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Diode-array detection

Seen on chromatogram headers, certificates.

Definition

An ultraviolet detector that records absorbance across a whole wavelength range at every point in a run rather than at one fixed wavelength. Full-spectrum HPLC with diode-array detection is the purity method run on every accepted sample, and it is why each peak carries a spectrum as well as an area.

A diode array measures light absorbed, not mass and not amount. A peak whose spectrum matches the expected compound is consistent with it; how many milligrams are in the vial is a separate measurement.

Related terms

Detection wavelength
The wavelength at which absorbance is recorded.
Area purity
The area of the principal peak expressed as a percentage of the total integrated detected response in the run, under stated method conditions and at a stated detection wavelength.
Reference spectrum
A spectrum recorded from material of known identity, which a sample spectrum is compared against.

About identity confirmation

The spectroscopic techniques an identity conclusion is built from, and what each of them can settle.

FTIR-ATRRaman spectroscopyCapillary electrophoresisUV-Vis spectroscopyConfirmatory testing

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