- You are here:
-
Home
-
Certified Reference Materials
-
Visible Spectroscopy
-
Certified Reference Materials
- Visible Spectroscopy
In order to provide you with the best online experience this website uses cookies.
By using our website, you agree to our use of cookies. Learn more
Cookie Policy
What Are Cookies
As is common practice with almost all professional websites this site uses cookies, which are tiny files that are downloaded to your computer, to improve your experience. This page describes what information they gather, how we use it and why we sometimes need to store these cookies. We will also share how you can prevent these cookies from being stored however this may downgrade or 'break' certain elements of the sites functionality.
How We Use Cookies
We use cookies for a variety of reasons detailed below. Unfortunately in most cases there are no industry standard options for disabling cookies without completely disabling the functionality and features they add to this site. It is recommended that you leave on all cookies if you are not sure whether you need them or not in case they are used to provide a service that you use.
Disabling Cookies
You can prevent the setting of cookies by adjusting the settings on your browser (see your browser Help for how to do this). Be aware that disabling cookies will affect the functionality of this and many other websites that you visit. Disabling cookies will usually result in also disabling certain functionality and features of the this site. Therefore it is recommended that you do not disable cookies.
The Cookies We Set
When you submit data to through a form such as those found on contact pages or comment forms cookies may be set to remember your user details for future correspondence.
Third Party Cookies
In some special cases we also use cookies provided by trusted third parties. The following section details which third party cookies you might encounter through this site.
This site uses Google Analytics which is one of the most widespread and trusted analytics solution on the web for helping us to understand how you use the site and ways that we can improve your experience. These cookies may track things such as how long you spend on the site and the pages that you visit so we can continue to produce engaging content.
For more information on Google Analytics cookies, see the official Google Analytics page.
From time to time we test new features and make subtle changes to the way that the site is delivered. When we are still testing new features these cookies may be used to ensure that you receive a consistent experience whilst on the site whilst ensuring we understand which optimisations our users appreciate the most.
More Information
Hopefully that has clarified things for you and as was previously mentioned if there is something that you aren't sure whether you need or not it's usually safer to leave cookies enabled in case it does interact with one of the features you use on our site. However if you are still looking for more information then you can contact us through one of our preferred contact methods:
Contact our data compliance officer: data.protection@starna.com
Telephone: +44 (0)20 8500 1264
Starna Scientific Ltd.
52/54 Fowler Road
Hainault, Essex
IG6 3UT
United Kingdom
Last updated 6 June 2018
Visible References
Absorbance- Wavelength
- Holmium Oxide Liquid (240-650 nm)
- Didymium Oxide Liquid (290-870 nm)
- Holmium Oxide Glass (270-640 nm)
- Didymium Glass (430 nm to 890 nm)
- Combined Holmium/Neutral Density glass (360 - 640 nm)
- Combined Didymium/Neutral Density glass (430 - 890 nm)
- Starna Green (Broadband SBW instruments) (250-650 nm)
- Samarium Oxide Liquid (230-560 nm)
Combined Holmium/Didymium Oxide Liquid
Purpose
This Reference Material can be used to qualify the wavelength calibration, in the ultraviolet and visible regions of the spectrum (240 nm - 795 nm) of spectrophotometers with spectral bandwidths of 5 nm or less.
Description and Discussion
Holmium oxide and didymium (neodymium & praseodymium) oxide in 10% v/v perchloric acid, permanently sealed by heat fusion into a 10 mm far UV quartz cuvette.
Holmium and didymium (neodymium & praseodymium) oxides in perchloric acid have been separately used for the validation of the wavelength scale of UV and visible spectrophotometers for many years. Now, these materials are available from Starna as a combined reference, providing useful peaks that are interference-free over its whole wavelength range from 240 to 795 nm.
14 peaks are certified, with nominal values: 241, 287, 361, 416, 444, 482, 485, 522, 537, 575, 641, 732, 740 and 794nm.
Note: The above values are for guidance only. Because the absorption bands are asymmetric, measured values will bespectral bandwidth dependent. The Calibration Certificateaccompanying each Reference gives actual values measured at bandwidths of 0.10, 0.25, 0.50, 1.00, 1.50,2.00 and 3.00, 4.00 and 5.00 nm, and only these certified values should be used for instrument qualification. On request, Starna can provide certified values at otherwavelengths and bandwidth values.
Purpose
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 - 635 nm. They are accepted for this purpose by most pharmacopoeias and other regulatory bodies
Description and Discussion
Schott NG type glass filters, from which a wide range of transmission and absorbance can be produced, have been available for over forty years. All Starna neutral density filters are manufactured and certified in accordance with the ‘Technical Specification for Certification of Spectrophotometric NIST Traceable Reference Materials’ (NIST Special Publication 260-140). This recommends calibration at 440 nm, 465 nm 546.1 nm, 590 nm and 635 nm, and Starna filters are certified at these wavelengths. Starna absorbance references are calibrated at a bandwidth of 1 nm, however other bandwidths are available on request They can also be certified at other wavelengths to suit customer requirements with the provision that the 440 nm, 546.1 nm and 635 nm wavelengths are included for traceability.
