1

1

ANALYTICAL ATOMIC SPECTROSCOPY WITH THE INDUCTIVELY COUPLED PLASMA

R. S. HOUK

ICP BASICS

ICP ATOMIC EMISSION SPECTROMETRY

ICP MASS SPECTROMETRY

LASER ABLATION

2

RAFAEL FERNANDESU. MINNESOTA

2

3

IE

ATOMIC SPECTROSCOPY

M 0

M*

(M +)0

(M +)* ATOMIC LEVELS

NO VIB - ROT SUBLEVELSSHARP LINESHIGH SELECTIVITY(+)

ONLY DETERMINE ELEMENTNOT COMPOUND (-)

AAAE

PRODUCE FREE ATOMSFROM SAMPLE ?EXCITE EMISSION (AE)

4

ATOMIZE & EXCITE SAMPLE

MX (aq) → MX (aq, aerosol) → MX (s, aerosol) → MX (g)

M 0 (g) + X (g)

M*

(M +)0

(M +)*

M 0(M +)0

ION LINESM (II)Higher E,shorter λ than I lines

ATOMLINES M (I)

Nebulization Desolvation

Vaporization

Atom’nIonization

Excitationabsorption

Emission

3

5ICP

NORMAL ANALYTICAL ZONE (blue )

INITIAL RAD. ZONE (red)

INDUCTION REGION

OUTER GAS FLOW

AEROSOL GAS FLOW INTO AXIAL CHANNEL

LOADCOIL

TORCH

6

Yttrium Emission Zones

Y+ LinesYO Bands

Y Neutral Lines

4

7

Diffraction Gratings

8

5

9

10

Winge

6

11

MANY VALENCE ELECTRONSMANY ENERGY LEVELSCOMPLEX EMISSION SPECTRA

12

7

13

14

SAMPLER SKIMMER

IONLENS

ION SAMPLING FOR ICP-MS

8

15

16AT SPOT USUALLY USED IN ICP-MS:

Just off tip of initial radiation zone

Tgas = 6000 K ntotal = P/RTgas = 1.5 x 1018 cm-3

mostly Ar

ne = n+ = 1 x 1015 cm-3

Flow velocity ~ 25 m/s

Residence time ~ 2 ms

9

17DISSOCIATION

MO+ M+ + O Kd = (nM+ nO)/nMO+

∆H = D0 (MO+)

20.274 Z

z z log

M

M M log 1.5

T

D 5040 - T log 1.5 )(cm K log

MO

Oelec

Melec

MO

oM

gas

0gas

3-d

+′

+

+=

+

+

+

+

nM+ / nMO+ INCREASES AS:D0 <Tgas >nO <

18IONIZATION SAHA EQUATION

M M+ + e- K ion = nM+ ne/nM

∆H = IE (M)

15.684 z

z log

T

IE 5040 - T log 1.5 )(cm K log

Melec

Melec

ionion

3-ion

++

=

+

SIMILAR RELATIONSHIP FORM+ M 2+ + e-

10

19IONIZATION IN ICP

T = 7500 K ne = 1 x 1015 cm-3

Y Zr Nb

La Ta

Ac

Co Cu Zn

B C N O F

He

Ne

Al Si P S Cl Ar

Ga Ge As Se Br Kr

Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe

W Re Os Ir Pt Au Hg Tl Pb Po At Rn

Cr Mn Fe Ni

Hf Bi

Fr Ra

Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lw

H

Li Be

Na

K Ca

Rb Sr

Cs Ba

VSc Ti

0.1

100 75

100 98Mg

100 100 99 99 98 95 96 93 91 90 75 90

98

98

98 94 93 93 8596

94 93 78 62 51 38 100

99 96 78 66 29 8.5

92

58 5 0.1 0.1 9e-4 6e-6

85 33 14 0.9 0.04

52 33 5 0.6

100

100

96,4

91,9

98

90,10

99,1

97,0.0196 95

96,2 90,10 99* 97,3 100* 93,7 99* 100*

100* 100*

99* 91,9 92,8

99 98

*These elements also make M+2

M+/(M+ + M) (%)

