desorption ionization analysis of nano film products for ... film... · desorption ionization...
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OverviewTwo NanoFilm Products (NFPs) were analysed using two different desorption ionization techniques, Nano Assisted Laser Desoption Ionization (NALDI) and Tranmission Mode Desorption Electrospray Ionization (TM-DESI). Both methods worked well and the NFPs were found to contain hydrolysates and condensates of organo-functionalised silanes.
Above:Silanes and siloxanes in NFP 1 (floor coating).Below: Silanes and siloxanes in NFP 2 (tile coating)
NALDINALDI is a new type of ionization technique for MALDI-type instruments comprising targets of inorganic nano structures coated with a hydrophobic, organic layer that facilitates sample deposition and Laser Desorption Ionization (LDI) performance (1). They absorb laser energy causing LDI without need for a matrix. Thus analysis of small molecules (e.g.100-2000 Da) deposited upon the target is possible without matrix interference.
TM-DESITM-DESI is an alternative mode of operation for DESI analysis (2). An electrospray is transmitted through a sampling mesh (e.g. Polypropylene) at 0° angle between spray tip, sample mesh and capillary inlet. Before analysis, the sample is applied to the sample mesh from where it is desorbed by the spray during analysis. This is a simpler approach than traditional DESI for the analysis of liquid samples, since the number of variables to be optimized are reduced.
Water dropplets on coated surfaces
Above: TM-DESI spectrum of NFP 1 (floor coating)Below: TM-DESI spectrum of NFP 2 (tile coating)
Above: NALDI spectrum of NFP 1 (floor coating)Below: NALDI spectrum of NFP 2 (tile coating)
References(1) Daniels RH, Dikler S, Li E, Stacey C. Break Free of the Matrix:
Sensitive and Rapid Analysis of Small Molecules Using Nanostructured Surfaces and LDI-TOF Mass Spectrometry. Journal of the Association for Laboratory Automation 2008 Dec;13(6):314-21.
(2) Chipuk JE, Brodbelt JS. Transmission Mode Desorption Electrospray Ionization. Journal of the American Society for Mass Spectrometry 2008 Nov;19(11):1612-20.
ExperimentalNALDI NFP was diluted 10 times with 2-propanol (NFP 1) or ethanol (NFP 2) and a small amount (few crystals in 10 ml) of NaTFA was added. 1-2 µl of the resulting solution was applied to the NALDI target and allowed to dry at room temperature. Analysis was carried out on a Bruker Autoflex II MALDI-TOF. The mass accuracy was better than 10 ppm for the analysis NFP 1 and better than 30 ppm for the analysis of NFP 2.
TM-DESIA 3 x 3 cm polypropylene mesh (open space: 297 µm) was dipped into undiluted NFP and then analysed directly hereafter. A solution of methanol/water 1:1 with 1 % formic acid and a few crystals of ammonium acetate was used as electrospray solvent at flow rates of 5-10 µl/min. Nitrogen was used as nebulization gas at a pressure of 10 Bar. The electrospray voltage was -4.5 kV applied to MS inlet capillary which was kept at 250 °C. The TM-DESI experiments were carried out on a Bruker micrOTOF-Q instrument equipped with an in-house built DESI source. The mass accuracy was better than 1.5 ppm.
In case of NFP 2, addition of NaTFA improved signal intensity by a factor 2-3. The ions observed in NALDI analysis of the NFPs were therefore all sodium adducts; NFP 1 mainly yielded ions which had eliminated HF as a neutral loss,
+[(M-HF)+Na] , while NFP 2 yielded both + + [M+Na] and [(M+Na)Na] ions.
•In TM-DESI analysis of NFP 1, ammonia +adducts, [M+NH ] , were more abundant 4
than both the sodium adduct and the quasi molecular ions. Addition of a small amount of ammonium acetate to the electrospray solvent increased the signal intensity by at least 100 times.
+•TM-DESI of NFP 2 resulted in [M+H] ions regardless of the addition of ammonia acetate.
Conclusions•Both NALDI and TM-DESI are suitable for analysis of NFPs based on functionalised silanes.
•NALDI yielded more information on the polysiloxanes; this is probably due to film formation on NALDI target taking place by condensation reactions.
