Correct Answer: 4. Mass spectrophotometer

Mass-to-charge (m/z) ratio measures ionized molecular fragments separated by their mass and charge in a mass spectrometer (often called mass spectrophotometer). This technique ionizes samples and uses electric/magnetic fields to resolve m/z values.

Option Analysis

1. Gas chromatography
GC separates volatile compounds by partitioning between gas mobile phase and stationary phase based on boiling point/polarity. Detects via FID/MS but doesn’t measure m/z directly—requires MS coupling.​

2. UV-Vis spectrophotometer
Measures light absorbance (190-800nm) to quantify concentration via Beer-Lambert law. Analyzes electronic transitions, not ionic mass/charge ratios.​

3. Fluorescence spectrophotometer
Detects emitted light after excitation, used for fluorescent molecules. Emission spectra reveal molecular environment, not m/z values.​

4. Mass spectrophotometer
Ionizes sample → accelerates ions → separates by m/z via quadrupoles, time-of-flight, or magnetic sectors → detects. Core principle of mass spectrometry.

Mass-to-charge ratio m/z measured by mass spectrophotometer enables precise molecular identification in analytical chemistry and biotech research. This mass-to-charge ratio m/z measured mass spectrophotometer article clarifies techniques for GATE Chemistry, CSIR NET, and lab professionals.

How Mass Specs Work

Sample vaporizes → electron impact ionization creates [M]+ ions → quadrupole/TOF analyzer separates by m/z = (m/q) → detector plots spectrum. Peak at 44 = CO2+ fragment.​​

Technique Comparison Table

m/z peaks yield exact mass, isotope patterns, fragmentation for structure elucidation.​

Exam Applications

Used in proteomics (peptide mass fingerprinting), forensics (drug ID), pharma (impurity profiling). Mnemonic: “Mass spec = m/z detective; others = no ions.”