Starna Scientific
  • Home
  • Cuvettes
      • Back
      • Spectrophotometer Cells
      • Colorimeter Cells
      • Fluorometer Cells
      • Cell Options
      • Special Applications
      • Cell Height Finder
      • Submit Order Enquiry
  • DMV-Bio Cell
  • Certified Reference Materials
      • Back
      • UV-Visible Spectroscopy
      • Visible Spectroscopy
      • Fluorescence Spectroscopy
      • NIR/MIR Spectroscopy
      • Raman Spectroscopy
      • Life Sciences
      • Microplate References
      • HPLC
      • Product Enquiry
  • Optics
  • Support
      • Back
      • Cells
      • Reference Materials
      • Safety Data Sheets
  • Accreditations
  • Contact Us

Menu

  • You are here:  
  • Home
  • Stray Light
  • Filter Ratio (Meilenz) Method

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

I agree

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: .

Telephone: +44 (0)20 8500 1264

Starna Scientific Ltd.
52/54 Fowler Road
Hainault, Essex
IG6 3UT
United Kingdom

Last updated 6 June 2018

 

Technique


  • UV-Visible Spectroscopy
  • Visible Spectroscopy
  • Fluorescence Spectroscopy
  • NIR Spectroscopy
  • Raman Spectroscopy
  • Life Sciences
  • Microplate References
  • HPLC

UV-VIS References


  • Instrument Qualification Kits
  • Absorbance
    • Potassium Dichromate (235-430 nm)
    • Nicotinic Acid (210-260 nm)
    • Neutral Density Filters (440-635nm)
    • Metal-on-Quartz Neutral Density Filters (250-635 nm)
    • Starna Green (Broadband SBW instruments) (250-650 nm)
    • Deep UV Reference (190-220 nm)
    • Combined Holmium/Neutral Density glass
    • Combined Didymium/Neutral Density glass
  • Wavelength
    • Holmium Oxide Liquid (240-650 nm)
    • Cerium Oxide Solution (200-300 nm)
    • Didymium Oxide Liquid (290-870 nm)
    • Combined Holmium/Didymium Solution
    • Holmium Oxide Glass (240-640 nm)
    • Didymium Glass Filter (430 nm to 890 nm)
    • Starna wide-range wavelength reference (335 – 1945 nm)
    • Starna Green (Broadband SBW instruments) (250-650 nm)
    • Deep UV Reference (190-220 nm)
    • Samarium Oxide Liquid (230-560 nm)
    • Combined Holmium/Neutral Density glass
    • Combined Didymium/Neutral Density glass
  • Stray Light
    • Specified Wavelength Method
    • Filter Ratio (Meilenz) Method
    • Stray Light Glasses
  • Resolution/Bandwith
    • Toluene in Hexane (265-270 nm)
    • Toluene in Methanol (Derivative Spectroscopy) (265-270 nm)
    • Benzene Vapour (230-270 nm)

Visible References


  • Absorbance
    • Neutral Density Filters
    • Metal-on-Quartz Neutral Density Filters (250-635 nm)
    • Starna Green (Broadband SBW instruments) (250-650 nm)
    • Combined Holmium/Neutral Density glass (360 - 640 nm)
    • Combined Didymium/Neutral Density glass (430 - 890 nm)
  • 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)

Stray Light Cut-off Filters – Filter Ratio Method

 
Purpose

Purpose

These Reference Materials can be used to qualify the stray light (or Stray Radiant Energy) of Ultraviolet (UV) spectrophotometers according to the Filter Ratio or Mielenz method. This method is described in ASTM International E 387 and is cited for instrument qualification by the US Pharmacopeia in its Chapter (Method A). This method is useful for instruments with very low stray light, such as double monochromator systems.

 
Description and Discussion

Description and Discussion

A range of cut-off filter solutions that allow stray light to be checked at a range of wavelengths from 200 nm to 390 nm. Each liquid filter is permanently sealed by heat fusion into a 10 mm high quality far UV quartz cell and a 5 mm path length cell (in the conventional 10 mm format) of the same liquid. The 5mm cell is used to provide a differential reference to the measurement of the 10 mm cell (see explanation below). Starna alkali halide stray light Certified Reference Materials are prepared in accordance with ASTM International E-387.