•Addition of salts were critical for the ionization efficiency in both methods.
•The demonstrated usefulness of desorption ionization methods for NFP analysis, form the basis for future studies of the film formation process.
•Both NALDI and TM-DESI analysis of the NFPs showed the silanes and siloxanes of 1H,1H,2H,2H-perfluorooctyltriisopropoxysilane (NFP 1) and hexadecyltriethoxysilane (NFP 2) with different degrees of hydrolyzation and condensation.
•The mass accuracy in NALDI and especially TM-DESI experiments enabled determination of sum formulas which, in combination with MS/MS experiments, facilitated the identification.
•NALDI showed the silanes and their polysiloxanes for both products; up to tetrasiloxanes for NFP 1 and up to decasiloxanes for NFP 2, while TM-DESI showed trisiloxanes for NFP 1 and disiloxanes for NFP 2.
•Addition of NaTFA was found to be critical for the NALDI analysis of NFP 1.
Desorption ionization analysis of nano film products for surface coating: A comparison of NALDI and TM-DESI
1 2 2 1Asger W. Nørgaard , Christian Janfelt , Frants R. Lauritsen and Peder Wolkoff 1) National Research Centre for the Working Environment, Copenhagen, Denmark
2) Faculty of Pharmaceutical Sciences, University of Copenhagen, [email protected]
IntroductionNanoFilm Products (NFPs) are a relatively new type of consumer products for surface coating e.g. bathroom tiles, floors, textiles etc. The products are sprayed onto a surface, whereupon a thin coating is formed during evaporation of the solvent. This coating induces non-stick and in some cases self cleaning properties to the treated surface. In this study, two products, NFP 1 (floor coating) and NFP 2 (tile coating), were selected for analysis by two desorption ionization techniques, Nano Assisted Laser Desorption Ionization (NALDI) and Transmission Mode Desorption Electrospray Ionization (TM-DESI). Both methods are simple to use and require a minimum of sample preparation. The two methods were compared and the results are presented below.
Hydrolysates and condensates of 1H,1H,2H,2H-perfluorooctyltriisopropoxysilane
NALDI: [(M-HF)+Na]+ at m/z 555.091TM-DESI: [M+H]+ at m/z 553.1429
Si
OC3H7
H7C3O
C8H4F13
OC3H7Si O Si
OH
F13H4C8
OC3H7 OC3H7
OC3H7
C8H4F13
Si O Si
OC3H7
F13H4C8
OC3H7 O
OC3H7
C8H4F13
SiH7C3O
C8H4F13
OC3H7
OC H
F
C H F
F
Si O Si
3 7
13H4C8
O O
OC3H7
8 4 13
SiO
C8H4F13
OC3H7Si13H4C8
OC3H7
n
Si OO
O
C8H4F13
X
X X
X = H, C3H7 or C8H4F13O2Si-Y where Y = H or C3H7
General formula:
[(M-HF)+Na]+ at m/z 963.098
