CMIS-1Comment mesurer les concentrations en éléments traces, ultra-traces… isotopes ?InductivelyCoupledPlasma Mass Spectrometry: ICP-MS

1 Dr Yann Sivry - sivry@ipgp.fr

Aquatic Geochemistry Team - Institut de Physique du Globe de Paris & Université Paris 7 UMR CNRS 7154

1, Rue Jussieu 75238 Paris cedex 05 Tel : +33 (0) 1 83 95 74 55 Fax : +33 (0) 1 83 95 77 08

e-mail : sivry@ipgp.fr

CMIS-1

Comment mesurer les concentrations en éléments traces, ultra- traces… isotopes ?

Inductively Coupled Plasma Mass Spectrometry : ICP-MS

Université Paris Diderot LiPAC

Novembre 2020

Dr Yann Sivry - sivry@ipgp.fr

CMIS-1

Comment mesurer les concentrations en éléments traces, ultra- traces… isotopes ?

Inductively Coupled Plasma Mass Spectrometry : ICP-MS

3

Definitions

 Spectroscopy = general term used to describe analytical methods based on absoprtion, emission or fluorescence of some molecules (Receptor = eye)

 Spectrometry = methods using a dispersive element (Receptor is not the eye)

 Spectroscopic methods = methods based on interaction between electromagnetic radiations and matter

Periodic table of elements - Mendeleïev

• Emission: ICP-AES, DP-AES, flame

• Absorption: flame, oven, atomic vapor

• Fluorescence: atomic, X (XRF)

• Mass (+ isotopes): ICP-MS, étincelle, TOF-SIMS

• Core: INAA (neutronic activation)

Elemental analysis

7

Analytical range(s)

Reminds on prefixes used

9

Introduction: Mass Spectrometry

 Analytical tools/methods allowing the detection and quantification of almost all the periodic table elements

This involves free atomes at vapor state (no more included in a molecule)

 Thus, the machine will:

o produce atomic vapor from the sample

o induce the molecule destruction = no more information on the nature of initial molecules (except if coupling with speciation technique)

 Possible to dose simultaneously all the species of a given element

Mass spectrometry

Measurement of the mass/charge ratio of ionized molecules

Major steps of the measurement:

1) Ionization and extraction of the sampling gas

2) Separation of charged molecules as a function of the m/q ratio:

- Increasing the velocity (v) in an electric potential (U) - Separating in a magnetic field (B)

3) Collection of the charged molecules and creation of an electric current which is amplified then converted into high voltage

Introduction: Mass Spectrometry

11

Sample introduction: nebulisation

Cyclonic chamber Scott chamber

Nebulisation/Spray chambers

• Nebulizer reproducibility is essential: flow and size distribution of droplets. Ultrasonic nebulizer is not dependent on pneumatic variations nor turbulances: it will ensure the best reproducibility.

• Nebulization variability will induce analytical variability.

The internal standard method is the best method to correct this bias as the element added is measured exactly simultaneously to the analyte.

13

Nebulisation efficiency

• Induced current (ICP) or microwave (MW).

• Coupling Plasma-Generator with a spire from 2 to 4 rolls.

• High frequencey (MHz), high power (kW).

• Plasma (ionized gas) from 6000K to 12000K.

Warming system: the plasma torch

15

Warming system: the plasma torch

Warming system: the plasma torch

Inductively Coupled Plasma

= ion source

Mass Spectrometry

= detection

17

ICP-MS

• Ar, Ar ⁺ , e ^- , atoms and ions.

• If T increases, ionization increases

• Saha law:

Oxyde rate: M

+ O = MO

Nebulization

Position of the flame

ICP-MS: Plasma Chemistry

19

ICP-MS – The Interface: Extraction

ICP-MS: Separation between ions and neutrals/photons

1/ Quadrupole ion deflector (Perkin)

21

ICP-MS: Separation between ions and neutrals/photons

2/ Ion transfer optics (Thermo)

Tiges métalliques Détecteur

Tension AC + DC Faisceau ionique

issue de la source

m/z

ICP-MS: Mass Filter

1/ Quadrupolar (Q-ICP-MS)

23

ICP-MS: Mass Filter

2/ Magnetic sector field (HR-ICP-MS)

ICP-MS: detection system

1/ Discrete Dynode Detector

ICP-MS: detection system

2/ Faraday cup

ICP-MS: Global Scheme

1/ The Nexion Triple-Q-ICP-MS (Perkin)

27

ICP-MS: Global Scheme

2/ The X-Series Q-ICP-MS (Agilent)

ICP-MS: Global Scheme

3/ The Element II HR-ICP-MS (Thermo)

ICP-MS: Global Scheme

4/ The Neptune Multi-Collector-ICP-MS (Thermo)

2) Separation of charged molecules as a function of the m/q ratio:

