The Arab Experts’ Office

AUPAM learning reference

Mass spectrometry: from A to Z

A practical learning reference: follow the ion, understand the spectrum, develop the method and defend the result.

18learning units54focused lessons3worked cases
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First module open for preview

Explore the complete first module below, including three lessons and an applied question. The other 17 modules, worked cases and advanced tools require authorised access.

  1. Sample and separation
  2. Ion production
  3. Mass analysis
  4. Electrical detection
  5. Data and interpretation

The analyser and interface use controlled pressure regions; collision cells deliberately create selected ion–gas interactions.

Learning path 1

Foundations

1What a mass spectrometer measuresSeparate the analytical question from the signal the instrument actually records.

From sample to ion

A mass spectrometer works with gas-phase ions. An ion source creates charged species; electric or magnetic fields guide or distinguish them; the measurement is expressed against mass-to-charge ratio, m/z. The instrument does not directly weigh a neutral molecule. You must identify the ion, its charge and any adduct before inferring the neutral mass.

Qualitative and quantitative questions

Identification asks which chemical explanation fits the evidence. Quantitation asks how much analyte is present using a validated relationship between response and concentration. A strong peak alone answers neither question: response also depends on ionization, transmission, the matrix and acquisition settings.

Define the task before choosing the instrument

Write the analyte, matrix, expected range, required identification confidence and decision to be supported. A trace assay in plasma and an unknown-impurity investigation can require different preparation, acquisition and acceptance rules even when both use LC-MS.

Apply the idea

A compound gives twice the peak area after changing the mobile phase. Has its concentration doubled?

Reveal the reasoning

No. The source response or separation may have changed. Compare matched standards, an appropriate internal standard and quality controls under the same method before calculating concentration.

Your task: Write a five-line analytical purpose statement for one laboratory sample.

Further reading: Waters

2

The ion path, vacuum and detection

Locate where a problem can arise between the sample and the recorded spectrum.

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3

Choosing ESI, APCI or APPI

Match the source to the chemistry and the matrix.

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Learning path 2

Instrumentation

4

GC-MS, MALDI, elemental and surface MS

Recognise when a problem belongs to a different MS platform.

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5

Mass analysers: what their designs allow

Compare instrument capabilities against the analytical task.

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6

MS/MS, scan modes and acquisition timing

Choose what to record and keep enough information across each peak.

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Learning path 3

Understanding the sample

7

Mass, charge, isotopes and adducts

Interpret a measured m/z without confusing it with neutral molecular mass.

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8

Reading chromatograms and mass spectra

Build an identification from several compatible observations.

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9

Sample preparation, recovery and matrix effects

Distinguish analyte loss from a change in ion response.

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Learning path 4

Building the method

10

LC coupling, columns and mobile phases

Make separation and ionization work together.

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11

Method development, tuning and calibration

Develop a method around its intended performance.

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12

Quantitation and internal standards

Calculate a defensible concentration rather than read a peak as an amount.

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Learning path 5

Proving performance

13

Validation: demonstrate fitness for purpose

Select validation evidence that fits the application.

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14

Sequence design and batch review

Make the batch capable of revealing its own problems.

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15

Routine operation and preventive maintenance

Use condition-based checks and safe instrument procedures.

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Learning path 6

From diagnosis to reporting

16

Logical troubleshooting

Move from a symptom to a discriminating experiment.

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17

Advanced applications and their limits

Understand what additional dimensions contribute to an answer.

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18

Data integrity and the final report

Make every reported conclusion traceable to its evidence.

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