OC H C H F
Si O Si
3 7
F13H4C8
OC3H7 OC3H7
OC3H7
8 4 13
Silane DisiloxaneNALDI:
[M+NH4]+ at m/z 1020.2033
TM-DESI:
Trisiloxane
NALDI: [(M-HF)+Na]+ at m/z 1455.183TM-DESI: [M+NH4]+ at m/z 1470.2357
Tetrasiloxane
NALDI: [(M-HF)+Na]+ at m/z 1803.064
Hydrolysates and condensates of 1H,1H,2H,2H-perfluorooctyltriisopropoxysilane
NALDI: [(M-HF)+Na]+ at m/z 555.091TM-DESI: [M+H]+ at m/z 553.1429
Si
OC3H7
H7C3O
C8H4F13
OC3H7Si
OC3H7
H7C3O
C8H4F13
OC3H7Si O Si
OH
F13H4C8
OC3H7 OC3H7
OC3H7
C8H4F13
Si O Si
OH
F13H4C8
OC3H7 OC3H7
OC3H7
C8H4F13
Si O Si
OC3H7
F13H4C8
OC3H7 O
OC3H7
C8H4F13
SiH7C3O
C8H4F13
OC3H7
Si O Si
OC3H7
F13H4C8
OC3H7 O
OC3H7
C8H4F13
SiH7C3O
C8H4F13
OC3H7
OC H
F
C H F
F
Si O Si
3 7
13H4C8
O O
OC3H7
8 4 13
SiO
C8H4F13
OC3H7Si13H4C8
OC3H7
OC H
F
C H F
F
Si O Si
3 7
13H4C8
O O
OC3H7
8 4 13
SiO
C8H4F13
OC3H7Si13H4C8
OC3H7
Si O Si
3 7
13H4C8
O O
OC3H7
8 4 13
SiO
C8H4F13
OC3H7Si13H4C8
OC3H7
n
Si OO
O
C8H4F13
X
X X
X = H, C3H7 or C8H4F13O2Si-Y where Y = H or C3H7
General formula:
n
Si OO
O
C8H4F13
X
X X
X = H, C3H7 or C8H4F13O2Si-Y where Y = H or C3H7
General formula: Si OO
O
C8H4F13
X
X X
X = H, C3H7 or C8H4F13O2Si-Y where Y = H or C3H7
Si OO
O
C8H4F13
X
X X
X = H, C3H7 or C8H4F13O2Si-Y where Y = H or C3H7
General formula:
[(M-HF)+Na]+ at m/z 963.098
OC H C H F
Si O Si
3 7
F13H4C8
OC3H7 OC3H7
OC3H7
8 4 13
Si O Si
3 7
F13H4C8
OC3H7 OC3H7
OC3H7
8 4 13
Silane DisiloxaneNALDI:
[M+NH4]+ at m/z 1020.2033
TM-DESI:
Trisiloxane
NALDI: [(M-HF)+Na]+ at m/z 1455.183TM-DESI: [M+NH4]+ at m/z 1470.2357
Tetrasiloxane
NALDI: [(M-HF)+Na]+ at m/z 1803.064
Hydrolysates and condensates of hexadecyltriethoxysilane
Si O
O
O
C16H33
X
X
X
n
X = H, C2H5 or C16H33O2Si-Y where Y = H or C2H5
General formula:
Si O Si
OH
H33C16
OC2H5 O
OC2H5
C16H33
SiH5C2O
C16H33
OH
Si O Si
OH
H33C16
OC2H5 OC2H5
OC2H5
C16H33
Si
OC2H5
H5C2O
C16H33
OC2H5
[(M+Na]+ at m/z 383.303
Silane Disiloxane
Trisiloxane Tetrasiloxane
Si
OC2H5
HO
C16H33
OC2H5
NALDI:
TM-DESI: [M+H]+ at m/z 389.3447 NALDI: [(M+Na]+ at m/z 697.566TM-DESI: [M+H]+ at m/z 675.5760
NALDI: [(M+Na]+ at m/z 983.776 NALDI: [(M+Na]+ at m/z 1241.910
S i O S i
O
H 3 3 C 1 6
O C 2 H 5O
O H
C 1 6 H 3 3
S iH 5 C 2 O
C 1 6 H 3 3
O H
S iH O O H
C 1 6 H 3 3
Hydrolysates and condensates of hexadecyltriethoxysilane
Si O
O
O
C16H33
X
X
X
n
X = H, C2H5 or C16H33O2Si-Y where Y = H or C2H5
General formula: Si O
O
O
C16H33
X
X
X
n
X = H, C2H5 or C16H33O2Si-Y where Y = H or C2H5
Si O
O
O
C16H33
X
X
X
n
X = H, C2H5 or C16H33O2Si-Y where Y = H or C2H5
