These reference materials have been specially developed for the qualification of the dedicated low volume (< 5 ul) and short path length (< 1 mm) instrumentation offered by several vendors for use when sample is often at a premium. They are also ideal for qualifying conventional instruments when they are used with ultra-low-volume cells such as the Starna DMV cell. As the use of these references involves their physical transfer by the user in to the measuring device, this material is fully REACH compliant.  

Description and Discussion

Many microvolume spectrophotometers have relatively wide spectral bandwidths, up to 8 nm in some cases. 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. References with sharp absorption bands may therefore be unsuitable for the qualification of these instruments.

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, highly stable 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.

Typical spectra


The reference is formulated to give an approximate absorbance of 1A at each of the certified wavelengths, 258, 416 and 630 nm, at a nominal path length of 1 mm.

The references are supplied in vials with screw-cap closure for ease of handling, and from which it is easy to transfer them to the instrument under test using a micropipette or syringe. Each vial contains 1.5 ml of Starna Green solution.


Catalogue Number

  Catalogue Number
Starna Green Microvolume reference, 1 x 1.5 ml vial RM-SG10-SC1  
Starna Green Microvolume reference, 2 x 1.5 ml vials RM-SG10-SC2  
Starna Green Microvolume reference, 4 x 1.5 ml vials RM-SG10-SC4