. 2021 Feb 5;413(8):2125–2134. doi: 10.1007/s00216-021-03177-y

Table 1.

Selected cardiac glycosides from Zhang et al. [23] also assigned in wounded A. curassavica leaf by 3D-surface MALDI MS imaging. Metabolites were assigned, based on high mass accuracy of full scan MS data. In general, cardenolides were readily and mainly detected as [M + K]⁺ adduct ions in positive-ion mode

Compound	Chemical formula	Adduct	Exact mass (u)	RMSE (ppm)
Calotropagenin	C₂₃H₃₂O₆	[M + K]⁺	443.1830	0.86
Uscharidin	C₂₉H₃₈O₉	[M + K]⁺	569.2147	1.61
Calotropin/calactin	C₂₉H₄₀O₉	[M + K]⁺	571.2304	1.52
Calotoxin	C₂₉H₄₀O₁₀	[M + K]⁺	587.2253	1.27
Calactinic acid	C₂₉H₄₀O₁₁	[M + K]⁺	603.2202	1.21
Asclepin	C₃₁H₄₂O₁₀	[M + K]⁺	613.2410	1.29
Uscharin	C₃₁H₄₁NO₈S	[M + K]⁺	626.2184	1.15
16α-Acetoxycalotropin	C₃₁H₄₂O₁₁	[M + K]⁺	629.2359	1.23