Analytical instrumentation — suitable use of mass spectrometry For which sample type is mass spectrometry classically employed to perform detailed compositional (especially isotopic) analysis in process and laboratory settings?

Introduction / Context:
Mass spectrometry separates ionized species according to mass-to-charge ratio. A key strength is the ability to resolve and quantify isotopes of the same element, which differ only by neutron number but not by chemical behavior.

Given Data / Assumptions:

• Question asks for the sample type most directly associated with compositional analysis by a mass spectrometer.
• Mass spectrometers measure isotopic abundance with high precision.

Concept / Approach:
Because isotopes have distinct masses, mass spectrometry is uniquely well-suited to their identification and quantification. While gases, solids, and alloys can also be analyzed after suitable sample preparation and ionization, the canonical, textbook application is isotopic analysis (e.g., deuterium vs protium, C-13 vs C-12).

Step-by-Step Solution:
Identify the technique’s primary advantage: mass resolution → isotopic separation.Select the choice that explicitly matches this advantage.Therefore, the best answer is “An isotope.”

Verification / Alternative check:
Radiogenic dating, tracer studies, and isotope ratio mass spectrometry (IRMS) are standard applications confirming this selection.

Why Other Options Are Wrong:

• Natural gas / solids / alloys: analyzable but not uniquely tied to the core capability highlighted by the question; they require specific inlet and prep methods.

Common Pitfalls:

• Assuming “mass spec = any composition.” True in broad terms, but its hallmark is isotopic resolution.

Final Answer:
An isotope