Fragmentation Mechanism of Alkylmonoglycosides by Mass Spectrometry

8/9/2019 Fragmentation Mechanism of Alkylmonoglycosides by Mass Spectrometry

1/5

ANALYSIS

e N.

A.

Soyed,M. EL

Sukkory,A.

Aiod ond

W. El-Azab

Fragmentat ion

echanism

f Alkyl-

monoglycosidesy Mass pectrometry

Alkylmonoglycosides

ith

different

alkyl

chain engths

ApCa,

APCe, PCro

nd APGr4)

ere

prepared

y

Fisher eaction

of

glucose

ith

fattyalcohols.

xcess

lcohol

was used o increase

the

possibility

of

producing

alkyl monoglycosides roducts.

Mass

spectrometry

ith

chemical

onization

was used o

con-

firm their

structures

s

alkyl monoglycosides.

ccordingly.he

obtained

signals

t m/z:293.,

ZO7,

21 and

277 corresponds

to their protonated

olecules.

he

base ines

which

are the

most ntensive

ignals

n each

pectrum

t m/z:145, 127,

41

and

197

epresenthe mostabundantonsand define he path-

way of their

ragmentation

echanism.

he

mass145

or APCg

is

generated

rom

the

parent

on

by elimination

f the

mass

ROH ollowed

by

H2O.For

his

compound

cleavage

ccursat

the

C-O bond next

o the

glucose

ing,

while ragmentation

f

alkylmonoglycosides

ith carbon

umber

, l0 and 14

occurs

at the O-R

bond releasing

he

alkyl

cationR of the

aglucone

moiety

CnHrn*1)

long

with large

ragment

ons characteristic

of

the

glucose

moiety.

Keywords:

Surfactant,

lkyl

polyglycosides,

ass pectrometry,

aglucone

Fragmentierungsmechanismus

on

Alkylpolyglycosiden

it -

tels Massenspektrometrie.

lkylmonoglycoside

it unter-

schiedlichangen

Alkylketten APG',

APce,

ApGro

und ApGla)

wurden

aus

Glucose nd Fettalkoholen

ittels Fischer-Reak-

tion hergestellt.

er

Alkohohiberschuss

urde zur

Steigerung

der

Ausbeute

n Alkylmonoglycosid-P rodukt

enutzt.

ur

Absi-

cherung er Molekrilstrukturen

er Alkylmonoglycoside

urde

die Massenspektrometrie

it chemischer

onisation

ingesetzt.

Dieerhaltenen

erhdltnisse

on Molekiilmasse

u onenladung

m/z:293,3O7,321

und 377

entsprechen

enen

der

proto-

niertenMolektile.

ie

Basislinien,

ie in

jedem

Spektrum ie

stdrksten

ignale ei

m/z:145,

127,4t

und 197

sind, eprd-

sentieren

ie am hiiufigsten

orhandenen

onen und

bestim-

men den Pfad hresFragmentierungsmechanismus.rirApGs

wurde

riber

die Abspaltung

es

Alkohols

ROH und

an -

schlieBendon

H2O

aus dem Ausgangsmolek0l

ine Masse

von 145

berechnet.

i.ir iese

Verbindung

rfolgt

die Spaltung

an der

C-O Bindung,

ie

dem Glucosering

m niichsten

st ,

wiihrend

die Fragmentierung

er Alkylmonoglukoside

it 9,

l0 und t4

Kohlenstoffatomen

n der

C-R-Bindung

tattfindet.

Dabeiwird

ein Alkylkation

R des Agluconrests

CnH2n*1)

in-

hergehend

mit

groBen,

i.irden

Glukoserest

harakteristischen

lonenfragmenten

bgekist.

Stichwiirter:

Tensid, lkyl

olyglycoside,

assensprektrometrie,

Aglucon

1 Introduction

Nowadays

allcylmonoglycosides

s nonionic

surfactants are

not obscure.

They

are

produced

rom

renewable aw

materi

als namely

starch and fat

or their

derivatives

according to

their

proper

application

at industrial

scale.The

use

ofglyco-

sidases o

catalyze he

synthesis

of alkyl glycosides

has

at-

tracted

considerable nterest

since alkylglycosides

re

biode-

gradable

onionic

and nontoxic

surfactants

1-31.

Analysis

is an

essential equirement

for

determining

their composition

and

structure.

So, mass spectrometry

with

its

differentmethods

such as electron

mpact.

chemicai oni-

zation,

field

and spark

ionization is

an important

tool for

identification and structural determination of alg polyglyco-

sides and their

derivatives.