- Increasing the velocity (v)

- Separating in a magnetic field (B)

3) Collection of the charged molecules and creation of an electric current which

ICP-MS: Global Scheme

ICP-MS: Global Scheme

General scheme of the Nier’s mass spectrometer

ICP-MS: Global Scheme

33

TIMS : Thermal Ionization Mass Spectrometry

MC-ICP-MS: Multi-Collector Inductively Coupled Plasma Mass Spectrometry

Interférences isobariques,

polyatomiques

The atomic core is composed by 2 types of particles: protons and neutrons, also

called nucleons

A X

Z

Z = nb of protons in the core N = nb of neutrons in the core

Z is also equal to the nb of electrons (except for ions) since neutrons are not charged

A = atomic mass nb = N + Z

Reminds: the internal structure of atoms

1 uma = 12 10

kg / 12. Na = 1,66055 10

kg Na = Avogadro nb = 6,022098 10

atoms

1 proton = 1.00727647 uma 1 neutron = 1.008665 uma

Same value for Z (protons) not for A Two isotopes have different neutrons

Definition:

1 mole of

C atoms = 12.00000000…g Atomic mass of C :

Reminds: Isotopes

Reminds: Which isotopes (elements) are analyzed by ICP-MS?

39

Z (atomic nb) = nbof protons

Phosphorus isotopes

12 C

127N ¹³₇N

13 C

11 C

Reminds: the nuclides table

First step: Chemical preparation of samples

CRUSHING < 60 µm EVAPORATION

AQUEOUS SOLUTION  ACID DIGESTION in a clean room

Isolation of the target element (Sr, Zn…)  CHEMICAL SEPARATION in a clean room

ISOTOPIC COMPOSITION measurement by mass spectrometry

SAMPLING

0 5 10 15 20 25 30

142 143 144 145 146 147 148 149 150 151 152 153 154

masses

Abundance(%)

Samarium (Sm) Néodyme (Nd)

Why do we need to purify the element?

Isobars may disturb the measurement of ¹⁴³Nd/¹⁴⁴Nd!

The Rubidium – Strontium couple

0 10 20 30 40 50 60 70 80 90

84Sr ⁸⁶Sr ⁸⁷Sr ⁸⁸Sr

Sr isotopes

%

0,56%

9,86% 7,00%

82,58%

Natural abundances (%)

0 10 20 30 40 50 60 70 80

85Rb ⁸⁷Rb

Isotopes du Rb

%

72,165%

27,835%

Natural abundances (%)

Isobaric interferences

Polyatomic interferences

Work in a clean room

Chemical separation

Cationic exchange resin:

This reaction is associated to a value “K” which is resin, acid and ion dependent.

M⁺+ H-R  M-R + H⁺

Elements et isotopes

Isotope Masse (a.m.u.) Abondance (%) Isotope Masse (a.m.u.) Abondance (%)

1H 1.007825 99.985 ³¹P 30.973763 100

2H (D) 2.014102 0.015 ³²S 31.972072 95.02

12C 12.000000 98.90 ³³S 32.971459 0.75

13C 13.003355 1.10 ³⁴S 33.967868 4.21

14N 14.003074 99.634 ³⁶S 35.967079 0.02

15N 15.000109 0.366 ³⁵Cl 34.968853 75.77

16O 15.994915 99.762 ³⁷Cl 36.965903 24.23

17O 16.999131 0.038 ⁷⁹Br 78.918336 50.69

18O 17.999159 0.200 ⁸¹Br 80.916290 49.31

19F 18.998403 100 ¹²⁷I 126.904477 100

Masse

O proche masse de

S ou

S

comme

O

Interférences polyatomiques

• Plasma: O, H, Cl, C, Ar, O ⁺ , Ar ⁺ , Cl ⁺ , C ⁺ ,

…..

• Formation de tous les ions bi moléculaires possibles, quelques tri.

– Ar: 40, 36, 38 – O: 16, 18, 17 – C: 12, 13

– N: 14, 15

• ArC ⁺ , ArO ⁺ , ArO ₂ ⁺ , ….

47

Interférences courantes

49

Calcul de la résolution nécessaire ?

51

Isotope Ion interférant Résolution

56

Fe

Ar

0 2500

75

As

Ar

Cl 7800

80

Se

Ar

Ar 9700

40

Ca

Ar 193000

Exemples d'interférences

Isotope Ion interférant Résolution

56

Fe

Ar

0 2500

75

As

Ar

Cl 7800

80

Se

Ar

Ar 9700

40

Ca

Ar 193000

Interférences isobariques

53

Interférences isobariques

Exercice : Si 10^6 coups/ppb quel que soit l’élément

55

57

59

61

63

Q Resolution M/M = 300

65

67

69

71

73

75

77

79

81

Exemples de prix (Perkin)

83