%M 2+

20

ICP + QUADRUPOLE MASS SPECTROMETER

11

0

5000000

10000000

15000000

20000000

25000000

30000000

135 136 137 138 139 140 141 142 143 144

21

0

1E+09

2E+09

3E+09

4E+09

5E+09

6E+09

7E+09

8E+09

9E+09

135 136 137 138 139 140 141 142 143 144

140Ce+

8e6 c/s

138Ce+

2e4 c/s

0

20000000

40000000

60000000

80000000

100000000

120000000

140000000

160000000

180000000

150 151 152 153 154 155 156 157 158 159 160

140Ce16O+

1.3e5 c/s

140Ce2+

1.6e5 c/s

m/z RATIO

ION

SIG

NA

L10 ppb Ce

22ICP-MS CAPABILITIES

DETECTION LIMITS 0.1 - 10 ppt routine10 ppq SOME INSTS.USUALLY BLANK-LIMITED

TOTAL SOLUTES 0.1% USUALLY OK1% USUALLY PROBLEMSUNLESS USE FLOW INJECTION

PRECISION 3% RSD ROUTINE1% GOOD1% ROUTINE W. INT. STDS.

ACCURACY COMPARABLE TO PRECISION IFCOMPENSATE FOR INTERFERENCES

12

23INTERFERENCES (REL. TO ICP-AES)

SPECTRAL LESS FREQUENTOVERLAP LESS SEVERE

MORE PREDICTABLEEASIER TO CORRECT

MATRIX WORSE ININTS. ICP-MS

- PLUGGING- CHANGE OF SIGNAL(usually loss)

24

APPLICATION AREAS

1. ENVIRONMENTAL ANALYSISSTANDARD METHODS

2. GEOCHEMISTRYRARE EARTHSPROSPECTING, Pt GROUP ELEMENTSU-Th-Pb DATINGLASER ABLATION

3. SEMICONDUCTORSDIW, MINERAL ACIDSORGANIC SOLVENTSSURFACE LAYERS, VAPOR-PHASE DECOMP..

13

25

Wafer Surface Preparation by VPDVapor Phase Decomposition

Wafer Surface Preparation by VPDVapor Phase Decomposition

• native oxide layer SiO2

• dissolve native oxide layer

• soluble contaminants in fluorosilicic acid

• integral wafer contamination can be collected in

one droplet

Si Wafer Analysis

26

Wafer Preparation by VPD (1,2)Wafer Preparation by VPD (1,2)

Gaseous HF to SiO2 Deposition of HF(aq) film

a) b)

14

27

Wafer Preparation by VPD (3,4)Wafer Preparation by VPD (3,4)

Etching of SiO2 Surface Scan for Collecting Contaminants

c) d)

28

Wafer Preparation by VPD Wafer Preparation by VPD

e) f)

adding scanning solutionand surface scan

ROLL AQUEOUS ACID DROPLETAROUND ETCHED SAMPLE SURFACE,COLLECT CONTAMINANTS

*Si SURFACE HYDROPHOBICACID DROPLET NOT DISPERSED OVER SURFACE!

