UV-Visible spectroscopy is one of the most widely used instrumental techniques in analytical chemistry, especially in the life sciences. As such, it is one of the most regulated, by pharmacopoeias and quality assurance bodies world-wide. Starna supplies the world’s widest range of Certified Reference Materials (CRMs) for the qualification of UV-Visible Spectrophotometers to help instrument users achieve compliance – with confidence. Ideally, references should be chosen whose calibrated values “bracket” the conditions to be used for analysis. While regulators like the Pharmacopoeias may recommend certain references, any Certified Reference Material with appropriate certified values may be used for qualification

Instrument Qualification Kits - Tools for Easier Compliance

These kits allow instrument qualification over the stated wavelength and absorbance ranges for compliance with EP 2.2.25 and USP . References are provided to qualify wavelength accuracy, absorbance accuracy and 3-point linearity, stray light and resolution/bandwidth.


Absorbance References


Potassium Dichromate (235-430 nm) - the most widely used reference for absorbance accuracy and linearity  

Nicotinic Acid (210-260 nm) – recommended by Pharmacopoeias for absorbance accuracy and linearity in the far UV

Starna Green (250-650 nm) - Unique general-purpose reference for absorbance accuracy and linearity and wavelength accuracy in the UV and visible

Deep UV Reference (190-220 nm) – qualification in the deep UV: unique to Starna

Metal-on-Quartz Neutral Density Filters (250-635 nm) - durable filters with UV capability – now recommended by USP

Neutral Density Filters (440-635nm) - glass filters with absorbances from 0.04 A to 3.5 A

Combined Holmium/Neutral Density glass (360 - 640 nm)– 1 A absorbance check with wavelength calibration

Combined Didymium/Neutral Density glass (430 - 890 nm)– 1 A absorbance check with wavelength calibration


Wavelength References


Holmium Oxide Liquid (240-650 nm) - the most widely used reference for wavelength accuracy – cited by all major Pharmacopoeias

Cerium Oxide liquid (200-300 nm)  - recommended by Pharmacopoeias for wavelength accuracy in the far UV.

Didymium Oxide Liquid (290-870 nm) – cited by the Pharmacopoeias and with useful peaks in the NIR

Combined Holmium/Didymium Oxide Liquid (240 to 795 nm) – evenly spaced peaks over a wide range 

Starna Green (250-650 nm) - Unique general-purpose reference for absorbance accuracy and linearity and wavelength accuracy in the UV and visible

Holmium Oxide Glass (270-640 nm) – more robust and useful for routine checks  

Didymium Glass (430 - 890 nm) – more robust and useful for routine checks

Starna wide-range wavelength reference (335 - 1945 nm) -20 peaks from UV to NIR.

Combined Holmium/Neutral Density glass (360 - 640 nm) – wavelength calibration with 1 A absorbance check

Combined Didymium/Neutral Density glass – (430 - 890 nm) - wavelength calibration with 1 A absorbance check

Deep UV Reference (190-220 nm) – qualification in the deep UV: unique to Starna

SamariumOxide Liquid (230 – 560 nm) – for the commonly used region from 200 nm to 500 nm 


Stray Light (Stray Radiant Energy) References


Stray Light Cut-off Filters –Specified Wavelength Method – (175-385 nm) accepted by European and US  Pharmacopoeias

Stray Light Cut-off Filters – Filter Ratio Method (175-385 nm)  – recommended by US Pharmacopeia for measuring low stay light levels

Stray Light Glasses (220-440 nm) - convenient routine check for stray light


Resolution (Spectral Bandwidth) References


Toluene in Hexane  (265 – 270 nm) - the most widely used resolution reference – accepted by all major Pharmacopoeias

Toluene in Methanol (265 – 270 nm) - resolution check for Derivative Spectroscopy.

Benzene vapour (230-270 nm)  - resolution reference for instruments with spectral bandwidths less than 1 nm 

 

 

Instruments for use in the visible region only are less subject to regulation than those used in the UV. Good practice, however, requires that they are also qualified to ensure that they are performing correctly. Starna supplies a range of Certified Reference Materials for use in the visible region.

Ideally, references should be chosen whose calibrated values “bracket” the conditions to be used for analysis.


Visible Instrument Qualification Kit

Product Enquiry

Part number: RM-1N3N5DHG 

A set of robust glass reference materials for qualifying visible-only spectrophotometers for photometric accuracy and wavelength calibration.

Neutral Density Filters (1.00, 0.50 & 0.25 A) - Absorbance Accuracy, 440-635 nm.  More information

Holmium Glass Filter - Wavelength Accuracy, 240 - 640 nm. More information


Absorbance References


Neutral Density Filters (440-635nm) - glass filters with absorbances from 0.04 A to 3.5 A

Metal-on-Quartz Neutral Density Filters (250-635 nm)– equivalent to NIST SRM 2031

Starna Green (250-650 nm) - wavelength and absorbance for instruments with bandwidths >5nm

Combined Holmium/Neutral Density glass (360 - 640 nm) – check absorbance and wavelength with one filter! 

Combined Didymium/Neutral Density glass (430 - 890 nm) – check absorbance and wavelength with one filter!


Wavelength References


Holmium Oxide Liquid (240-650 nm) - the most widely used reference for wavelength accuracy 

Didymium Oxide Liquid (290-870 nm) – useful peaks in the NIR

Starna Green (250-650 nm) - wavelength and absorbance for instruments with bandwidths >5nm

Holmium Oxide Glass (270-640 nm) –  useful for routine checks  

Didymium Glass (430 - 890 nm) –  useful for routine checks

Starna wide-range wavelength reference (335 - 1945 nm) - 20 peaks for wavelength calibration from UV to NIR. 

Starna Holmium Oxide/Neutral Density glass (360 - 640 nm) – check absorbance and wavelength with one filter! 

Starna Didymium Oxide /Neutral Density glass (430 - 890 nm) – check absorbance and wavelength with one filter! 

Samarium Oxide Liquid (230 – 560 nm) – narrow peaks throughout the spectrum

 



The Near-infrared region is usually defined as the range of wavelengths from 750 nm to 2500nm. Starna has developed reference materials specifically designed for absorbance qualification in this region.


Metal-on-Quartz Neutral Density Filters (250 - 3200 nm)

This Reference Material can be used to qualify the Absorbance scale, in the ultra-violet, visible and near-infrared regions of the spectrum (250 nm to 3200 nm) of spectrophotometers with spectral bandwidths not exceeding 6.5 nm.  Absorbance and Transmittance values are certified at 250.0, 360.0, 465.0, 546.1, 635, 1100, 1700, 2210, 2500, and  2850 nm. Before purchase, users should check that these filters are 
compatible with their spectrophotometer - see data sheet.

More information


NIR Neutral Density Filters (800 nm to 3200 nm) 

This Reference Material is specially designed for the wavelength qualification of near-infrared reflectance spectrophotometers over the range 900 nm to 2600 nm. These references can be used to qualify the absorbance accuracy and linearity of near-infrared spectrophotometers with a spectral bandwidth of 6.5 nm or less, over the wavelength range 800 nm - 3200 nm. Calibration values (in % Transmission and Absorbance) are certified at 1100, 1700, 2210, 2500 and 2850 nm.

More information