Analytical Chemistry & Spectroscopy — 60 Terms Defined

High-Resolution Mass Spectrometry Analytical Chemistry & Spectroscopy Da Mass spectrometry capable of measuring mass to four or more decimal places, allowing molecular formulae to be determined.

Inductively Coupled Plasma Mass Spectrometry Analytical Chemistry & Spectroscopy ppb A technique combining a plasma ion source with a mass spectrometer for ultra-trace multi-element analysis.

Infrared Spectroscopy Analytical Chemistry & Spectroscopy cm⁻¹ A technique that identifies functional groups from the infrared frequencies a molecule absorbs as its bonds vibrate. ν̃ = (1/2πc)√(k/μ)

Integration in NMR Analytical Chemistry & Spectroscopy Dimensionless The measurement of the area under each NMR signal, which is proportional to the number of nuclei giving rise to it. area ∝ number of nuclei

Iodometry Analytical Chemistry & Spectroscopy mol/L A redox titration in which iodine liberated by the analyte is titrated with standard thiosulfate. I₂ + 2S₂O₃²⁻ → 2I⁻ + S₄O₆²⁻

Isotopic Peak Analytical Chemistry & Spectroscopy Da A peak appearing at a higher mass than the main ion because the molecule contains a heavier isotope. M+1, M+2

Limit of Detection Analytical Chemistry & Spectroscopy Various The smallest concentration of analyte that can be reliably distinguished from the blank. LOD = 3σ_blank / m

Limit of Quantitation Analytical Chemistry & Spectroscopy Various The lowest concentration at which the analyte can be measured with acceptable precision and accuracy. LOQ = 10σ_blank / m

Mass Spectrometry Analytical Chemistry & Spectroscopy Da A technique that separates ionised molecules and fragments according to their mass-to-charge ratio. m/z

Matrix Analytical Chemistry & Spectroscopy Dimensionless Everything in a sample other than the analyte itself.

Mobile Phase Analytical Chemistry & Spectroscopy mL/min The fluid that carries the sample through the stationary phase during chromatography.

Molar Absorptivity Analytical Chemistry & Spectroscopy L/(mol·cm) The absorbance of a one molar solution measured over a one centimetre path length. ε = A / (c l)

Molecular Ion Peak Analytical Chemistry & Spectroscopy Da The peak in a mass spectrum corresponding to the intact molecule after loss of a single electron. M⁺·

Nuclear Magnetic Resonance Spectroscopy Analytical Chemistry & Spectroscopy MHz A technique that probes molecular structure using the resonance of atomic nuclei in a strong magnetic field. ν = γB₀ / 2π

Outlier Test Analytical Chemistry & Spectroscopy Dimensionless A statistical procedure for deciding whether a suspect result differs enough from the others to be rejected. Q = |suspect − nearest| / range

Precipitation Titration Analytical Chemistry & Spectroscopy mol/L A titration in which the analyte and titrant combine to form an insoluble product. Ag⁺ + Cl⁻ → AgCl(s)

Primary Standard Analytical Chemistry & Spectroscopy g/mol A highly pure, stable substance that can be weighed accurately and used directly to prepare a solution of known concentration.

Qualitative Analysis Analytical Chemistry & Spectroscopy Dimensionless Analysis carried out to establish which species are present in a sample.

Quantitative Analysis Analytical Chemistry & Spectroscopy Various Analysis carried out to determine the amount or concentration of a species in a sample.

Raman Spectroscopy Analytical Chemistry & Spectroscopy cm⁻¹ A vibrational technique based on the small shift in frequency of light scattered inelastically by molecules. Δν̃ = ν̃_incident − ν̃_scattered

Random Error Analytical Chemistry & Spectroscopy Various An error that varies unpredictably in size and direction between repeated measurements.

Redox Titration Analytical Chemistry & Spectroscopy mol/L A titration in which the reaction between titrant and analyte involves electron transfer.

Retention Factor Analytical Chemistry & Spectroscopy Dimensionless The ratio of the distance travelled by a component to the distance travelled by the solvent front. Rf = d_spot / d_solvent

Sampling Analytical Chemistry & Spectroscopy g The process of selecting a small portion of material that genuinely represents the bulk being analysed.