A range of 18 filters is available from Starna, covering absorbance values from approximately 0.04 A to 3.5 A (see How to Order, below). Originally, these filters were manufactured with selected transmission values. Available transmission values and equivalent absorbances are:
|
% Transmission |
Absorbance |
|
92 |
0.04 |
|
79.4 |
0.10 |
| 73 | 0.14 |
| 60 | 0.22 |
| 56.5 | 0.25 |
| 50 | 0.30 |
| 40 | 0.40 |
| 30 | 0.52 |
| 25 | 0.60 |
| 20 | 0.70 |
| 10 | 1.00 |
| 6 | 1.22 |
| 3 | 1.52 |
| 1.5 | 1.82 |
| 1 | 2.00 |
| 0.3 | 2.52 |
| 0.1 | 3.00 |
| 0.06 | 3.22 |
| 0.03 | 3.52 |
This recommends calibration at 440 nm, 465 nm 546.1 nm 590 nm and 635 nm, and Starna filters are certified at these wavelengths.
NIST also lists three specifications for neutral density filter Standard Reference Materials (SRMs): SRM 930e, SRM 1930 and SRM 2930. These specifications also stipulate the maximum spectral bandwidth to be used at these wavelengths for certification measurements:
|
Wavelength(nm) |
440 |
465 |
546.1 |
590 |
635 |
|
SBW (NM) |
2.2 |
2.7 |
6.5 |
5.4 |
6.0 |
For those users wishing to work to these specifications, sets of filters equivalent to these SRMs are available (see How to Order). For convenience, but to comply with the SRM specifications, all certification measurements are made at a SBW of 1.0 nm. These sets consist of three filters together with an empty aluminium holder, to be used as a blank.
|
|
SRM 930e |
SRM 1930 |
SRM 2930 |
|||
|
|
%T |
A |
%T |
A |
%T | A |
|
Filter 1 |
10 |
1.0 |
1 |
2.0 |
0.1 | 3.0 |
|
Filter 2 |
20 |
0.7 |
3 |
1.5 |
0.3 | 2.5 |
|
Filter 3 |
30 |
0.5 |
50 |
0.3 |
92 | 0.04 |
These SRMs were originally specified in transmittance, the specified nominal transmittance and approximate absorbance values are given below: Certificate values are given in both %T and Absorbance.
Catalogue Number
Individual filters and Starna selected sets:
These sets allow absorbance linearity qualification over a range of values.
| Nominal % Transmittance | Nominal Absorbance | Catalogue Number | |||
| Set of 4 filters | Set of 6 filters | Set of 9 filters | Single filter | ||
| RM-4ND | RM-6ND | RM-9ND | |||
| 92 | 0.04 | • | RM-9N | ||
| 79.4 | 0.1 | RM-8N | |||
| 73 | 0.14 | • | RM-7N | ||
| 60 | 0.22 | • | RM-6N | ||
| 56.5 | 0.25 | • | • | RM-5D | |
| 50 | 0.3 | RM-5N | |||
| 40 | 0.4 | RM-4N | |||
| 30 | 0.52 | • | • | • | RM-3N |
| 25 | 0.6 | RM-2D | |||
| 20 | 0.7 | RM-2N | |||
| 10 | 1 | • | • | • | RM-1N |
| 6 | 1.22 | RM-N6 | |||
| 3 | 1.52 | • | • | RM-N3 | |
| 1.5 | 1.82 | RM-1D | |||
| 1 | 2 | • | • | • | RM-N1 |
| 0.3 | 2.52 | • | RM-D3 | ||
| 0.1 | 3 | • | • | RM-D1 | |
| 0.06 | 3.22 | RM-H6 | |||
| 0.03 | 3.52 | RM-H3 | |||
| 0.01 | 4.00 | RM-A1 | |||
Any combination of references can be ordered as a set by combining the single filter catalogue numbers.
NIST Equivalent SRM Sets
Three specifications for neutral density filter Standard Reference Materials (SRMs) are listed by NIST: SRM 930e, SRM 1930 and SRM 2930. For those users wishing to work to these specifications, sets of filters equivalent to these SRMs are available:
| Catalogue Number | |
|
SRM 930e equivalent set: |
RM-1N2N3N |
|
SRM 1930 equivalent set |
RM-N1N35N |
|
SRM 2930 equivalent set |
RM-D1D39N |
|
NIST SRM Set |
RM-SRM9ND |
Visible Spectrophotometer Qualification Set
This is a convenient way of qualifying a visible spectrophotometer for photometric accuracy, linearity and wavelength accuracy.
| Catalogue Number | |
|
Starna Transmission/Absorbance and Wavelength Set Holmium Glass Filter |
1N3N5DHG |