Sugar

linkage position

in glycosides

was determined

using

ammonia

chemical ionization

mass

spectrometry

at

1ow gas pressure.

The

obtained

mass

spectrum gave nfor-

mation

from

both EI

as well as

CI mass spectrometry

n

one step

l4].

Determination

of

APGs

as their

trimethylsilyle

ethers was performed

by Billian

and Stan. The

substance

can be identified

by

characteristic

mass spectra

fragments

such as rnlz

204

and 217 which

are the

base

peaks

of

pyra-

nosidesand

furanosides.

The length

ofthe

alkyl chain

could

be identified

n homologous

mass

series

[5].

On the other

hand,

acetylated

B-D-glycopyranosides

were

characterized

by GC-MS

ahalysis

of the prepared

tetra

acetyl glycosides.

It was found that the resultant fragment ion characteristic

of the aglucone

moiety

was

present

in all mass

specrra,

along with

the fragments

obtained

from acetylated

glucose

[6].

Also, alkylglycosides

ad

been

studied by

electrospray o-

nization

mass

spectrometry

the

effect of the hydrophobic

and hydrophilic parts

of these

compounds

on the stability

of (M + Na)* ions

had

been evaluated

[7].

The

a and

B

epi

mers

and ring

isomers (pyranosides

and furanosides)

of

allgl monoglycosides

were resolved

using the

alkyl amide

column and isocratic

elution

I8l.

And,

the

characteristic

mass fragments

of di and tri

saicharides

obtained

by trans-

galactosylation

reaction

had

been

acquired using

GC-MS

spectrometry

[9].

Also, fragmentation

of D-glucose

and alkyl-

monoglycosides

n the presence

of sodium ions in

an ion-

trap spectrometer as studiedby Beneito-Cambrat al. [10].

Therefore,

the aim

of our study

was to determine

the

molecular

masses

of the prepared

compounds

as alkyl

monoglycosides

roducts

APGs,

APGe,APGIS

and APGIa)

and define the pathway

of

their fragmentation

mechanism.

2 ExperimentalTechniques

In

our

previous

article

[11],

the

synthesis of octyl, nonyl,

decyl and tetradecyl

glycosides

was performed

through

transglycosidationprocess

using p-toluene

sulfonic

acid as

a catalyst

12-15].

The purity

of the

products

was determined

by using HPLC

with refractive

ndex

detector.The

structure

of the

prepared

compoundswas confirmedby FTIR,1H NMR and ttc NMR.

Also

the molecular

mass was

confirmed

by using mass spec-

trometry.

In

the

present

paper

detailed

mass spectrometry

studies

of the synthesized

allcylglycosides

ere

performed.

For this

217

W

/

Tenside

urf .Det.47

(2O1O)

@

Carl

Hanser

Publ isher,

unich


2/5

NaglaA.

Sayed t a l . :

Fragmentat ion

echanism f a lkylmonoglycosidesy massspectrometry

purpose_the

SSQ

7000

mass spectrometer rom Finnigan

was useo.

Analysis

of

the

allglglycosides was

performed

by direct

insertion probe

using

chemical

ionization technique with

methane

as

reagent gas. MS

condition:

ionization

voltage

70eV,

temperature 100'C increasedat lO0'C/minute to

350'C, mass angewas 50-6700 massunits.

aQ o

g9

40

2Q

P+ 6g

a"Pi

5B

F

APG8

-

6

lllt

L9

E6q

E

au o

eo

66

ao

BO

APG

9

E+ OE

*.

+5

4E

.2

4a

.3 4rH.* l

FFT

-

n,

49 6

EO

60

{0

=o

E+ eg

4.63

-4 .4-ZiL-5 +.z_e.-€

APG 0

-? 5€F-e

ro 6

5A

ao

=o

Figure Massspectra f the

prepared

PCs

218

E+

0g

il

.4 #

TensideSurf.

Det. 47

(2O1O)


3/5

Nagla

A' Sayed

t

al . :Fragmentat ion

echanism

f

alkylmonoglycosides

y mass

pectrometry

3 Results

nd

Discussion

Alkylmonoglycosides

with

different

hydrocarbon

chain

Iengths

(APGs,

APGe,

APG16

and

ApGla)

were

character-

ized^by

MS

analysis.

he

mass

spectra

of

such

compounds

confirm

their

structures,

and the

obtained

signals

sfred igtrt

on the mechanism of their fragmentation palhway.

In general,

glucose

s

a

common

factor

in the prepared

compounds.

As it

can

be

seen rom

Fig.

