted considering polarity and high-resolution mass spectrometric data. Mass differences (ppm) were compared between theoretical exact and measured masses. It should be noted that retention times (Rt) varied between RP-HPLC and UPLC-HRMS analyses. “Max. Abs” refers to maximal absorption wavelengths. Absorption spectra, maximal absorption wavelengths, band III/II ratios for carotenoids, Sorets for porphyrins were also considered to confirm the pigment identification.

Molecule	Formula	Ion	Theoretical Monoisotopic Mass (m/z)	Peak Area (×10⁶)	RT (min)	Score (%)	Experimental Monoisotopic Mass (m/z)	Error (ppm)
Pheophorbide a	C₃₅H₃₇O₅N₄	[M + H]⁺	593.2758	303	11.18	98.5	593.2775	2.79
		[M + K]⁺	631.2312				631.2343	4.91
		[M + Na]⁺	615.2578				615.2579	0.16
Pheophorbide a isomer	C₃₅H₃₇O₅N₄	[M + H]⁺	593.2758	127	11.43	97.3	593.2760	0.26
		[M + K]⁺	631.2312				631.2292	−3.17
		[M + Na]⁺	615.2578				ND
all-trans-Fucoxanthin	C₄₂H₅₈O₆	[M + H]⁺	659.4306	184	10.88	97.6	659.4307	0.13
		[M + H − H₂O]⁺	641.4201				641.4201	0.08
		[M + Na]⁺	681.4126				681.4134	1.23
cis-Fucoxanthin	C₄₂H₅₈O₆	[M + H]⁺	659.4306	359	11.52	95.8	659.4324	2.71
		[M + H − H₂O]⁺	641.4201				641.4184	−2.57
		[M + Na]⁺	681.4126				681.4147	3.14
13-OH pheophorbide a	C₃₅H₃₆N₄O₆	[M + H]⁺	609.2708	465	11.01	99.4	609.2709	0.16
		[M + K]⁺	647.2266				647.2386	18.54
		[M + Na]+	631.2527				631.2530	0.48