Page 11 - Shimadzu LCMS-IT-TOF

Examples Highlighting the Neutral Loss Survey Function

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The combination of the neutral loss survey and MS measurement provides accurate mass information that can lead to highly reliable struc-
tural analyses of phospholipids.

1
MS measurement
phospholipid
2
MS measurement :
CH2-O-PO (OH) -O-X
Polar radical-specific neutral loss (NL) Polar radical information
CH -O-CO-R2
3
MS measurement : Lipid chain information
CH2-O-CO-R1

Setting PS (Polar radical X : serine) - specific NL (87 Da) and performing the neutral loss survey

MS 1 PC : Phosphatidilcholine
PS : Phosphatidilserine
[M-H] - for diacyl 40:5 PS 810.5225 PA : Phosphatidic acid
834.5237
Expected 836.5442 FA : Fatty acid
PS or PC?
[M+CH3COO] - for diacyl 36:6 PC 836.5431 O loss of 87.0320 Da
Expected 836.5442 -1.31 ppm PA-H : C2H2 (NH2)COOH
R1 O O
P COOH
O O
O -
100 200 300 400 500 600 700 800 900 m/z R2 O NH2
O
NL of 87 Da Detection of PS-specific NL: Polar radical information
MS 2 of m/z 836.5
Performing MS 3 measurement of precursor ions
[M-H] - for diacyl 40:5 PA
at m/z 749 by neutral loss survey
Expected 749.5121
749.5150
-3.87 ppm
O
1-lysoPA--H 1-cyclicPA--H
+H -H2O
R1 O O
100 200 300 400 500 600 700 800 900 m/z FA--H P
FA--H O OH
O -
O
R2
+H -H2O
2-lysoPA--H 2-cyclicPA--H
O
MS 3 of m/z 749.5
MS 3 measurement: Lipid chain information
[M-H] - for acyl 18:0 FA
283.2636 Expected 283.2637
- 0.35 ppm 419.2550
- 3.10 ppm [M-H] - for acyl 18:0 cyclicPA
Expected 419.2563 Sample : lipid mixture from rat liver
Column : Si column (1.0 × 10 mm)
100 200 300 400 500 600 700 800 900 m/z Mobile phase : gradient of acetonitrile (A)
and methanol (B)
Using neutral loss survey, diacyl 18:0 – 22:5 PCs in the lipid mixture were easily identi- (including 0.3 % formic
1
3
fied. Mass accuracy of less than 5 ppm was obtained in MS through MS using an ex- acid and 0.1 % ammonia
ternal standard. water in (A) and (B) each)
LCMS-IT-TOF
Liquid Chromatograph Mass Spectrometer 11