. Author manuscript; available in PMC: 2019 Dec 11.

Published in final edited form as: Anal Chim Acta. 2018 Mar 9;1037:256–264. doi: 10.1016/j.aca.2018.02.051

Table 2.

Assignment of exosomal lipids that distinguish normal from early or late stage NSCLC using RF and LASSO.

MF¹	adduct	accurate mass²	lipid assignment³	RF	LASSO

C44H82N1O8P1	[M+H]⁺	784.58508	PC(18:1_18:2)	Yes	Yes
C44H84N1O8P1	[M+H]⁺	786.60073	PC(18:0_18:2)	Yes	No
C46H80N1O8P1	[M+H]⁺	806.56943	PC(16:0_22:6)	Yes	No
C42H80N1O8P1	[M+H]⁺	758.56943	PC(16:0_18:2)	Yes	No
C39H79N2O6P1	[M+H]⁺	703.57485	SM(d18:1_16:0)	Yes	No
C46H86N1O8P1	[M+H]⁺	812.61638	PC(18:0_20:3)	Yes	Yes
C44H80N1O8P1	[M+H]⁺	782.56943	PC(16:0_20:4)	Yes	No
C46H82N1O8P1	[M+H]⁺	808.58508	PC(16:0_22:5)	Yes	No
C47H76O2	[M+Na]⁺	695.57375	CE(20:4)	Yes	No
C55H98O6	[M+Na]⁺	877.72556	TAG(52:5)	Yes	No
C47H93N2O6P1	[M+H]⁺	813.68440	SM(d18:1_24:1)	Yes	No
C44H86N1O8P1	[M+H]⁺	788.61638	PC(18:0_18:1)	Yes	No
C40H80N1O8P1	[M+H]⁺	734.56943	PC(16:0_16:0)	Yes	No
C57H100O6	[M+Na]⁺	903.74121	TAG(54:6)	Yes	Yes
C24H50N1O7P1	[M+H]⁺	496.33977	LysoPC(16:0)	Yes	No
C20H42N1O6P1	[M+H]⁺	424.28225	LysoPC-pmg(12:0)⁴	Yes	No

Molecular formula

estimated mass error <±0.1 ppm. These lipid features (as defined in the text) were verified by further MS1 analysis as described in the Methods, except that the resolving power was set to 500,000 at m/z=200.

In this study lipid features (monoisotopic accurate m/z values) were used for classification. The molecular formulae and lipid name assignments are interpretations listed for the reader. The assignments were based on accurate mass and MS2 fragmentation patterns. CE, cholesterol esters; TAG, triacylglyceride; LysoPC-pmg, lysophosphatidylcholine-plasmalogen; PC phosphatidyl choline; SM sphingomyelin. Nomenclature according to [60,61].

⁴

This molecular formula and lipid assignment was the closest from our comprehensive lipids database. Among non-lipids there is the possibility of the non-phosphate ³¹P-containing compound C19H37N8O1P1, which is inconsistent with the phosphocholine fragment in the MS2 data (Fig. S2).