User Guide

For an introduction to the application and use of Certified Reference Materials in absorption spectrophotometry

Starna Scientific offers the world's widest range of reference materials for qualifying the photometric accuracy and linearity of UV spectrophotometers, covering all wavelengths from the far UV to the visible and NIR. Some, such as the new Deep UV references, are unique to Starna.


Potassium Dichromate solutions 
(235 - 430 nm)

The most widely recognised reference material for checking the photometric accuracy and linearity  of a UV spectrophotometer. It is accepted for this purpose by most Pharmacopoeias and Standardisation Bodies, including:

European Pharmacopoeia
Deutsches Arzneibuch (German Pharmacopoeia).
United States Pharmacopoeia
American Society for Testing and Materials (ASTM)
Therapeutic Goods Administration (Australia)
British Pharmacopoeia

A range of 12 solutions covers absorbance values  from 0.2 A  to 3.6 A at wavelengths from 235 nm to 350 nm. An additional reference is available calibrated at 430 nm (absorbance 0.95 A). These references are available singly or in any combination and as convenient sets, each of five references and a blank solution, covering low (up to 1.5 A) and high (up to 3.0 A) absorbance ranges. They are also used in Starna’s UV Instrument Qualification Kits, which contain all you need to comply with Pharmacopoeia requirements.

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Instrument Qualification Kits


Nicotinic Acid (210 - 260 nm)

Nicotinic acid in dilute hydrochloric acid has peaks at 213 nm and 261 nm that can be used to qualify photometric accuracy and linearity in the far UV. Four different concentrations cover an absorbance range from approximately 0.25 A to 1 A, and are  available singly or in any combination.

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Deep UV Reference (190 - 230 nm)   

This novel reference material is suitable  for qualifying UV spectrophotometers in the range 190-230 nm.
The reference is certified for absorbance qualification at approximately 191 nm, 209 nm and 226 nm.  Nominal absorbance values are 1.2 A, 0.6 A and 1.0 A respectively.

This reference is also certified  for wavelength qualification.

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Starna Green Broadband References (250 - 650 nm) 

 

Starna Green has broad peaks at  258 nm, 416 nm and 630 nm - an alternative to Potassium Dichromate and also a great option for instruments with wider Spectral Band Widths (up to 20 nm). Four different concentrations cover an absorbance range from approximately 0.25 A to 1.A and the references are available singly or in any combination. This reference material may also be used to qualify the wavelength scale.

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Metal-on-Quartz Neutral Density Filters (250 - 635 nm) 

These filters are equivalent to  NIST SRM 2031. Absorbance values are certified at 250, 280, 340, 360, 400, 465, 500, 546.1, 590 and 635 nm. Approximate values available are:
90% T  (0.04 A), 50% T (0.3 A), 30% T (0.5 A), 10% T (1.0 A), 3%T (1.5 A) and 1% T (2.0A). This type of filter can also be supplied with certified values in the NIR, up to 2500 nm.
Before purchase, users should check that these filters are compatible with their spectrophotometer - see data sheet. 

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Neutral Density Filters (440 - 635 nm)

These references can be used to qualify the absorbance accuracy and linearity of visible spectrophotometers with a spectral bandwidth of 6.5 nm or less, over the wavelength range 440 nm – 635 nm. 

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Combined Holmium/Neutral Density Glass

With this combined filter, the holmium spectrum is superimposed on an approximately constant 1 A background, useful as an absorbance accuracy check. 7 peak wavelengths are certified at nominal values of 361, 419, 446, 454, 460, 537 and 638 nm.

Absorbance values, nominally 1 A, are certified at wavelengths between the holmium peaks at 431, 516, 557, 594 and 623 nm.

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Combined Didymium/Neutral Density Glass

With this combined filter, the holmium spectrum is superimposed on an approximately constant 1 A background, useful as an absorbance accuracy check. 9 peak wavelengths are certified at nominal values of 473, 514, 530, 572, 586, 739, 748, 807 and 879 nm.

Absorbance values, nominally 1 A, are certified at wavelengths between the didymium peaks, at 410, 455, 550, 637 and 773 nm.

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