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contrAA ® - A Revolution in Spectroscopy Basics and Applications of High-Resolution Continuum Source AAS
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Methods for element analysis contrAA ® - A Revolution in Spectroscopy2 AAS – a well established method for more than 50 years BUT !! Simplicity Less interferences Robustness Low purchase cost Low operation cost Single element method Specific HCLs required Unprofitable for many elements Limitation in background correction
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New instrument development needs motivation contrAA ® - A Revolution in Spectroscopy3 AAS goes multielement!
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LS AAS Cx CuPb Fe Cd Ni Zn Single element method New instrument development needs motivation: We expect fast results 4contrAA ® - A Revolution in Spectroscopy
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Real multielement Analysis CS AAS Sequential multi element analysis Cu, Pb, Fe, Cd, Ni, Zn… New instrument development needs motivation: We expect fast results 5contrAA ® - A Revolution in Spectroscopy
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New instrument development needs motivation contrAA ® - A Revolution in Spectroscopy6 In case of a spectral interference, we can see only the result, but not the reason – therefore the optimization of method parameters to avoid the spectral interferences is difficult. Background correction failed, but why??? We need more information!
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Key components of HR-CS AAS contrAA ® - A Revolution in Spectroscopy7 HR-CS AASLS-AAS Radiation source Xenon – short arc lampHCL, EDL, boosted HCL Atomizer Identical atomizer for flame and graphite technique Monochromator High resolution >1:140000Low resolution Detector CCD array detectorSingle spot detector (PMT) Software ASpectCS ® WinAAS ®
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Optical set up CS AAS Furnace Echelle grating Flame Arc lamp High Resolution Monochromator prism CCD detector ISAS Berlin Low focal length: f 400 mm High spectral resolution: / Δ > 145 000 8contrAA ® - A Revolution in Spectroscopy
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Radiation source contrAA ® - A Revolution in Spectroscopy9 LS AAS Hollow cathode lamp (HCL) line radiator Cathode contains the element to be analyzed Xenon short arc lamp continuum radiator Covers whole wave length range 185 – 900 nm Determination of more than 67 elements with one lamp only HR-CS AAS
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Radiation source contrAA ® - A Revolution in Spectroscopy10 Different radiation sources in comparison A Xenon-short arc lamp, XBO 301, 300 W, (GLE Berlin), „Hot - Spot“ - Mode B Xenon lamp, L 2479, 300 W, (HAMAMATSU), diffuse mode C D2 - Lamp, MDO 620, 30 W, (HERAEUS) Source: „High-resolution continuum source AAS“ Welz,Becker-Roß,Florek,Heitmann Ag Au Pb Cd Pb Zn As
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Atomizer in HR-CS AAS contrAA ® - A Revolution in Spectroscopy11 Graphite furnace atomizer Quartz cell atomizer Flame atomizer
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Double Echelle Monochromator contrAA ® - A Revolution in Spectroscopy12 2 6 5 4 3 1 2 Source: ISAS Berlin 1: entrance slit (fixed) 2: off-axis parabolic mirror 3: prism in Littrow- position 4: intermediate slit (variable) 5: Echelle- grating in Littrow- position 6: CCD – array detector
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LS AAS Emission scan Mn – Triplet: 279.4817 nm 279.8269 nm 280.1085 nm Monochromator resolution LS AAS vers. HR-CS AAS CS AAS Absorption spectra Resolution factor 100 better than LS AAS !!! 13contrAA ® - A Revolution in Spectroscopy
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AnalyteWavelength (nm)Disturbing elements Wavelength (nm) -Difference (pm) Se196.03Fe196.06030 As193.70Fe193.67030 Zn213.856Fe213.8593 Cd228.80As Fe 228.810 228.720 10 80 Ni232.003Fe232.03633 Sn224.605Pb Fe 224.690 224.565 85 40 Mn279.48Fe279.47010 Cu324.75Fe324.60015 Al396.15Fe396.11040 High Resolution – spectral interferences 14contrAA ® - A Revolution in Spectroscopy
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CCD Detector contrAA ® - A Revolution in Spectroscopy15 New detection technology Detector “Pixels” are illuminated and read out simultaneously and independently. 200 Pixels are used analytically 200 independent detectors ! 3 Pixels for AA measurement - and the others???
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Corrections contrAA ® - A Revolution in Spectroscopy16 Type of interferenceLS-AASHR-CS AAS Lamp intensity driftOptical double beam sequential Reference pixels simultaneous Thermal emissionLamp modulation sequential Reference pixels simultaneous Non specific absorptionBG correction sequential Reference pixels reference spectrum simultaneous
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Corrections contrAA ® - A Revolution in Spectroscopy17 In HR-CS AAS we have a Third Dimension, i.e. we can see a lot more ! We can see the spectral interference We can avoid the spectral interference And we have much better ways to correct for spectral interferences
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Background correction and resolution contrAA ® - A Revolution in Spectroscopy18 V 318.341 V 318.540 Ni 318.437 Fe 318.490
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Corrections of discontinuous events contrAA ® - A Revolution in Spectroscopy19 OH, NO, CN are natural constituents of flame gases NO, PO, SiO, CS etc. might be generated in the presence of high matrix concentration Neither the D2 nor the Smith-Hieftje system can correct for this background, the Zeeman system can only correct if the background is not affected by the magnetic field ! In HR-CS AAS we can measure and store a reference spectrum that can be subtracted from the sample spectrum using a least-squares algorithm Diatomic molecules with rotational fine structure
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A Short Glance on Correction Models “Least Squares Background Correction ” 20contrAA ® - A Revolution in Spectroscopy
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NO- Structure on Zn- line 213.857 nm Corrections of discontinuous events - Recording of reference spectra blank: 1% HNO 3 1% HNO 3 + 0.05 mg/L Zn 21contrAA ® - A Revolution in Spectroscopy
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Correction of NO structure at 213.857 nm Zn- line NO structures corrected Zn absorption spectra Corrections of discontinuous events - Recording of reference spectra 22contrAA ® - A Revolution in Spectroscopy
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23 Quality is the difference Quality is the difference
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contrAA ® - A Revolution in Spectroscopy24 Thank you for your attention!
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