The analysis of phospholipids by mass spectrometry: A comparison of field desorption (FD) and Fast Atom Bombardment (FAB) techniques.

International

Journal of Mass Spectrometry

Elsevier Scientific

THE ANALYSIS DESORPTION

Publishing

Company,

OF PHOSF'HOLIPIDS (FD) AND

ICI

D A CATLOW,

FAST

and Ion Physics,

BY MASS

ATOM

SPECTROMETRY

BOMBARDMENT

Pharmaceuticals

46 (1983)

387

387-390

- Printed in The Netherlands

Amsterdam

(F&)

Division,

: A COMPARISON

OF FIELD

TECHNIQUES.

Cheshire,

Macclesfield,

Uk.

ABSTRACT the analysis of phosphulipid mixtures is described. The use of FD and FAFJ for The results show that FD is the method of choice for such complex mixtures, providing a means of rapidly screening- phaspholipid mixtures derived from different sources for the presence of the various lipid groups and the distribution of fatty acid residues.

INTRODUCTION The

analysis

accomplished according

of complex

by chromatographic

to compound

employed

to provide

residues

present

further

and

concerning

the methods

are

phospholipid

in order was

Such

to ascertain

rapid

2) have

fatty

rarely

of screening

acid

Moreover,

commercial

species

the molecular

been

yield

in the mixture.

way

components

usually

of the

methods

present

been

the various

(Ref

the nature

levels. species

and a more

traditionally

1) separating

about

respective

has

procedures

information

the molecular

levels

(Ref

Hydrolytic

time-consuming,

samples

relative

their

mixtures

means

class.

information

their

phospholipid

present

and

sought,

EXPERIMENTAL Standards before

were

FDMS

and FABMS

FD, with

The

used

High

a cathode

for FAB was

RESULTS

Sigma

Chemical

Co and

checked

for purity

a JcoL

D300

temperature voltage

of -6kV by

generated

mass

spectrometer

activated

carbon

and accelerating

an M-Scan

Ltd

- JMA-2000

emitters

fast

(ref

voltage

atom

data 3) were

of 2kV.

system used The

for

atom

source.

AND DISCUSSION addition

compounds and

from

use by TLC.

combination.

beam

obtained

of p-toluene

has been

toa decrease

lipid

analysis

tidy1

chol-ine

ions,

there

shown

: Fig

ions

1 shows from

This

the FD mass an aqueous

at (M-H-l)+, (M+CH

OD~O-738l/S~/OOO~OOOO/$~3.00

acid

to lead

in fxagmentation.

obtained are

sulphonic

(Ref 4)

0

3

(pTSA)

to solutions

to an enhancement technique spectrum

of zwitterionic

of the

can be applied of L-c+dipalmitoyl

(M+H>+

ion

to phosphophospha-

As well as fragment methanol solution. f > (ref 5) and (M-lNa)+. After adding

1983 Elsevier Scientific PublishingCompany

388 p-TSA

there

is a marked

Figure 1

46a

Figure 2

With

mixtures

ined using the peak acid

reduction

FD Mass Spectrum

of phospholipids

this method.

Table

for egg between

1 compares bean

lecithins

as shown

infig

Choline.

150

%0

Choline

ions,

fragment

Phosphatidyl

the molecular

and soya

these

and

650

600

FD Mass Spectrum of L-a-Phosphatidyi

identities

distribution

of L-a-Dipalmitayl ---

550

500

in adduct

=%vE

Followinq Addition of p-TSA.

species

the relative lecithins.

can be readily intensities

The

is immediately

and

difference apparent.The

determLists

in fatty presence

2.

389

of each followed

TABLE

fatty

acid was

by GC-MS

of

confirmed

the

fatty

by hydrolysis acid methyl

of the

Lecithins

(Ref

esters.

L Relative

Intensities Soya

Egg Lecithin

m/z

Identities

Lecithin

473

157

14

518

34

0

520

233

55

522

68

6

734

62

31

744

96

746

C 18:2 LPE %8:3

Lpc

'LB:2

Lpc

%:l

Lpc

di 'L6:O

PC

0

di CL&L

PE

144

0

C18:O/C18:1

PE

758

500

785

c16:o/c18:2

pc

760

LOO0

177

c16:o/cL8:1

pc

762

192

14

c16:O/c18:0

PC

780

21

202

c18:2/c18:3

PC

782

123

1000

c18:2/cL8:2

PC

784

110

405

c18:2/cL8:L

pc

786

323

262

788

336

46

cL8:1/cL8:o

pc

806

199

4

'18:2/'20:4

PC

808

62

4

cL8:L/c20:4

PC

205

8

cL8:O/c20:4

PC

810

When

FAB

ionization

is observed,

fragmentation

cL8:2/L8:o

and/or

di CLgE1

PC

LPE = lyso phosphatidyl ethanolamine, LPC = lyso phosphatidyl choline, PE = phosphatidyl choline, PC = phosphatidyl ethanolamine.

Abbreviations:

ion

6)

and

for the analysis

is applied

together

with

the extensive of minor

to L-a+dipalmitoyL

considerable background

components

PC,

the expected

fragmentation severely

in Lipid

limits

mixtures,

(Fig 3).

(M+H)+ This

the use of FAB

390

Figure

3

Dipalmitoyl -- Phosphatidyl -__

Choline

by FAB MS

Acknowledgements The author wishes to thank Dr D E Games of Cardiff University for helpful discussions and ICI Pharmaceuticals Division for permission to report this work.

REFERENCES 1.

2. 3. 4. 5.

6.

J.C.

Touchstone, J.C.Chem, K.M. Beaver Lipids 1980 15(l) 61-62. M. Batley, N.H. Packer and J.W. Redmond J.Chromaogr. 1980 198 520-525. H-D. Beckey, E-Hilt and H.R. Schultcn J.Phys.E l.973 6(10)043-1044. 198L 53 25-29. T.Keough and A.J. De Stefano Anal. Chem. G .W. Wood and P-Y. Lau Biomed. Mass Spectron 1974 1. 154. G.V. Marinetti, Biochemistry 1962 1 350-353