TO NEBULIZER& ICP-MS

15

29

APPLICATION AREAS

4. NUCLEAR INDUSTRYRADIONUCLIDESPURITY OF MATERIALS

5. BIOMEDICALFLUIDS & TISSUESMETALS IN PROTEINS & ENZYMES

6. FORENSICSMATCHING EVIDENCE BASED ON TRACE ELEMENT COMPOSITION

16

31

Th SOLN 1000 ppmSUM OF 3 SPECTRA

Th SOLN.SUM OF 60 SPECTRA

BLANK

32

17

33

SAMPLE INTROCONCENTRIC PNEUMATIC NEBULIZER

• 100% Teflon

• Self-aspiration:– 20 µL/min

– 50 µL/min

– 100 µL/min

– 400 µL/min

34ION EXTRACTION

18

35COLOR SLIDES OF SAMPLER - SKIMMER REGIONCONDITIONS INSIDE SAMPLER

FLOW THROUGH SAMPLER = G 0 = 0.445 n0a0D02

a0 = speed of sound in source = (kTgas,0/m)1/2

D0 = orifice diam. n0 ~ P/RTgas

TYPICAL G 0 ~ 1021 atoms/s

DEBYE LENGTH = λD = (ε0kTe/e2ne)1/2

λD (cm) = 6.9 (Te/ne)1/2 Te in K ne in cm-3 (NEXT SLIDE)Te ~ 8000 K ne ~ 1015 cm-3

INSIDE SAMPLER λD ~ 10-4 mm << D0

SO PLASMA REMAINS QUASINEUTRALAS FLOWS THROUGH SAMPLER

36

λD

Chen, Intro to Plasma Physics, 1984

19

37

S. JET & SKIMMING PROCESS

Barrel shock

Skimmer

Directed flowin zone of silence

Collisions

ICPT ~ 6000 K

v (Ar)

IN JETT ~ 300 K

N(v)

N(v)

VELOCITY

VELOCITY

- 0 +

38

Sampler

Skimmer

Photo by A. L. Gray

20

39

SAMPLERSKIMMER

ICP:Tion ~ 7000 KTgas~ 6000 K

AT SKIMMER:Tion ~ 7000 KTgas~ 155 KTIME ~ 3 µs ~250 colls with Ar

EXTRACTION PROCESSDouglas & French JAAS 1988

40CONDITIONS INSIDE SKIMMER TIP

FLOW THROUGH SKIMMER = G 1 = n(xs)v(xs)As

v = velocity ~ (5kT0/2m)1/2 As = area of skimmer

TYPICAL G 1 ~ 1 x 1019 atoms/s ~ 1% OF FLOW THROUGH SAMPLER

ALSO GOES THRU SKIMMER λD (cm) = 6.9 (Te/ne)1/2 ne NOW ~1012 cm-3

INSIDE SKIMMER λD ~ 10-2 mm << Ds

SO PLASMA ALSO REMAINS QUASINEUTRALAS FLOWS THROUGH SKIMMERALTHOUGH MAY BE SIGNIFICANT SHEATH INSIDE SKIMMER TIP

21

41

42ION LENS

V1 V2

+

+

V1, V2 NOT DEP. ON m/z UNLESS:

- IE = f (m/z)-SPATIAL DIST. = f (m/z)

Equipotential contours

22

43SIMION - EINZEL LENS

0 +110 0 volts

0 +140 0 volts

INITIAL ION KE= 200 eV

FOCAL POSITIONVARIES WITHAPPLIED VOLTAGE

44

EINZEL LENS

INITIAL KE=200 eV

230 eV

FOCAL POSITIONVARIES WITHINITIAL ION KE

23

45

46

24

47

QUADRUPOLE MASS ANALYZER

y

x

U + V cos ωt

- (U + V cos ωt)

Thermo Elemental

BRUKER AURORA ELITE(now Analytik Jena)

25

49

Quad lenses

Extraction lensesSkimmer

Sampler

Entranceslit

Magnet& flighttube

ESA

DetectorELEMENTSCANNING HIGH RESICP-MS DEVICE

ICP

Neb &Spray chamber

50

64Zn+

66Zn+

67Zn+

68Zn+

70Zn+

10 ppb ZnPFA 100

26

51

Spectra

PEAK SHAPES LOW & HIGH RES.

52Photoresist Interferences on Cu

12C5H3+

12CH332S16O+

63Cu+

27

53

54

MATRIX EFFECTOlivares & Houk, Anal. Chem 1986, 58, 20.

28

55

56INTERNAL STANDARD

Co+

29

57REMOVE POLYATOMIC IONS?