1, the

expected

mo-

lecular

ion

peak

of glucose

was not

recbrded,

moit probably

due to

the

low

volatility

of glucose

which has

seveial

polai

groups

1161.

(a)

Mass

spectrum

of APGg

was compatible

with its

structur-

al formula.

The

molecular

on

peak

at

mlz=293

corye-

sponds

o protonated

molecules

bf octylmonoglycoside.

o

The

tallest

ine

alrnf

z: 145

s its

basepeik.

It repre-

sents

he most

comment

fragment

ion to

be formed.

o

The

second

fragmentation

mechanism

can

be seen

from

scheme

2

and

3, APGe

and Apclo

have

very

sim-

ilar

fragmentation

pathway

which

takes place

by elim-

ination

of one

molecule

of water

mlz:18

and four

protons

o generate

he positive

ons

at mlz=285

and

mlz:299,

followed

by

elimination

of

C,H2,

and oxy-

genmolecule o give he ions at mlz: 127.Moreover,

-mlz:85

may

arise

by

cleavage

f the

glycosidic

ing.

(c)

Molecular

on peak

atmlz

=

377

epresent

he

massof

pio-

tonated

molecule

of tetradecyl

monoglycoside

ApG1a).

he

basepeak

occurs

at mlz

=

I97

corresponds

o its

alkyl ion.

o

Fragment

ons

witll

large

massei

characteristic

f the

glucose

moiety

are nf

z

=

31,3, 85

and 2I3

generated

by elimination

of

[(CH2)3,

HzO),

2Hr],

27H2

and

C5H12 espectively.

Basically,

t

has the

same

frag-

mentation

mechanism

asApGe

and ApGro,

but

with

slight

difference

of its fragmentation

steps

as shown

in

scheme

4.

empa

)-

' f

e

st

m

ate r ia

ls

This

value

defines

ts frag-

mentation

pathway

which

occurs at the C-O bond

next

to glucose

ring,

and

the positive

charge

tend

to

stay with

the

ring

frag-

ment

{scheme

1).

o

The

intensive

sienal

at the

mass

mfz:163

is

gener-

ated

by

elimination

of the

ROH

molecule

from

the

parent

ons

ollowed

by suc-

cessive

elease

of

a warer

molecule

o

give

he

masses

mlz

:

1,45

nd

mlz

=

127

Fragment

on

CaH5O2

at

mlz:85 originates ro m

cleavage

of

the glycosidic

nng.

Other

signals

present

in

the

spectrum

may

be gen-

erated

from

alkyldiglyco-

side

and impurities

since

the purity

of

the prepared

APG8

compound

was

around

92%lL7l.

Mass

spectra

of

APGe

and

APGI6

are shown

n

Fig.

1. It

is

apparent

that

the

signal

peaks

at mlz=307

and ml

z:321

representshe parent

ions

which

confirm

their

structures

mainly

as

nonyl-

monoglycoside

and

decylmo-

noglycoside.

Two

fragmenta-

tion

mechanisms

can

be

found

for

APGe

and

APG16.

o

The

observed

ase

ines

at

mlz=127

for

ApGe

and

mlz:

t41for

APG16

epre-

sents

the alkyl

chains lost

in

fragmentation.

The

re-

sults

obtained

define

the

main

pathway

of

their

fragmentation

mechanism

which provides

strong

sup-

port

ofthe

fact

hat

cleavage

occurs

at

the

O-R

bond

with

charge

on alkyl

on.

Test

materials

(b)

for

assessing

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4/5

NaglaA.

Sayed t a l . :Fragmentat ion echanism

f

alkylmonoglycosidesy mass

spectrometry

QH2OH

ffi

/2163

l *"

I

fi"J

^

T,Z'x

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OH

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NaglaA.

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echanism

f

alkylmonoglycosides

y mass

spectrometry

References

1. Kren,

V andThiem,

.:Chem.

Soc.Rev.26

1991)

63-473

2. VonRontvvijk,

.,Woudenberg-Von

osterom,M.

andSheldon,R ,4.;J.Mol.

Catal . .Enzym

(1999)

ll

-552.

3. Lindhorsl

K: Essentials

f carbohydrate

hemistrynd biochemistry

iley-

VCH,New

York. 000.

Figure2

Cleavage f the

C-O bond

or APC'

and he O-R bond for

the

APCe, PCro

ndAPCIa

o

Beyond

he

base ine,

other intensive

signals

CoHz.*r

(mlz:

I41,

t27)

and C.H2a_1

mlz:11L,97

and 83)

originate

from

the

aglucone

part

by successive e-

Iease

of methylene

group.

