Bühne

European Pharmacopoeia EP 11, Chapter 2.2.25

The latest version of the European Pharmacopoeia (EP 11), applies from 01 January 2023

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.

Requirements in EP 11, Chapter 2.2.25

The EP 11-compliant control of the UV/Vis spectrophotometer depends on the intended spectral range (absorption and wavelength range).

Important Statements in the EP 11, Chapter 2.2.25

„.. quantitative measurements relying on absorbance values above 2.0 should be avoided“
„..all measurements are carried out with reference to the same solvent or the same mixture of solvents (blanks)."

Following parameters should be regularly controlled:

1. Wavelength accuracy
2. Absorbance accuracy
3. Photometric linearity
4. Limit of stray light
5. Resolution


Requirements of EP 11 Chapter 2.2.25

The requirements of EP 11 are briefly explained in the following context

 

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

Material Wavelength (nm)
Cerium liquid filter 201, 211, 223 ,240, 254
Didymium liquid filter 512, 732, 794
Holmium liquid filter 241, 287, 361, 451, 485, 537, 640

 

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: Neutral density glass filters up to 2.0 Abs

Material Wavelength (nm)
Niacin liquid filter 213, 261
Neutral density glass filter (440, 465, 546.1, 590, 635)*

* 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

Material Wavelength (nm)
Niacin liquid filters (5 - 40 mg/l) 213, 261
Neutral density glass filters (440, 465, 546.1, 590, 635)*

* 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:

Filter / Solution Absorbance at Wavelength
Potassium chloride (12 g/L) ≥ 2.0 Abs at 198 nm
Sodium iodide (10 g/L) ≥ 3.0 Abs at 220 nm
Potassium iodide (10 g/L) ≥ 3.0 Abs at 250 nm
Sodium nitrite (50 g/L) ≥ 3.0 Abs at 340 and 370 nm

 

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.

Contact/Inquiry

Hellma USA Inc.
120 Terminal Drive
11803 Plainview, NY
United States

Phone: +1 5169 3908 88
info.us@hellma.com
http://www.hellmausa.com

Contact/Inquiry

Disabled, please use email.