12C5H3+

12CH332S16O+

63Cu+

58GOOD IE BAD IE D 0GUYS/GALS (eV) GUYS (eV) (eV)S+ 10.36 O2

+ 12.063 6.663

Fe+ 7.87 ArO+ ~ 13 0.312ArN + ~14 1.866

Se+ 9.75 Ar2+ ~15 1.25

K+ 4.34 ArH+ ~10 4.00*

V+ 6.74 ClO+ 11.1 4.65

Ti + 6.82 SO+ 10.0 5.43

Zn+ 9.39 SO2+ 12.34

30

BRUKER AURORA ELITE

ADD H2 &/or HeREMOVE

POLYATOMIC IONS?

60

31

61

LASER ABLATION

Laser Ablation ICP-MS

CETAC LSX 500

Thermo Finnigan Elementwww.cetac.com

www.thermo.com

32

Lasers

Laser Coherent Libra Cetac LSX-500

Lasing Medium Ti:Sapph Nd:YAG

Wavelength 800 nmTriple to 266 nm

1064 nmQuadruple to 266 nm

Pulse length ~100 fs ~6 ns

Repetition rate 1000 Hz 10 Hz

Pulse energy 0.20 mJ 9.0 mJ

Laser power ~76 W ~90 W

33

65DEVELOPMENTS IN LASER ABLATION

GÜNTHER et al., ANAL. CHEM. 2003, 75, 341A; TrAC 2005, 24, 255.

UV LASERS (266 , 213, 193 nm)HOMOGENIZED BEAM PROFILEHELIUM TRANSPORT GAS

FRACTIONATION1. VARIATION OF SIGNAL RATIO vs TIME

AS DIG SINGLE PIT2. MEAS. SIGNAL RATIOS

DIFFER FROM THOSE IN SAMPLE

SOLUTIONS:FLAT BOTTOM CRATERSVERTICAL SIDESSHORT PULSE (fs) LASER(RUSSO et al., ANAL. CHEM. 2002, 74, 70A).

66

34

67

68

35

69

Particles from Ablated Y2O3 Pellet

Track length →velocity ~ 27 m/s

70

Pressed pelletFernald soil blank

36

COHERENT LIBRA100 fs 266 nm

72

fs LASER ns LASER

31 µm/s scan rate, NIST brass C1102

100 kHz Rep. Rate, ~ 50 µm spot size 20 Hz Rep. Rate, 50 µm spot size

0.0E+00

3.0E+05

6.0E+05

9.0E+05

1.2E+06

0 6 12 18

Time (s)

Sn

Sig

nal (

cps)

0.0E+00

6.0E+07

1.2E+08

1.8E+08

0 6 12 18

Time (s)

Zn S

igna

l (cp

s)

0.00E+00

6.00E+07

1.20E+08

1.80E+08

0 6 12 18

Time (s)

Zn S

igna

l (cp

s)

0.0E+00

3.0E+05

6.0E+05

9.0E+05

1.2E+06

0 6 12 18

Time (s)

Sn S

igna

l (cp

s)

37

0.0 ms 0.1 ms 0.2 ms

0.3 ms 0.4 ms 0.5 ms

0.6 ms 0.7 ms 0.8 ms

fs argon 610

74

38

75

CALIBRATE LASER ABLATION?

COMPENSATE FOR MATRIX DEPENDENCEOF ABLATION PROCESS

MATCHED STANDARDS

MEAS. ANALYTE REL. TO MINOR ISOTOPEOF ELEMENT AT KNOWN CONCENTRATION

CALIBRATE REL. TO SOLUTION AEROSOL?BECKER JAAS 2001, 16, 603-606.AESCHLIMAN JAAS 2003, 18, 872-877.

