Analytical instrumentation – what does a mass spectrometer analyze best? Mass spectrometry is especially suited for composition analysis and identification of which of the following?

Introduction / Context:
Mass spectrometry (MS) separates ions by mass-to-charge ratio and detects their abundances. Because different isotopes of an element have different masses, MS is exceptionally powerful for isotope identification and ratio measurements, widely used in geochemistry, nuclear science, environmental tracing, and quality control of gases and organics.

Given Data / Assumptions:

• MS requires analytes to be converted to gas-phase ions.
• Ion optics and mass analyzers (quadrupole, TOF, magnetic sector) separate m/z.
• Detector current is proportional to ion abundance.

Concept / Approach:
Isotopic variants differ only in neutron number, thus mass. When ionized, their m/z values shift accordingly, producing resolvable peaks that unveil isotopic composition with high sensitivity and precision. While alloys can be studied by MS after appropriate sampling (e.g., spark source, laser ablation), the technique excels most naturally at isotope analysis due to the direct mass distinction. Bulk solids without vaporization/ionization cannot be analyzed directly; sample introduction must create ions first.

Step-by-Step Solution:

Verification / Alternative check:
Applications like isotope ratio MS (IRMS) and accelerator MS are standard for isotopic fingerprints (e.g., C-13/C-12, O-18/O-16).

Why Other Options Are Wrong:

• Alloys: Possible with specialized sampling, but not the quintessential use highlighted in fundamentals.
• Solids (bulk, without vaporization): Incompatible with MS without ion generation.
• None of these: Incorrect because isotopes are a prime use-case.

Common Pitfalls:
Assuming MS directly “weighs” solids; all MS measurements are on ions in vacuum.

Final Answer:
Isotopes