Slide 1 Vasiliy V Rosen, M Sc , ZBM Analytical Laboratory www rosen r8 org 2011 ATOMIC SPECTROSCOPY Absorption Spectroscopy AAS Emission Spectroscopy FES, ICP AES(OES) Mass Spectrometry ATOMIC SPECTRO.
Vasiliy V Rosen, M.Sc., ZBM Analytical Laboratory www.rosen.r8.org 2011 ATOMIC SPECTROSCOPY Absorption Spectroscopy: Emission Spectroscopy: AAS FES, ICP-AES(OES) Mass Spectrometry ATOMIC SPECTROSCOPY Ion Emission Atom Emission E – energy difference between two levels; h – Plank’s constant, 6.626068 × 10-34 m2kg/s; c – speed of light, 299 792 458 m/s; λ – wavelenght, nm After Boss C.B and Freden K.J Concepts, Instrumentation and Techniques in Inductively Coupled Plasma Optical Emission Spectrometry 1997 ATOMIC SPECTROSCOPY Nebulizer converts the solution into a spray Flame (or Plasma) causes the solvent to evaporate, leaving dry aerosol particles, then volatilizes the particles, producing atomic, molecular and ionic species After Skoog D Fundamentals of Analytical Chemistry, 2004, p 844 FLAME EMISSION SPECTROSCOPY (FES) ❑ Propane-butane flame ( 2000 – 3000 º C); ❑ Optical filter is used to monitor for the selected emission wavelength produced by the analyte; ❑ Suitable for elements with low excitation energy (Na, K, Li, Rb and Ca) FLAME EMISSION SPECTROSCOPY (FES) Optic Filter Flame Data Display Nebulizer Flame Photometer M-410 (Sherwood Scientific, UK) ATOMIC ABSORPTION SPECTROSCOPY (AAS) ❑ Gases mixture flame (1800 – 4500 º C): air-propane, air-acetylene etc ; ❑ Atomic absorption spectrometry quantifies the absorption of ground state atoms in the gaseous state ; ❑ The atoms absorb ultraviolet or visible light and make transitions to higher electronic energy levels The analyte concentration is determined from the amount of absorption ATOMIC ABSORPTION SPECTROSCOPY (AAS) Elements detectable by AA are highlighted in pink ATOMIC ABSORPTION SPECTROSCOPY (AAS) Operation principle of AAS ❑Light source – hollow cathode lamp Each element has its own unique lamp ❑Atomic cell – flame (gas mixture) or graphite furnance (accepts solutions, slurries, or even solids) ❑Detector – photomultiplier After G.Ma and G.W Gonzales, http://www.cee.vt.edu ATOMIC ABSORPTION SPECTROSCOPY (AAS) ICP-AES SPECTROMETER ARCOS Schematic diagram of the processes in the ICP After Spectro Gmbh, Germany ICP SPECTROMETER Main Systems ❑Sample Introduction System: to deliver the sample solution to the plasma Consists of pump, nebulizer and spray chamber ❑ Plasma: to generate the signal Plasma is forming in the torch from gas argon ❑ Optics: to measure the signal ❑Computer with appropriate software: for controlling the instrument and measuring process ICP-AES: SAMPLE INTRODUCTION SYSTEM Torch with Plasma Nebulizer (cross-flow) Spray Chamber To Waste Sample Solution Entrance Argon Supply ICP-AES: PLASMA A plasma is a hot, partially ionized Inductively Coupled Plasma Source gas It contains relatively high concentrations of ions and electrons Argon ions, once formed in a plasma, are capable of absorbing sufficient power from an external source to maintain the temperature at a level at which further ionization sustains the plasma indefinitely The plasma temperature is about 10 000 K After Manning T.J and Grow W.P., 1997 ICP-AES: PLASMA Inductively Coupled Plasma Source ICP-AES: RADIAL (SOP) AND AXIAL (EOP) SOP: Side-on-Plasma EOP: End-on-Plasma ❑ more suitable for hard matrices (concentrated samples); ❑ more suitable for light matrices; ❑ alkali metals (Na, K, Li) calibration is more linear; ❑ alkali metals (Na, K, Li) calibration is less linear; ❑ less spectral interferences; ❑ more spectral interferences; ❑lower sensitivity (Limit-of-Detection is higher); ❑higher sensitivity (Limit-of-Detection is lower); ICP-AES: RADIAL (SOP) AND AXIAL (EOP) After Spectro Gmbh, Germany ICP-AES: OPTICS After Spectro Gmbh, Germany ICP-AES: SAMPLE PREPARATION Microwave-assisted Digestion Hot Plate Digestion Block Most samples have to be prepared for analysis by ICP Solid samples are solubilized Organic matter is "mineralized" i.e converted to inorganic compounds ICP-AES: CALIBRATION CURVE ICP-AES: SPECTRAL INTERFERENCES Au (gold) peak on 242.795 nm ICP-AES: SPECTRAL INTERFERENCES Au (gold) peak on 242.795 nm is Au (gold) peak on 267.595 nm is free interfered by Mn 242.794 nm of Mn interference! ICP-AES, FES AND AAS: APPLICATION ❑ Clinical Analysis: metals in biological fluids (blood, urine); ❑ Environmental Analysis: trace metals and other elements in waters, soils, plants, composts and sludges; ❑ Pharmaceuticals: traces of catalysts used; traces of poison metals (Cd, Pb etc); ❑ Industry: trace metal analysis in raw materials; noble metals determination ❑ Forensic science: gunshot powder residue analysis, toxicological examination ( e.g., thallium (Tl) determination) REFERENCES ❑Boss, C.B and Freden, K.J Concepts, Instrumentation and Techniques in Inductively Coupled Plasma Optical Emission Spectrometry 1997 ❑Skoog, D Fundamentals of Analytical Chemistry, 2004 ❑Ma, G and Gonzales, G.B Flame Atomic Absorption Spectrometry http://www.cee.vt.edu ❑Manning T.J and Grow W.P Inductively Coupled Plasma Atomic Emission Spectrometry The Chemical Educator, v.1 N 1997 ❑ Lecture by Dr Mordechay Shoenfeld, “ICP-AES”, Course 71106, Faculty of Agriculture, HUJI 2010 ... SPECTROSCOPY (AAS) ATOMIC EMISSION SPECTROSCOPY ICP-AES Inductively Coupled Plasma - Atomic Emission Spectrometry ICP-AES Basics ? ?Atomic emission spectroscopy measures the intensity of light emitted... from the amount of absorption ATOMIC ABSORPTION SPECTROSCOPY (AAS) Elements detectable by AA are highlighted in pink ATOMIC ABSORPTION SPECTROSCOPY (AAS) Operation principle of AAS ❑Light source... Scientific, UK) ATOMIC ABSORPTION SPECTROSCOPY (AAS) ❑ Gases mixture flame (1800 – 4500 º C): air-propane, air-acetylene etc ; ❑ Atomic absorption spectrometry quantifies the absorption of ground state