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Dynamic Reaction Cell
Platinum Group Elements
Higher temperatures produce (more/less) emission lines
more (see slide 8 of INST395 Emission Spectrometry powerpoint)
Line spectra are produced by __ while band spectra are produced by ___
Name two setups for ICP detection. Which is faster?
- Simultaneous (faster)
CCD (or CID) What is it?
- Charge Couple Device
- Charge Injection Device
- A solid state simultaneous detector
What type of ICP detector requires mapping?
CCD/CID (solid state computer chip detector)
What are the two torch positions for ICP?
Which torch configuration has less interferences?
Which torch configuration can giver lower detection limits but is effected by dirty samples?
What are the zones in a plasma? Which are of interest to detect?
- Atomization (what you want to detect)
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
Ultrasonic nebulization can give ___ detection limits because ___ droplets make it to the plasma
- More (around twice as many)
Which nebulization technique is better for higher dissolved solids?
GF-ICP or ETV-ICP
- Graphite Furnace
- Electrothermal Vaporization
In order to use GF-ICP, the sample must be __
volatile (the entire thing must vaporize for accurate results)
Name two techniques that allow the direct analysis of solid samples by ICP without dissolving them
- Laser ablation (LA)
- Arc ablation (AA or ARC)
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
To get a more representative analysis using arc or laser ablation, what can you do?
Take readings at multiple spots
What torch configuration is used for ICP-MS?
Disadvantage of ICP-MS
- More finicky (room must be clean to get low LOD)
- Cones at MS interface get dirty easily and require cleaning
- Isobaric interferences
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
Sample ions enter the MS at __ speed
high (a supersonic jet)
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 What has it been replaced by?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)
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
Interference that occurs when another species has the same mass as the analyte
Two categories of ICP-MS interferences
- Spectral (isobaric interferences)
- Matrix (change physical properties of fluid or plasma)
Glow discharge mass spectrometry
What technique is sometimes used for organomatallics and pesticides?
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
Two modes for reaction cells in ICP-MS-MS
- Kinetic (collision)
Kinetic Energy Discrimination
GD-MS is good for...
- Fairly specific applications
- ppt detection of conductive samples
Does ICP-MS create anions or cations?
cations (therefore you don't detect Cl-, I-, F-, etc.)
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
Can ICP-MS give isotopic information?
Yes, it's resolution is that high!
The resolution of a high-res ICP-MS can be changed by...
Adjusting the width of the entrance and exit slits into the spectrometer
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
Channel Electron Multiplier
Do ICP-MS detectors last forever?
No, the active coating gets consumed, so they must be replaced every 6-18 months
Name two things that can damage an ICP-MS detector
- High signal count rates