ICP AES overview-Nipa 25.01.2023.pptx

Estimation of heavy metals and trace elements by inductively couple plasma-atomic emission spectrometer

1. Q UANTITATIV E ESTIMATION OF TRACE ELEMENTS BY INDUCTIVELY COUPLED PLASMA- ATOMIC EMISSION SPECTROSCOPY( ICP-AES) Presenter Dr. Nipa Mendapara Junior Resident Department of Pharmacology AIIMS New Delhi

2. ICP-AES USE: U sed for the determination of ppm levels of metals in liquid samples It is widely used to analyze liquid samples as well as substances that are easily dissolved or digested into liquid form Common sample types analyzed by ICP include trace elements in polymers, wear metals in oils, and numerous catalysts 2

3. Trace elements https://www.sciencelearn.org.nz/images/2143-elements-in-the-human-body 3

4. Clinical importance of trace elements E ssential trace elements are usually associated with an enzyme ( metalloenzyme) or protein ( metalloprotein ) as an essential component or cofactor. Deficiencies typically impair one or more biochemical functions E xcess concentrations are associated with at least some degree of toxicity. 4

5. Photon Energy Absorbed Energy Emitted Atomic Absorption Spectrometer Atomic Emission Spectrometer E= hc / λ Why does the elements emit or absorb a specific radiation? 5

6. Atomic Absorption Light of specific wavelength from Hollow Cathode Lamp (HCL) Atomic Emission Light and heat energy from high intensity source (flame or plasma) Mass Spectrometry Light and heat energy from high intensity source (plasma) Light of specific characteristic wavelength is absorbed by promoting an electron to a higher energy level (excitation) Light absorbed is proportional to elemental concentration High energy (light and heat) promotes an electron to a higher energy level (excitation). Electron falls back and emits light at characteristic wavelength. Light emission is proportional to elemental concentration High energy (light and heat) ejects electron from shell (ionization). Result is free electron and atom with positive charge (ion) Ions are extracted and measured directly in mass spectrometer METHODS 6

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9. WHICH METHOD TO USE AND WHEN? AAS MS 9

10. ICP-Mass spectrometry (MS) It has multi-element capability Liquid samples are first nebulized in the sample introduction system , creating a fine aerosol that is subsequently transferred to the argon plasma High-temperature plasma atomizes and ionizes the sample, generating ions which are then extracted through the interface region and into a set of electrostatic lenses called the ion optics. 10

11. Continue.. The ion optics focuses and guides the ion beam into the quadrupole mass analyzer. The mass analyzer separates ions according to their mass-charge ratio (m/z), and these ions are measured at the detector. 11

12. ICP-MS 12

13. Difference between AES and MS ICP-AES Provides higher detection limit down to ppm or ppb Detects energy (photons) emitted by the atoms Isotopes compositions can not be detected Less costly compared to MS ICP-MS P rovides a lower detection limit down to ppt ( ng/l) ( highly sensitive) A ble to detect the ions. Then, these ions are sorted on account of their mass.  Possibilities to detect isotope composition of elements i.e. 2 H/ 1 H,  13 C/ 12 C Disadvantages is the occurrence of spectral and non-spectral interferences and the high costs. 13

14. ICP-AES 14

15. ICP-AES for the estimation of heavy metals Model: JY 2000-2 Company: Horiba Jobin Yvon ICP-AES 15

16. ATOMIC EMISSION SPECTROPHOTOMETER The fundamental characteristic of this process is that each element emits energy at specific wavelength peculiar to its atomic structure. The energy transfer for electron when they fall back to ground state is unique to each element as it depends on the electronic configuration of the orbital. The energy transfer is inversely proportional to wavelength of electromagnetic radiation E= hc /n where h is plank’s constant; c is velocity of light and n is the wavelength. Hence, the wavelength of light emitted is also unique! 16

17. Principle Inductively Coupled Plasma-Atomic Emission Spectrometer Atoms of samples are excited by plasma at very high temperature (10000 K) Return to the normal states, emit characteristic photons of energy Electrons of an atom absorb energy and jump to higher energy levels 17

18. PLASMA- It is a conducting gaseous mixture containing a significant concentration of ions and electrons. Arg o n Plasma is commonly used. The temperature of the plasma may be of the order of 5,000 to 10,000 K. 18

19. Working flow of ICP-AES 19

20. 7. As the excited atoms reach the detector they again decay to ground state and emitting a photon 8. This photon is amplified and captured by the detector with charge coupled device (CCD) 1. Plasma Gas flows into the ICP Torch 2. Radiofrequency (RF) Generator coil induces Electromagnetic Potential (40.68 MHz) 3. Ionization of Argon Ar ------> Ar + & e- 4. Resistance of e- to move with the circular magnetic field causes intense heat and generation of Plasma 5. Injection of sample element through the nebulizer 6. Atoms leave the flame towards detector (Axial or Radial) in a excited state Ar Ar Ar Ar 20