Stray light, also called Stray Radiant Energy or Power, is any light reaching the detector that is outside the Spectral bandwidth selected for analysis by the monochromator. It can be due to optical imperfections or stray reflections within the monochromator itself or to light leaks or other effects in the rest of the optical system. As the detector cannot discriminate between the analytical wavelength and the stray light, the stray light contributes to the detector signal and introduces an error in the measured absorption. The stray light is not absorbed even at high concentrations of the absorbing species, so its effect is a negative deviation from the linear relationship between concentration and absorbance (the Beer-Lambert law) on which most quantitative determinations are based.

Stray light is wavelength and instrument dependant. It can be present at any wavelength but is most noticeable when the energy throughput of the system at the analytical wavelength is relatively low, for example in the far UV region, and any stray light will be comparatively more significant. At these wavelengths, any deterioration in the instrument optics or UV light source will exaggerate the apparent stray light, so It is desirable to check it even if the instrument is not to be used in the far UV, as it is an excellent way of monitoring the condition of the instrument optics.

With instruments having very low stray light, such as double-monochromator systems, the Specified Wavelength method may generate very high absorbance values, requiring considerable ‘backing-off’ to achieve an on-scale reading. In the Filter Ratio, or Mielenz method, the reference materials are measured not against water, but against a 5 mm path length cell containing the same solution. This has the effect of “backing off” the measured absorbance, resulting in a direct measurement.

Typical spectra

Typical spectra

pectra obtained with a Potassium Chloride reference material using the two methods are shown below.

The differential absorbance value (ΔA) at the peak is related empirically to the Stray-Light level (s) by s = 0.25 x 10 –2*ΔA Practically, this means that an instrument exhibiting 1% stray light would give a differential absorbance value at the peak of > 0.7A. This is the instrument qualification requirement of the USP. These typical spectra were recorded on three instruments with different stray light characteristics:

Potassium-Chlo

The peak wavelength is different on each instrument due to their different stray light characteristics, but in all three cases the absorbance maximum is greater than 0.7A, so all these instruments satisfy the USP stray light requirement.

For comparison purposes, the equivalence of the two test methods is indicated in the table:

Filter Ratio Absorbance (Δ A) Specified Wavelength Absorbance (A)
0.3 1.3
0.5 1.6
0.7 2.0
1.0 2.6
1.5 3.6
2.0 4.6
2.5 5.6

An instrument giving an absorbance of >2.0 A using the Specified Wavelength method should give a differential absorbance of >0.7A using the Filter Ratio method.

Material  CONCENTRATION  Usable range Catalogue Number 

Sodium Nitrite

50 g/l aqueous

300 - 400 nm  RM-SN/5

Acetone

Spectroscopy grade

250 - 330 nm  RM-AC/5

Potassium Iodide

10 g/l  aqueous

210 - 270 nm  RM-KI/5

Sodium Iodide

10 g/l aqueous

210 - 270 nm  RM-SI/5

Potassium Chloride

12 g/l aqueous

190 - 210 nm  RM-KC/5 

 

 
Catalogue Number

Catalogue Number

 

Material  Catalogue Number 

Universal Stray Light reference set, EP and USP compliant

RM-ACKCSISN/15 

Material  Catalogue Number 

Sodium Nitrite, 10mm and 5 mm cells

RM-SN/5

Acetone, 10mm and 5 mm cells

RM-AC/5

Potassium Iodide, 10mm and 5 mm cells

RM-KI/5

Sodium Iodide, 10mm and 5 mm cells

RM-SI/5

Potassium Chloride, 10mm & 5 mm cells

RM-KC/5 
Product enquiry

Product enquiry

Data sheet

Data sheet

  • About Starna Group
  • Contact Us
  • Support
  • Environmental Policy
  • Terms & Conditions
  • Cookie Policy
  • Privacy Notice
  • Cuvettes
  • Cuvettes Catalogue
  • Reference Materials
  • CRMs Catalogue
  • Optics
  • Starna DMV-Bio Cell


The UKAS scope of accreditation, detailing the related activity, may be accessed
by clicking on the appropriate UKAS accreditation symbol

© 2022 Starna Scientific Limited