Introduction to Troubleshooting in LCMS Quiz

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* 1. What is the most widely used ionisation technique used in LCMS?

APCI

APPI

ESI

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* 2. Which of the following practices is most important to prevent clogging in the LCMS system?

Use non-volatile buffers at high concentrations to improve chromatographic results

Filter both samples and standards and use volatile additives to avoid particulate buildup

Leave purely aqueous eluents in the bottles for long periods of time to settle particulates

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* 3. How many data points do you need to describe a peak sufficiently?

2-4

100

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* 4. Which of the following is the most likely course of sudden, irregular sawtooth pressure profiles in the LCMS system?

Worn pump seals or faulty check valves

Leaks in the LCMS interface

Contamination or blockage of the column

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* 5. What is the most likely reason an expected chromatographic peak is not detected in the LCMS run?

The sample concentration is well above the instrument upper limit and saturates the detector

The analyte elutes outside the scheduled MRM acquisition window or retention time has shifted

The data acquisition rate has increased

The column has begun to deteriorate and void

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* 6. In the event of ghost peaks suddenly appear in your sample, you should:

Check the needle rinse lines have the correct rinse solvent and they haven't run dry

Make fresh solvents with clean glassware to eliminate contamination from old mobile phases

Ensure LCMS grade solvents are used on the instrument

Purge the metering pump

All of the above

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* 7. What is the purpose of tuning the Mass Spectrometer?

To holistically look at the entire LCMS system

To guarantee the system is free of contaminants

To act as a diagnostic tool to indicate the cleaning or service required of the mass spectrometer for known probes

To find the conditions required for a method

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* 8. Which of the following is the most likely action to take first when you observe an elevated MS baseline with persistent background peaks and reduced S/N?

Increase the injection volume to boost analyte signal and overcome the elevated baseline.

Run blank injections and test the solvents alone to determine whether the mobile phase or solvent bottles are the contamination source.

Immediately replace the analytical column without further diagnostics.

Change the autosampler vial type to a different glassware brand to eliminate matrix effects.

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* 9. What is the most likely reason for progressive shortening retention times across consecutive reversed phase LC runs?

The column has not reached equilibrium yet

The injection volume is too much for the column capacity

The flow rate is decreasing

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* 10. What is the role of the calibration standards in a QTOF?

To set the analytical conditions for the separation

To act as internal standards for quantification

Ensure mass accuracy and maintain stability

To clean the ion source

Introduction to Troubleshooting in LCMS Quiz

Question Title

* 1. What is the most widely used ionisation technique used in LCMS?

Question Title

* 2. Which of the following practices is most important to prevent clogging in the LCMS system?

Question Title

* 3. How many data points do you need to describe a peak sufficiently?

Question Title

* 4. Which of the following is the most likely course of sudden, irregular sawtooth pressure profiles in the LCMS system?

Question Title

* 5. What is the most likely reason an expected chromatographic peak is not detected in the LCMS run?

Question Title

* 6. In the event of ghost peaks suddenly appear in your sample, you should:

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* 7. What is the purpose of tuning the Mass Spectrometer?

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* 8. Which of the following is the most likely action to take first when you observe an elevated MS baseline with persistent background peaks and reduced S/N?

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* 9. What is the most likely reason for progressive shortening retention times across consecutive reversed phase LC runs?

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* 10. What is the role of the calibration standards in a QTOF?

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* 11. Full Name

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* 12. Email Address

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* 13. Company / Institution