Toluene in Hexane (265 – 270 nm)
A solution of toluene in hexane is the most widely used reference for qualifying the Spectral Bandwidth (SBW) of a UV spectrophotometer. It is accepted for this purpose by most Pharmacopoeias and Standardisation Bodies.
It can be used with spectrophotometers having spectral bandwidths of 3 nm or less.
Toluene In Methanol (265 – 270 nm)
This reference was described in earlier editions of European Pharmacopoeia (EP) Chapter 2.2.25 for use as a resolution check in Derivative Spectroscopy.
Benzene Vapour (230-270 nm)
This reference is useful as a resolution check for instruments with spectral bandwidths less than 1 nm. Benzene vapour has characteristic peaks that may or may not be displayed, depending on the SBW of the instrument.
Note: Benzene vapour is not suitable for use with photodiode array spectrophotometers.