76

pump

CETAC LASER ABLATION SYSTEM TSI PIEZOBALANCE

FINNIGAN

ICP-MS

ESI NEBULIZER

Nd:YAG laser (266 nm)

camera

translation stage

argon inlet

zoom lens

impactorelectrostatic precipitator

calibration solution

waste90%

10%

20%

80%

ICP

ESA

magnet

argon inlet

39

77

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 100 200 300 400 500 600 700

Time (s)

Sig

nal (

coun

ts s-1

) / 1

06

60Ni+

51V+52Cr+

NIST STEEL

Solution

Ablatedsolid

NIST 612 Glass (13 Elements, 5 Replicates)• Particle transport from the LA cell was measured using a piezoelectric microbalance• Each replicate was generated by firing 50 laser shots per localized spot on the sample• A two-point calibration plot for each replicate was prepared and an average calculated• All elements were measured in medium resolution (R = m/∆m = 4000)

CONCENTRATION (ppm)MEASURED CERTIFIED Relative Diff. (%)

Mn (55Mn+) 40.8 ± 7.9 (39.6) 3.0Fe (56Fe+) 51.6 ± 6.1 51 1.2Co (59Co+) 36.0 ± 4.7 (35.5) 1.4Ni (60Ni+) 39.2 ± 4.7 38.8 1.0Cu (63Cu+) 38.5 ± 6.7 (37.7) 2.1Ba (138Ba+) 41.6 ± 5.5 (41) 1.5Nd (146Nd+) 36.2 ± 2.6 (36) 0.56Sm (147Sm+) 39.5 ± 4.7 (39) 1.3Eu (151Eu+) 36.5 ± 4.7 (36) 1.4Dy (161Dy+) 35.1 ± 2.5 (35) 0.29Er (166Er+) 39.3 ± 4.2 (39) 0.77Tl (205Tl+) 15.8 ± 1.6 (15.7) 0.64Pb (208Pb+) 39.2 ± 5.8 38.57 1.6

40

79NIST 1264a Steel (8 Elements)• 266 nm QUAD. Nd:YAG LASER, CETAC LSX-100• AVG. 30 SPOTS, TWO-POINT STD. ADDNS.• 50 SHOTS PER SPOT, MED. RES.• PARTICLE TRANSPORT MEAS. WITH MICROBALANCE

CONCENTRATION (wt %)MEAS. CERT. (INFO)

V (51V+) 0.119± 0.029 0.106Cr (52Cr+) 0.073± 0.012 0.066Co (59Co+) 0.156± 0.017 0.150Ni (60Ni+) 0.143± 0.017 0.142Cu (63Cu+) 0.248± 0.040 0.250W (184W+) 0.107± 0.027 0.102Pb (208Pb+) 0.056± 0.055 0.024Bi (209Bi+) 0.0016± 0.0032 (0.0009)

80NIST 1264a Steel (8 Elements)• 193 nm ArF LASER• AVG. 3 SPOTS, TWO-POINT STD. ADDNS.• 50 SHOTS PER SPOT, MED. RES.• PARTICLE TRANSPORT MEAS. WITH MICROBALANCE

CONCENTRATION (wt %)MEAS. CERT. (INFO)

V (51V+) 0.115± 0.011 0.106Cr (52Cr+) 0.078± 0.036 0.066Co (59Co+) 0.137± 0.035 0.150Ni (60Ni+) 0.139± 0.108 0.142Cu (63Cu+) 0.277± 0.201 0.250W (184W+) 0.108± 0.013 0.102Pb (208Pb+) 0.021± 0.004 0.024Bi (209Bi+) 0.0006± 0.0001 (0.0009)

41

81

82COLLISION CELLS

Rowan & Houk, Appl. Spectrosc. 1989, 43, 976.Douglas, Canad. J. Spectrosc. 1989, 34, 38.King & Harrison, Int. J. Mass Spectrom. Ion Processes1989, 89, 171.

Turner, Speakman et al., Plasma Source MS, Developments & Applications, Royal Society, 1997, p. 28.

Baranov & Tanner, JAAS 1999, 14, 1133JASMS 1999, 10, 1083.

