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DRC
Dynamic Reaction Cell
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PGE
Platinum Group Elements
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Higher temperatures produce (more/less) emission lines
more (see slide 8 of INST395 Emission Spectrometry powerpoint)
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Line spectra are produced by __ while band spectra are produced by ___
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Name two setups for ICP detection. Which is faster?
- Sequential
- Simultaneous (faster)
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CCD (or CID) What is it?
- Charge Couple Device
- Charge Injection Device
- A solid state simultaneous detector
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What type of ICP detector requires mapping?
CCD/CID (solid state computer chip detector)
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What are the two torch positions for ICP?
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Which torch configuration has less interferences?
Radial
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Which torch configuration can giver lower detection limits but is effected by dirty samples?
Axial
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What are the zones in a plasma? Which are of interest to detect?
- Desolvation
- Atomization (what you want to detect)
- Ionization
- Recombination
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What must you do to the optics chamber if you want to detect UV wavelengths? Why?
Purge the chamber from oxygen, since it absorbs UV light
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Ultrasonic nebulization can give ___ detection limits because ___ droplets make it to the plasma
- Lower
- More (around twice as many)
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Which nebulization technique is better for higher dissolved solids?
Ultrasonic
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GF-ICP or ETV-ICP
- Graphite Furnace
- Electrothermal Vaporization
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In order to use GF-ICP, the sample must be __
volatile (the entire thing must vaporize for accurate results)
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Name two techniques that allow the direct analysis of solid samples by ICP without dissolving them
- Laser ablation (LA)
- Arc ablation (AA or ARC)
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What are some disadvantages of LA techniques?
- Selection Effects (if parts of the sample are more volatile)
- Samples can't be reflective, transparent or opaque
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To get a more representative analysis using arc or laser ablation, what can you do?
Take readings at multiple spots
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What torch configuration is used for ICP-MS?
Axial
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Disadvantage of ICP-MS
- More finicky (room must be clean to get low LOD)
- Cones at MS interface get dirty easily and require cleaning
- Expensive
- Isobaric interferences
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Are the emitted photons from the ICP used in ICP-MS?
No. They are re-focussed away from the detector and a shadow stop is also used to prevent them from interfering
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Sample ions enter the MS at __ speed
high (a supersonic jet)
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What was the most common type of ion detector in an ICP-MS? What has it been replaced by?
- channel electron multiplier (CEM)
- Discrete dynode detectors are now used (wider linear dynamic range)
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Do photons produce a signal when they hit the ICP-MS detector?
Yes, that's why you need a shadow stop to block them from interfering
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Interference that occurs when another species has the same mass as the analyte
Isobaric interference
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Two categories of ICP-MS interferences
- Spectral (isobaric interferences)
- Matrix (change physical properties of fluid or plasma)
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GD-MS
Glow discharge mass spectrometry
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What technique is sometimes used for organomatallics and pesticides?
GC-ICP-MS
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What are 3 ways to deal with isobaric interferences in ICP-MS?
- 1. Use a mathematical correction
- Use a collision cell to either:
- 2. Change interfering ions
- 3. Change analyte
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Two modes for reaction cells in ICP-MS-MS
- Kinetic (collision)
- Reaction
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KED
Kinetic Energy Discrimination
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GD-MS is good for...
- Fairly specific applications
- ppt detection of conductive samples
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Does ICP-MS create anions or cations?
cations (therefore you don't detect Cl-, I-, F-, etc.)
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Samples run on ICP-MS should have ___ 0.2% TDS. What can you do if you're analyzing a high TDS sample?
- Less than
- Dilute your sample
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Can ICP-MS give isotopic information?
Yes, it's resolution is that high!
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The resolution of a high-res ICP-MS can be changed by...
Adjusting the width of the entrance and exit slits into the spectrometer
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What are some limitations of high resolution ICP-MS systems?
- High cost
- Slower speed (for magnetic sector)
- Increase in resolution comes with decrease signal intensity, limiting detection limits
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CEM
Channel Electron Multiplier
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Do ICP-MS detectors last forever?
No, the active coating gets consumed, so they must be replaced every 6-18 months
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Name two things that can damage an ICP-MS detector
- High signal count rates
- Light
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