Starna Green is an excellent general-purpose reference for the routine qualification of ultraviolet and visible spectrophotometers in the wavelength range 250 nm – 650 nm. It was specially developed for use with instruments having wider bandwidths (up to 20 nm) but is a useful reference for all instruments. Three peaks are available for wavelength qualification (258, 416 and 630 nm) and the reference can be used at absorbances up to 5 A. Starna Green is very stable, non-toxic and REACH compliant.
This reference is also available specially packaged for the qualification of dedicated microvolume and drop technology instrumentation.
Most reference materials available for instrument wavelength qualification are chosen for their well-defined spectra, with sharp absorption bands, and are usually recommended for instruments with spectral bandwidths of 3 nm or less. This is partly because most absorption bands are asymmetric, so the apparent peak wavelength will change with bandwidth and partly because wider bandwidth instruments may be unable to resolve some peaks at all.
The use of aqueous dye solutions, however, is an established and well-recognised method for the validation of the absorbance scale and linearity of a spectrophotometer. Starna Green is a specially formulated dye solution with three broad but well-defined peaks that can be certified for both wavelength and absorbance value in the UV and visible regions, at bandwidths up to 20nm.