USE COLLISION - INDUCED DISSOCIATION (CID) &/OR CHEMICAL REACTION TO REMOVE POLY. IONS

RETAIN ATOMIC ANALYTE IONSREDUCE KE & SPREAD OF KE OF M+ IONS

42

83

ions from source

conversion of reactive ions

mass analysis of transmitted ions

ions to detector

isobaranalyteother m/z

reaction gas inreaction cellmass analyzer

DYNAMIC REACTION CELL (DRC)

84

0.05 0.15 0.25 0.35 0.45 0.55 0.65 0.75 0.85 0.95

CH4 FLOW RATE (L/min)

1

10

100

1000

1e4

1e5

1e6

1e7

m/z = 801 ppb Se80Se+ + CH4 → no rxn.

m/z = 781 ppb Se

m/z = 821 ppb Sem/z = 80 blank

40Ar2+ + CH4 → prods

m/z = 78 blank38Ar40Ar+ + CH4

→ products

REACTION PROFILES

m/z = 80 1 ppb Se40Ar2

+ + CH4 → products

43

85

m/z = 75

ION

SIG

NA

L

1 ppb As750 c/s

1 ppb As+ 1000 ppm NaCl

1000 ppm NaCl25 c/s

DIW

DEATH TO ArCl + !

86

OCTOPOLE COLLISION CELL

44

87KINETIC ENERGY DISCRIMINATION

COLL CELL LENGTH L = 10 cmGAS DENSITY n

ION HAS CROSS SECTION Ω (cm2)

NUMBER OF COLLISIONS = L/ λ = L n Ωλ = mean free path (cm)

EXPECT ~ 5 TO 10 COLLISIONS

POLY ION IS LARGERLARGER ΩMORE COLLISIONS IN SAME LENGTH L

88

( )

( ) He with ArO and Fe of collfor 0.88 56 4

56 4~

m m

m m ~ collper remaining KE ofFraction

TIONDISCRIMINA KE & LOSSES KE

2

22

2iongas coll

2ion

2gas coll

++=++

++

=

α

α

SAY Fe+ HAS 5 COLLS ArO + HAS 10 COLLS

Fe+ HAS α5 = 0.885 = 0.52 OF INITIAL KE REMAINING ArO + HAS α10 = 0.8810 = 0.28 OF INITIAL KE

Covey & Douglas JASMS 1993 p 616

45

89

0

100

200

300

400

500

600

00.4

0.8

1.2

1.6 2

Analyte

Interferent

KE

N

KINETIC ENERGY DISCRIMINATION

NO COLL. GAS

90

0

100

200

300

400

500

600

00.4

0.8

1.2

1.6 2

Analyte

Interferent

KE

N

POLY. ION HAS LARGER CROSS SECTION FOR KE LOSS

POTENTIAL BARRIERON QUADRUPOLESTOPS POLY. IONS

46

91

Unspiked 5% HNO3 + 5% HCl + 1% H2SO4 + 1% IPA Matrix

2E5cps

92

All polyatomic interferences are removed in He Mode

Unspiked 5% HNO3 + 5% HCl + 1% H2SO4 + 1% IPA MatrixALL polyatomic interferences are removed in He Mode (same cell conditions)

2E5cps

47

93

94

Gillson, Tanner, Douglas

48

95

Co+

Trajectories

80% Ar+

20% O+

80% Ar+

19% O+

1% U+

96IONS IN ARGON FLOW

ICP

SAMPLER

SKIMMER

SHOCK WAVES

49

97IONS ENTRAINED IN Ar FLOWACCELERATED TO SAME VELOCITY AS Ar

AVG. KE OF Ar = AVG. KE IN ICP = 2.5 kT gas

= 0.5 mArvAr2

ALL IONS (i) ACHIEVE SAME VELOCITYvi = vAr

KE i = 0.5 mivi2

IONS OF DIFFERENT MASSHAVE DIFFERENT KINETIC ENERGIES

98ION ENERGY MEASUREMENTSTOPPING POTENTIAL ON QUAD

50

99

ION ENERGY vs m/zM

AX

. IO

N K

E (

eV)

m/z

100Winge, ICP-AES, An Atlas of Spectral Lines

51

101

STRONGEST LINES FROM GIVEN ELEMENT?

