Analytical Instrumentation Practice Test 8

1. Which of the following statements about mass spectrometers are not true?

Time of flight mass spectrometers have poor resolution

Time of flight mass spectrometer has the ability to record the entire mass spectrum at a time

Conventional spectrometer detects only one peak at a time

All spectrometers have the ability to record the entire mass spectrum at a time

2. Under which of the following temperatures is the ionisation chamber maintained?

200^oC

300^oC

100^oC

400^oC

3. Which of the following techniques do not enhance sensitivity by a factor of 10 at normal operating conditions?

Time averaging

Optimization of instrumental parameters

Optimization of sample volume

Optimization of noise

4. In a mass spectrometer, the ion currents are measured using which of the following?

Electrometer tube

Scintillation counter

Ion counter

Electric fields

5. Which of the following does not affect the resolution of the instrument?

Changing length of drift tube

Changing length of electrode

Changing slope of scan line

Quality of machining of the rods

6. Suppression of frequencies which contain no signal does which of the following?

Decreases S/N ratio

S/N ratio is kept constant

S/N ratio becomes 1

Increases S/N ratio

7. If to one pair of electrodes one potential with one sign is applied, which of the following is applied to the other pair of electrodes?

Different potential with same sign

Same potential with same sign

Different potential with different sign

Same potential with different sign

8. Which of the following is the heart of quadrupole instrument?

DC potential

Detector

Choke

Electrodes

9. Which of the following are true about dynodes used in discrete dynode electron multiplier?

All dynodes are held at very low potential

Successive dynodes are held at lower potential

The dynodes are all kept at same voltage

Successive dynodes are held at higher potential

10. Which of the following statements is not true about mass spectrometry?

It is suitable for library retrieval

It has great sensitivity

It is suitable for data storage

Impurities of masses different from the one being analysed interferes with the result