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. 2011 May;52(5):1039–1054. doi: 10.1194/jlr.D013987

Fig. 2.

Fig. 2.

Mass spectra of sterol lipids without fragmentation. Sterol lipids were directly infused into the Q-TOF mass spectrometer via nanospray ionization. Ion spectra were recorded in the positive mode without fragmentation. A: Free sterols from Arabidopsis leaves after SPE purification and derivatization as betainylchloride esters. Cholestanol and stigmastanol were used as internal standards. B: Sterol esters from Arabidopsis leaves after two-step SPE purification. The following internal standards were included: 16:0-cholesterol, 16:1-cholesterol, 18:0-cholesterol, and 18:1-cholesterol. C: Sterol glucosides (soybean); internal standards were cholestanol-Glc and stigmastanol-Glc. D: Acylated sterol glucosides (soybean); 16:0-Glc-stigmastanol, 18:0-Glc-stigmastanol, 16:0-Glc-campestanol, and 18:0-Glc-campestanol were the internal standards.