A general

concept can

be deducted

from

the obtained re-

sults.

The

probability

of cleavage

f a

particular

bond is re-

lated to the

bond

strength. Accordingly,

the diflerence

be-

tween the

mechanism

of fragmentation

pathway

for APG3

and that of APGe,APGI6 and APGIa may be attributed o

the inductive

eflect of the

methyt group.

It is

well known

that the

inductive

effect

of methyl group

increases

he elec-

tron density

on oxygen

atom

and thus

strengthen the

O-R

bond and hinders

the

breaking

of the

O-R bond.

Conse-

quently,

for

APG3

cleavage

ccurs between

he oxygen

arom

and the glycosidic

carbon

atom forming

the intensive

signal

at the mass

mlz:

163.On

the other

hand,

as he alkyl chain

increases

beyond

Cs, the inductive

eflect of the methyl

group

dies out (since

t is

significant

only over

a short dis-

tance)

and the induced

energy

can overcome

he O-R

bond

strength releasing

he

all1yl ragments

ions (mlz

=

I27, t4L

and 1,97, igure

2) .

4 Conclusion

A series

of alkylmonoglycosides

with alkyl

chain

lengths

(8,

9,

10

and 14)

were

synthesized

using transglycosidation

method.

Characterization

of these

compounds

-was

per-

formed

by MS analysis.

t

was observed

hat fragmentation

pathway

of

octyl monoglycoside

occursat the

C-O bond next

to the glucose

ring,

while for APGe,

APGI6

and ApG14,

cleavage

ccurs at the

O-R

bond.

Reznicek,

. andMotho,

M.: Carbohydrates

esearch

93

(1996)

t3j- t3Z

Billion,P..andSton,H.J.: Tenside, urf.Det.35(3) (199S) 8t - i84.

Jerkovic, and

Mostelic, .:

Croat.Chem. Acta77(3)

(2OO4)

529-535.

Zembrzusko, .,

Zgolo-Crzeskowio(

A. and Fronsko,

M.: Tenside,

Surf. Det.

42(4)

(2005)

226-228.

Beneito-Combro,

M., Bernobe-Zofon,

V.,Herrero-A,4ortinez,

. M.

and Romis-

Romos,

.'.Talanta4

(2007)

65-it.

Cordelle-Cobos,

, Maiinez-Villoluengo,

C.,Sonz,M. L.

andMontillo, A.:Food

Chemistry 14

2009)

1099- 1105.

Beneito-Combro,

M., Bernobe-Zofon,

V, Herrero-Mortinez,

. M.

and Romis-

Romo9G.:Analytical

etIeB 2 (2009)

907-921.

El-Sukkary,M.

M.

A.,

Soyed,

N. A., smoil, A.

and El-Azob,W L

M: J. Surt.

Deterg./

QOOS)

29-131.

Hill, K.

andRhode,

O: Fett/Lipid 0t

(1999)

25-33.

Sowodo, .:

1990)

pn

Pa[.02,264,789

1990)

CA

t24950b,

l4 .

Cruexke,

. and

Schmidt, .:

(1996)

Cer Offen DE 4, 431,

953.

Cruezke,

. and

Schmtdt, .

(

996)

Cer Offen DL 4, 44,

Og9.

Silverstein, .M, Torrill,

T.

C. andBossler,

:

Spectroscopicdentification

f

Organic ompounds;

'n ohn

Wiley& Sons,New

York.

Woleed l-Azob:

Sc. hesis,

etroleum esearch

nstitute,00i.

4.

5 .

6 .

7.

8.

9.

10 .

| .

12.

I3 .

t4 .

15 .

16 .

11.

Received:

9.12.2009

Revised:

6.02.2010

*

Conespondence

to

Dr.Nagla

Sayed li

Egyptian

etroleumResearch

nstitute

Near eevan

Evaluation

ndAnalysis

Nasr

City

Caio,11727

EgYPt

[email protected]

The

authors

f this

paper

Mohommed

El-Sukkorys

Professor

f OrganicChemistry

t the Petrochemical

e-

panmenl.

AsmoilAiod

is Professor

f Organic

Chemistry t Petrochemical

epartment.

WoleedEl-Azob

s a researcher

n Organic

Chemistry t the

Evaluation nd Analysis

department.

You

will find the

article

and additional material

by

enter-

ing the document

number

T5110069

on our website

at

www.tsdjoumal.com

Tenside

urf .Det.

47

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221

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Documents

Fragmentation Mechanism of Alkylmonoglycosides by Mass Spectrometry