21. Components of ICP-AES Sample introduction system Radiofrequency generator Optical system Signal processing system Computer system Inductively coupled plasma source Separation and detection 21

22. 1. Sample Introduction System: Liquid samples are pumped into the nebulizer and sample chamber via a peristaltic pump. Then the samples pass through a nebulizer that creates a fine mist of liquid particles. Larger water droplets condense on the sides of the spray chamber and are removed via the drain, while finer water droplets move with the argon flow and enter the plasma. Nebulizers help ensure that the sample enters into the plasma at a uniform flow rate and specific droplet size. Droplets that are great than 5 µm in diameter are likely to interfere with plasma stability. 22

23. 2. Radiofrequency Generator: Creates an oscillating magnetic field around the torch that results in ohmic ( inductive ) heating of the charged gases at the end of the torch: Sustains plasma Solid-state semiconductor generators (commonly used), where circuit consists of Capacitor: Stores a high electrical charge (thus requiring the 220-240 V electrical power requirements) Inductor coil: Deliver the oscillating current to the torch and generate the magnetic field around the torch 23

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25. Torch The plasma is formed in the end of a set of three concentric quartz tubes , collectively referred to as the torch Argon gas flows through all three tubes The inner tube is called the injector, and contains the sample aerosol in a stream of argon which delivers the sample to the plasma Concentric to this tube is a tangential flow of argon called the auxiliary gas, which forms the plasma The outer tube contains a flow of argon which serves as a cooling layer to prevent the torch from melting 25

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27. Plasma: Partially ionized gas which is electrically neutral (cations and electrons) 27

28. View of the detection Depending on the concentration of analytes in a given sample, the analyst may choose to monitor the emissions from the Radial view: for higher concentrations Axial view: for lower concentration 28

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30. Types of spectrometers Three categories of detection are available for analysing the emitted photons: Sequential Simultaneous multi-channel Fourier transform systems 30

31. In both, all wavelengths enter a monochromator where they are dispersed by prisms and/or grating monochromators and are then transmitted to the detector SEQUENTIAL SIMULTANEOUS MULTI-CHANNEL 31

32. Types of spectrometers Sequential : less expensive and more flexible They include a single photomultiplier tube and movable gratings to select wavelength in sequential orders Direct/ simultaneous : f aster, more precise, and more accurate All elements (up to 60) are determined simultaneously by increasing the analytical speed Radiations from the plasma enter through single slits and are dispersed by a concave reflection grating Then these wavelengths reach a series of exit slits which isolate specific wavelengths for specific elements https://psiberg.com/atomic-emission-spectroscopy/ 32

33. Fourier transform systems No slits or monochromators are required, and this creates better detector limits because more intense radiation reaches the detector. Fourier transform systems also have higher spectral resolution (and thus have fewer spectral interferences) and can simultaneous monitor all wavelengths for longer times. 33

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35. APPLICATIONS OF ICP-AES 35

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39. Research studies undertaken in our Department 39

40. Other Examples of ICP AES studies S S , Ss A, S SB, Hk V, Pv M. Determination of the bioavailability of zinc oxide nanoparticles using ICP-AES and associated toxicity. Colloids Surf B Biointerfaces . 2020 Apr;188:110767. Zhang Y, Ge S, Yang Z, Dong C. Heavy metals analysis in chalk sticks based on ICP-AES and their associated health risk. Environ Sci Pollut Res Int. 2020 Oct;27(30):37887-37893.  Reproductive toxicity of lead, cadmium and phthalate exposure in men. Pant N, Kumar G, Upadhyay AD, Patel DK, Gupta YK, Chaturvedi PK. Environ Sci Pollut Res Int. 2014 Sep;21(18):11066-74 Monitoring of mercury, arsenic, cadmium and lead in Ayurvedic formulations marketed in Delhi by flame AAS and confirmation by ICP-MC. Kumar G, Gupta YK.Food Addit Contam Part B Surveill . 2012;5(2):140-4. Semen quality of environmentally exposed human population: the toxicological consequence. Pant N, Pant AB, Chaturvedi PK, Shukla M, Mathur N, Gupta YK, Saxena DK. Environ Sci Pollut Res Int. 2013 Nov;20(11):8274-81 Dark colored semen in non obstructive azoospermia : a report of four cases. Halder A, Jain M, Chaudhary I, Kumar G, Das T, Gupta YK. Andrologia . 2014 Apr;46(3):316-21 40

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