The corresponding Chapter 2.2.25 (Absorption Spectrophotometry Ultraviolet and Visible) has not been revised in the latest version, which means that the specifications from the previous EP 10 continue to apply to Chapter 2.2.25.

1. CONTROL OF WAVELENGTH ACCURACY

EP 11:
.. requires to control the wavelength accuracy of an appropriate number of bands in the intended spectral range using one or more reference materials. It is recommended to test at least 2 wavelengths that bracket the intended spectral range!

Following reference materials (filters) are suggested:
- Holmium liquid filter for spectral range from 240 nm to 640 nm
- Didymium liquid filter for spectral range above 640 nm
- Cerium liquid filter for spectral range below 240 nm

Here you can find more information about Wavelength Filters.

2. CONTROL OF ABSORBANCE ACCURACY

EP 11:
.. requires the control of the absorbance accuracy at an appropriate number of wavelengths in the intended spectral range using solid or liquid filters. As a minimum, values at approx. the two limits of expected absorbance range should be verified

Following reference materials (filters) are suggested:
UV range: Nicotinic acid solution (Niacin) up to 2.0 Abs
Vis range: Solid filters (e.g. Neutral density glass filters) up to 2.0 Abs

* recommended wavelengths by NIST

Note:
The use of potassium dichromate filters to check the absorbance accuracy in the UV range is still possible.

Here you can find more information about Absorbance Filters.

3. CONTROL OF PHOTOMETRIC LINEARITY

EP 11:
.. requires the control of the photometric linearity in the intended spectral range.

Following reference materials (filters) are suggested:
UV range: Nicotinic acid solution (Niacin)
Vis range: Neutral density glass filters

* recommended wavelengths by NIST

Note:
To check the photometric linearity, at least 3 filters with different concentrations are required per spectral range.

Here you can find more information about Photometric Linearity.

4. LIMIT OF STRAY LIGHT

EP 11:
.. requires the control of stray light at a suitable wavelength, the acceptance criterion depends on the filter used, see table.

Following reference materials (filters) are suggested:

Here you can find more information about Stray Light Filters.

5. CONTROL OF RESOLUTION

EP 11:
.. ..requires the control of resolution with toluene in hexane and using hexane as the reference solution.

Following reference materials (filters) are suggested:
Toluene in hexane and reference solution hexane.

Here you can find more information about Control of Resolution.