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Analytical Chemistry & Spectroscopy

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Analytical Chemistry & Spectroscopy

High-Resolution Mass Spectrometry

Mass spectrometry capable of measuring mass to four or more decimal places, allowing molecular formulae to be determined.

Da
Analytical Chemistry & Spectroscopy

Inductively Coupled Plasma Mass Spectrometry

A technique combining a plasma ion source with a mass spectrometer for ultra-trace multi-element analysis.

ppb
Analytical Chemistry & Spectroscopy

Infrared Spectroscopy

A technique that identifies functional groups from the infrared frequencies a molecule absorbs as its bonds vibrate.

ν̃ = (1/2πc)√(k/μ) cm⁻¹
Analytical Chemistry & Spectroscopy

Integration in NMR

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 Dimensionless
Analytical Chemistry & Spectroscopy

Iodometry

A redox titration in which iodine liberated by the analyte is titrated with standard thiosulfate.

I₂ + 2S₂O₃²⁻ → 2I⁻ + S₄O₆²⁻ mol/L
Analytical Chemistry & Spectroscopy

Isotopic Peak

A peak appearing at a higher mass than the main ion because the molecule contains a heavier isotope.

M+1, M+2 Da
Analytical Chemistry & Spectroscopy

Limit of Detection

The smallest concentration of analyte that can be reliably distinguished from the blank.

LOD = 3σ_blank / m Various
Analytical Chemistry & Spectroscopy

Limit of Quantitation

The lowest concentration at which the analyte can be measured with acceptable precision and accuracy.

LOQ = 10σ_blank / m Various
Analytical Chemistry & Spectroscopy

Mass Spectrometry

A technique that separates ionised molecules and fragments according to their mass-to-charge ratio.

m/z Da
Analytical Chemistry & Spectroscopy

Matrix

Everything in a sample other than the analyte itself.

Dimensionless
Analytical Chemistry & Spectroscopy

Mobile Phase

The fluid that carries the sample through the stationary phase during chromatography.

mL/min
Analytical Chemistry & Spectroscopy

Molar Absorptivity

The absorbance of a one molar solution measured over a one centimetre path length.

ε = A / (c l) L/(mol·cm)
Analytical Chemistry & Spectroscopy

Molecular Ion Peak

The peak in a mass spectrum corresponding to the intact molecule after loss of a single electron.

M⁺· Da
Analytical Chemistry & Spectroscopy

Nuclear Magnetic Resonance Spectroscopy

A technique that probes molecular structure using the resonance of atomic nuclei in a strong magnetic field.

ν = γB₀ / 2π MHz
Analytical Chemistry & Spectroscopy

Outlier Test

A statistical procedure for deciding whether a suspect result differs enough from the others to be rejected.

Q = |suspect − nearest| / range Dimensionless
Analytical Chemistry & Spectroscopy

Precipitation Titration

A titration in which the analyte and titrant combine to form an insoluble product.

Ag⁺ + Cl⁻ → AgCl(s) mol/L
Analytical Chemistry & Spectroscopy

Primary Standard

A highly pure, stable substance that can be weighed accurately and used directly to prepare a solution of known concentration.

g/mol
Analytical Chemistry & Spectroscopy

Qualitative Analysis

Analysis carried out to establish which species are present in a sample.

Dimensionless
Analytical Chemistry & Spectroscopy

Quantitative Analysis

Analysis carried out to determine the amount or concentration of a species in a sample.

Various
Analytical Chemistry & Spectroscopy

Raman Spectroscopy

A vibrational technique based on the small shift in frequency of light scattered inelastically by molecules.

Δν̃ = ν̃_incident − ν̃_scattered cm⁻¹
Analytical Chemistry & Spectroscopy

Random Error

An error that varies unpredictably in size and direction between repeated measurements.

Various
Analytical Chemistry & Spectroscopy

Redox Titration

A titration in which the reaction between titrant and analyte involves electron transfer.

mol/L
Analytical Chemistry & Spectroscopy

Retention Factor

The ratio of the distance travelled by a component to the distance travelled by the solvent front.

Rf = d_spot / d_solvent Dimensionless
Analytical Chemistry & Spectroscopy

Sampling

The process of selecting a small portion of material that genuinely represents the bulk being analysed.

g