Polymer Case Study Quiz (MALDI)

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I have NOT done the Polymer Analysis case study by MALDI-TOF MS before.
I have done the Polymer Analysis case study by MALDI-TOF MS before.

1. Why is internal calibration possible for PMMA 3800?

The factory default calibration was known to be within half a Dalton
theoretical masses can be assigned to many polymer peaks
the terminal group information was known
all of the above

2. Why can't you use one calibration for all polymers in this study?

calibration is mass dependent
calibration depends on laser intensity
the optimal instrument settings may be different
all of the above

3. Which of the following is false?

reflectron mode is more sensitive for low mass polymers (<5000 amu)
reflectron mode is less sensitive compared to linear mode
only reflectron mode should be used to calibrate the instrument
reflectron mode gives higher resolution than linear mode

4. What information could be derived from a good mass spectrum of MW average 3800?

monomer mass
charge state
degree of polymerization
all of the above

5. Which one is the correct terminal group for PMMA 3800 in this case study?

-H and -H
-H and Na+
-CH3 and -H
-CH3 and -OH

6. Which of the following settings should not be used for a polymer with MW average >10,000?

higher delay time than low mass polymer
linear mode
higher low mass gate value than for a low mass polymer
highest laser intensity

7. Which factor has the least effect on sensitivity (ion signal/amount)?

input band
laser intensity
laser shots
delay time

8. Delay time effects

mass accuracy
all of the above

9. Increasing the laser shots averaged from 16 to 256 should improve the S/N by?

4X, but with reduced resolution
16X, but with reduce resolution

10. What is the correct relationship between Mn, Mw and Mz for PDI ≠ 1?


11. Which charge state is most common in maldi-tof MS?


12 . Which of the following is the most reasonable mass-range that should be used to acquire a polymer mass spectrum with Mw = 3800 and PDI =1.2?

1000 to 6000
500 to 4000
3000 to 4600
3600 to 4000

13. What is the typical resolution (R=m/Dm at FWHM) you can achieve on the MALDI TOF-MS used in linear mode?

about R= 30,000
better than R=15,000
R= 200 to 3000

14. Which scan mode gives the best mass accuracy?

Delayed extraction
linear with delayed extraction
reflector with delayed extraction
combined linear and reflectron mode with delayed extraction

15. When using a laser intensity that is higher than optimal, which of the following is false?

Ion counts are greater
Low resolution
signal could become saturated
mass range is extended