Transcript Product Brochure
contrAA
®
A Revolution in Spectroscopy
Basics and Applications of High-Resolution Continuum Source AAS
Methods for element analysis AAS – a well established method for more than 50 years
Simplicity Less interferences Robustness Low purchase cost Low operation cost
BUT !!
Single element method Specific HCLs required Unprofitable for many elements Limitation in background correction contrAA ® - A Revolution in Spectroscopy 2
New instrument development needs motivation
AAS goes multielement!
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New instrument development needs motivation: We expect fast results LS AAS Cx
Single element method contrAA ® - A Revolution in Spectroscopy Cu Pb Fe Cd Ni Zn 4
New instrument development needs motivation: We expect fast results Real multielement Analysis CS AAS
Cu, Pb, Fe, Cd, Ni, Zn… Sequential multi element analysis contrAA ® - A Revolution in Spectroscopy 5
New instrument development needs motivation We need more information!
Background correction failed, but why???
In case of a spectral interference, we can see reason only the result , but not the – therefore the optimization of method parameters to avoid the spectral interferences is difficult.
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Key components of HR-CS AAS HR-CS AAS LS-AAS Radiation source
Xenon – short arc lamp
Atomizer
HCL, EDL, boosted HCL Identical atomizer for flame and graphite technique
Monochromator
Low resolution High resolution >1:140000
Detector
CCD array detector
Software
ASpectCS ® Single spot detector (PMT) WinAAS ® contrAA ® - A Revolution in Spectroscopy 7
Optical set up CS AAS
Furnace Flame CCD detector Echelle grating Arc lamp prism High Resolution Monochromator
ISAS Berlin High spectral resolution: / Δ > 145 000 contrAA ® - A Revolution in Spectroscopy Low focal length: f 400 mm 8
Radiation source
LS AAS Hollow cathode lamp (HCL) line radiator
Cathode contains the element to be analyzed
HR-CS AAS Xenon short arc lamp continuum radiator
Covers whole wave length range 185 – 900 nm Determination of more than 67 elements with one lamp only contrAA ® - A Revolution in Spectroscopy 9
Radiation source Different radiation sources in comparison
100 10 1
Ag
0.1
Pb
0.01
As Zn
1E-3
Pb Cd Au
200 250 300 Wavelength [nm] 350 A B C Source: „High-resolution continuum source AAS“ Welz,Becker-Roß,Florek,Heitmann 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) contrAA ® - A Revolution in Spectroscopy 400 10
Atomizer in HR-CS AAS
Flame atomizer Graphite furnace atomizer Quartz cell atomizer contrAA ® - A Revolution in Spectroscopy 11
Double Echelle Monochromator
6 1 4 3 5 2 Source: ISAS Berlin contrAA ® - A Revolution in Spectroscopy 2 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 12
Monochromator resolution LS AAS vers. HR-CS AAS LS AAS Emission scan
Mn – Triplet: 279.4817 nm 279.8269 nm 280.1085 nm
CS AAS Absorption spectra
Resolution factor
100
better than LS AAS !!!
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High Resolution – spectral interferences
Analyte Wavelength (nm) Disturbing elements Wavelength (nm) Se As Zn Cd Ni Sn Mn Cu Al 196.03
193.70
213.856
228.80
232.003
224.605
279.48
324.75
396.15
Fe Fe Fe As Fe Fe Pb Fe Fe Fe Fe 196.060
193.670
213.859
228.810
228.720
232.036
224.690
224.565
279.470
324.600
396.110
contrAA ® - A Revolution in Spectroscopy -Difference (pm) 30 30 3 10 80 33 85 40 10 15 40 14
CCD Detector New detection technology
contrAA ® - A Revolution in Spectroscopy 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 Type of interference
Lamp intensity drift Thermal emission Non specific absorption
LS-AAS HR-CS AAS
Optical double beam sequential Reference pixels simultaneous Lamp modulation sequential Reference pixels simultaneous BG correction sequential Reference pixels reference spectrum simultaneous contrAA ® - A Revolution in Spectroscopy 16
Corrections
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 contrAA ® - A Revolution in Spectroscopy 17
Background correction and resolution
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Corrections of discontinuous events Diatomic molecules with rotational fine structure
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 contrAA ® - A Revolution in Spectroscopy 19
A Short Glance on Correction Models “Least Squares Background Correction
”
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Corrections of discontinuous events - Recording of reference spectra
NO- Structure on Zn- line 213.857 nm
blank: 1% HNO 3
contrAA ® - A Revolution in Spectroscopy
1% HNO 3 + 0.05 mg/L Zn
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Corrections of discontinuous events - Recording of reference spectra
Correction of NO structure at 213.857 nm Zn- line NO structures corrected Zn absorption spectra contrAA ® - A Revolution in Spectroscopy 22
contrAA ® - A Revolution in Spectroscopy
contrAA ® - A Revolution in Spectroscopy
Thank you for your attention!
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