General formula:
Si O Si
OH
H33C16
OC2H5 O
OC2H5
C16H33
SiH5C2O
C16H33
OH
Si O Si
OH
H33C16
OC2H5 OC2H5
OC2H5
C16H33
Si
OC2H5
H5C2O
C16H33
OC2H5
[(M+Na]+ at m/z 383.303
Silane Disiloxane
Trisiloxane Tetrasiloxane
Si
OC2H5
HO
C16H33
OC2H5
NALDI:
TM-DESI: [M+H]+ at m/z 389.3447 NALDI: [(M+Na]+ at m/z 697.566TM-DESI: [M+H]+ at m/z 675.5760
NALDI: [(M+Na]+ at m/z 983.776 NALDI: [(M+Na]+ at m/z 1241.910
S i O S i
O
H 3 3 C 1 6
O C 2 H 5O
O H
C 1 6 H 3 3
S iH 5 C 2 O
C 1 6 H 3 3
O H
S iH O O H
C 1 6 H 3 3
Si O Si
OH
H33C16
OC2H5 O
OC2H5
C16H33
SiH5C2O
C16H33
OH
Si O Si
OH
H33C16
OC2H5 O
OC2H5
C16H33
SiH5C2O
C16H33
OH
Si O Si
OH
H33C16
OC2H5 OC2H5
OC2H5
C16H33
Si O Si
OH
H33C16
OC2H5 OC2H5
OC2H5
C16H33
Si
OC2H5
H5C2O
C16H33
OC2H5Si
OC2H5
H5C2O
C16H33
OC2H5
[(M+Na]+ at m/z 383.303
Silane Disiloxane
Trisiloxane Tetrasiloxane
Si
OC2H5
HO
C16H33
OC2H5Si
OC2H5
HO
C16H33
OC2H5
NALDI:
TM-DESI: [M+H]+ at m/z 389.3447 NALDI: [(M+Na]+ at m/z 697.566TM-DESI: [M+H]+ at m/z 675.5760
NALDI: [(M+Na]+ at m/z 983.776 NALDI: [(M+Na]+ at m/z 1241.910
S i O S i
O
H 3 3 C 1 6
O C 2 H 5O
O H
C 1 6 H 3 3
S iH 5 C 2 O
C 1 6 H 3 3
O H
S iH O O H
C 1 6 H 3 3
333.2834
361.3129
389.3447
675.5760
647.5445
0
1
2
3
4
5
6
100 200 300 400 500 600 m/z
x104
Inte
ns
.[a
.u.]
Disiloxanes
Silanes
411.3249
[M1+Na]+
[M1+H]+
[M2+H]+
[M3+Na]+
333.2834
361.3129
389.3447
675.5760
647.5445
0
1
2
3
4
5
6
100 200 300 400 500 600 m/z
x104
Inte
ns
.[a
.u.]
333.2834
361.3129
389.3447
675.5760
647.5445
0
1
2
3
4
5
6
100 200 300 400 500 600 m/z
x104
Inte
ns
.[a
.u.]
Disiloxanes
Silanes
411.3249
[M1+Na]+
[M1+H]+
[M2+H]+
[M3+Na]+
Polypropylene mesh
MS-inlet (-4.5 kV)
Sprayer angle fixed at 0º
Grounded sprayer
TM-DESI on a Bruker micrOTOF-Q instrument
Results
449.390
1455.183
963.098
1353.080
555.091
1803.064
685.467 2188.989 2935.6690
1
2
3
4
x104
Inte
ns.
[a.u
.]
500 1000 1500 2000 2500 3000m/z
1455.183
1353.080
1433.200
1413.1291311.028
1391.149 1475.2581331.0880.00
0.25
0.50
0.75
1.00
1.25
1.50
1250 1300 1350 1400 1450
Silanes
Disiloxanes
Trisiloxanes
Tetrasiloxanes
[M1+Na]+
[(M1-HF)+Na]+
[M2+Na]+
[(M2-HF)+Na]+
[(M3-HF)+Na]+
[(M4-HF)+Na]+
Trisiloxanes
449.390
1455.183
963.098
1353.080
555.091
1803.064
685.467 2188.989 2935.6690
1
2
3
4
x104
Inte
ns.
[a.u
.]
500 1000 1500 2000 2500 3000m/z
1455.183
1353.080
1433.200
1413.1291311.028
1391.149 1475.2581331.0880.00
0.25
0.50
0.75
1.00
1.25
1.50
1250 1300 1350 1400 1450
449.390
1455.183
963.098
1353.080
555.091
1803.064
685.467 2188.989 2935.6690
1
2
3
4
x104
Inte
ns.
[a.u
.]