1. DOMINANT IONIZATION STAGE (neutral atom or +1 ion)

2. RESONANCE LINES (involve ground state) (esp. absorption!)

3. UPPER LEVEL CORRESPONDS TO LOWEST ENERGY ALLOWED TRANSITIONTO GROUND STATE

Some elements only a few strong lines (Ca, Mg)Other elements many lines (Fe, U)

102

52

103

PARTICLE SIZE EFFECTS IN LASER ABLATION

GÜNTHER & GUILLONGJAAS 2002, 17, 831

AESCHLIMAN et al.JAAS 2003, 18, 1008

104SINGLE SPOT ABLATION

53

105

106

54

107

108

Calibration of LA-ICP-MS with Dried Solution Aerosols

• Simultaneous introduction of particles from a LA cell and desolvated aerosol particles from a micro-flow nebulizer

Stotal = Ssolid + Ssolution

= RX,solid TLAt[X] solid + RX,soln VTneb[X] soln

RX isotope-specific response factor (signal/ng X)TLA transport from LA cell (ng solid/s)t time of ablation transient (s)[X] solid concentration of isotope in solid (ng X/ng solid)V volume of solution injected to ICP (L)Tneb nebulizer efficiency[X] soln isotopic concentration in solution standard (ng X/L)

55

109SPACE CHARGE EFFECTS

OLIVARES & HOUK, ANAL. CHEM. 1985, 57, 2674.

GILLSON et al, ANAL. CHEM. 1988, 60, 1472.

TANNER, SPECTROCHIM. ACTA B 1992, 47B, 809.

PLASMA SOURCE MASS SPECTROMETRY, DEVELOPMENTS & APPLICATIONS, Holland & Tanner, Eds., Royal Society, Cambridge, 1997.

110EXPECT SPACE CHARGE PROBLEM WHEN:

Imax (µA) > 0.9(z/m)1/2(D/L)2V3/2

Imax is current of major bkg. ions

m/z rel. to 12C = 12 V in volts

FOR ICP-MS

Imax ~ 0.4 µA

Actual Imax ~ 1019 atoms/s (nions/natoms)

~ 1019 (1015/1018) ~ 1.5 mA !!

56

111EINZEL LENS – EFFECT OF SPACE CHARGE

BEAMCURRENT

0

1 µA

112

57

113OVERALL EFFICIENCY

1e5 ATOMSINTO ICP

1e5 IONSINTO SAMPLER

1e3 IONSTHRU SKIMMER

1 IONTO DETECTOR!

114

58

115

MATRIX EFFECTS

116

59

117DVS CY-TOFICP-TOFMS

118SURFACE MARKERS IN LEUKEMIA CELL LINES

60

119

120

61

1211 ppb V, Cr, Mn, Ni, Co, Cu, Zn, As500 ppm each C, Na, S, Cl, Ca

122ION EXTRACTION

FUNDAMENTAL ASPECTS OF ION EXTRACTION IN ICP-MSHOUK & NIU, SPECTROCHIM. ACTA B 1996, 51, 779.

GAS DYNAMICS OF THE ICP-MS INTERFACEDOUGLAS & FRENCH, JAAS 1988, 3, 743.

IMPROVED INTERFACE FOR ICP-MSDOUGLAS & FRENCH, SPECTROCHIM. ACTA B 1986, 41, 197.

ION EXTRACTION IN ICP-MSOLIVARES & HOUK, ANAL. CHEM. 1985, 57, 2674.

CHAP. IN MONTASER ICP-MS BOOK

RECENT PAPERS BY PAUL FARNSWORTHBRIGHAM YOUNG UNIV.

62

123

124