500 1000 1500 2000 2500 3000m/z
449.390
1455.183
963.098
1353.080
555.091
1803.064
685.467 2188.989 2935.6690
1
2
3
4
x104
Inte
ns.
[a.u
.]
500 1000 1500 2000 2500 3000m/z
1455.183
1353.080
1433.200
1413.1291311.028
1391.149 1475.2581331.0880.00
0.25
0.50
0.75
1.00
1.25
1.50
1250 1300 1350 1400 1450
1455.183
1353.080
1433.200
1413.1291311.028
1391.149 1475.2581331.0880.00
0.25
0.50
0.75
1.00
1.25
1.50
1250 1300 1350 1400 1450
Silanes
Disiloxanes
Trisiloxanes
Tetrasiloxanes
[M1+Na]+
[(M1-HF)+Na]+
[M2+Na]+
[(M2-HF)+Na]+
[(M3-HF)+Na]+
[(M4-HF)+Na]+
Trisiloxanes
697.566
430.931
983.7761241.910
1528.020
1814.083
2101.103
2387.0882673.054
2986.989
0.0
0.5
1.0
1.5
2.0
2.5
x104
Inte
ns.[a
.u.]
500 1000 1500 2000 2500 3000m/z
697.566
669.533
725.598
641.498691.512 719.545
0.0
0.5
1.0
1.5
620 640 660 680 700 720
383.303Silanes
Disiloxanes
TrisiloxanesTetra
Penta
Hexa
Hepta
OctaNona Deca
Trisiloxanes
[M1+Na]+
[(M2+Na)Na]+[(M3+Na)Na]+
[M2+Na]+
[M3+Na]+
[M4+Na]+
697.566
430.931
983.7761241.910
1528.020
1814.083
2101.103
2387.0882673.054
2986.989
0.0
0.5
1.0
1.5
2.0
2.5
x104
Inte
ns.[a
.u.]
500 1000 1500 2000 2500 3000m/z
697.566
669.533
725.598
641.498691.512 719.545
0.0
0.5
1.0
1.5
620 640 660 680 700 720
383.303
697.566
430.931
983.7761241.910
1528.020
1814.083
2101.103
2387.0882673.054
2986.989
0.0
0.5
1.0
1.5
2.0
2.5
x104
Inte
ns.[a
.u.]
500 1000 1500 2000 2500 3000m/z
697.566
669.533
725.598
641.498691.512 719.545
0.0
0.5
1.0
1.5
620 640 660 680 700 720
669.533
725.598
641.498691.512 719.545
0.0
0.5
1.0
1.5
620 640 660 680 700 720
383.303Silanes
Disiloxanes
TrisiloxanesTetra
Penta
Hexa
Hepta
OctaNona Deca
Trisiloxanes
[M1+Na]+
[(M2+Na)Na]+[(M3+Na)Na]+
[M2+Na]+
[M3+Na]+
[M4+Na]+
469.0489
1020.2033
1428.1904
0.0
0.5
1.0
1.5
200 400 600 800 1000 1200 1400 m/z
x104
Inte
ns.
[a.u
.]
961.1275
978.1544
1003.1771
1020.2033
0.0
0.5
1.0
1.5
950 960 970 980 990 1000 1010 1020
Silanes
DisiloxanesDisiloxanes
Trisiloxanes
[M1+NH4]+
[M1+H]+
[M2+H]+
[M2+NH4]+
469.0489
1020.2033
1428.1904
0.0
0.5
1.0
1.5
200 400 600 800 1000 1200 1400 m/z
x104
Inte
ns.
[a.u
.]
469.0489
1020.2033
1428.1904
0.0
0.5
1.0
1.5
200 400 600 800 1000 1200 1400 m/z
x104
Inte
ns.
[a.u
.]
961.1275
978.1544
1003.1771
1020.2033
0.0
0.5
1.0
1.5
950 960 970 980 990 1000 1010 1020
961.1275
978.1544
1003.1771
1020.2033
0.0
0.5
1.0
1.5
950 960 970 980 990 1000 1010 1020
Silanes
DisiloxanesDisiloxanes
Trisiloxanes
[M1+NH4]+
[M1+H]+
[M2+H]+
[M2+NH4]+