Tools for Easier Compliance

The regulations for ultraviolet and visible spectroscopy were recently updated by the US and European pharmacopoeias. The revised US Pharmacopeia (USP) Chapter became mandatory on 1st December 2019. European Pharmacopoeia 10.0 (EP) Chapter 2.2.25 became mandatory on 1st January 2020. Both standards now require absorbance linearity to be qualified and that qualification measurements are made at parameter values that match or ‘bracket’ those used for analysis. This may well mean that a single reference for e.g. stray light will no longer suffice and explains why potassium chloride solution, for example, is no longer a universal stray light reference but is recommended for the far UV. It also means that it is no longer possible to specify universal ‘kits’ that can qualify instruments for all applications.

The Basic Qualification Kits described below, however, will meet the routine needs of many laboratories and can be supplemented with additional references if required. Starna CRM kits offer cost savings when compared to the purchase of individual references.

Basic Qualification Kits

The kits below will allow instrument qualification over the stated wavelength and absorbance ranges for compliance with EP 2.2.25 and USP . References are provided to qualify wavelength accuracy, absorbance accuracy and 3-point linearity, stray light and resolution/bandwidth.

The stray light references for USP compliance are for Chapter Method <857> B. Note that Potassium Chloride solution is included in all the basic kits as even if the instrument is not being used in the far UV, increasing stray light at this wavelength (200nm) is a sensitive indication of deterioration of the instrument optics.

These kits have been designed to qualify UV-visible spectrophotometers over the wavelength and absorbance ranges commonly used in pharmaceutical analysis. If your operating parameters fall outside these ranges, Starna has the world’s biggest range of spectroscopy CRMs and will be pleased to recommend additional or alternative references to meet individual requirements. For more information see Selecting References for Compliance - a User Guide or contact sales@starna.com for advice.

Basic Kit for EP 2.2.25 compliance
Catalogue number: RM-EP20
[Kit identity: RM-020610HLKCSIKISNTX

Reference To qualify Wavelength range
Holmium cell Wavelength accuracy 240 - 650 nm
Potassium dichromate 20, 60 & 100 mg/l & blank cell. Absorbance accuracy and linearity, 0-1 A 235 – 350 nm
Potassium chloride Stray light, 200nm 200 -370 nm
Sodium iodide Stray light, 220 nm 200 -370 nm
Potassium iodide Stray light, 250 nm 200 -370 nm
Sodium nitrite Stray light, 340, 370 nm 200 -370 nm
Toluene in hexane Resolution (bandwidth), 265-270nm 265-270 nm

 

Basic kit for USP Chapter <857compliance
Catalogue number RM-USP20
[Kit identity RM-02061060HLKCKIACSNTX]

Reference To qualify Wavelength range
Holmium cell Wavelength accuracy 240 - 650 nm
Potassium dichromate 20, 60 & 100 mg/l & blank cell. Absorbance accuracy and linearity, 0-1 A 235 – 350 nm
Potassium dichromate Absorbance accuracy, 1 A 430 nm
Potassium chloride Stray light, 200nm 240 -370 nm
Sodium iodide Stray light, 220 nm 240 -370 nm
Potassium iodide Stray light, 250 nm 240 -370 nm
Acetone Stray light, 300 nm 240 -370 nm
Sodium nitrite Stray light, 340, 370 nm 240 -370 nm
Toluene in hexane Resolution (bandwidth), 265-270nm 265-270 nm

 

Basic kit for USP and EP compliance 
Catalogue number RM-USPEP20
[Kit identity RM-02061060HLKCKIACSNTX]

Reference To qualify Wavelength range
Holmium cell Wavelength accuracy 240 - 650 nm
Potassium dichromate 20, 60 & 100 mg/l & blank cell. Absorbance accuracy and linearity, 0-1 A 235 – 350 nm
Potassium dichromate Absorbance accuracy, 1 A (USP) 430 nm
Potassium chloride Stray light, 200nm (EP & USP) 240 -370 nm
Sodium iodide Stray light, 220 nm (EP) 240 -370 nm
Potassium iodide Stray light, 220 nm (USP), 250 nm (EP) 240 -370 nm
Acetone Stray light, 300 nm (USP) 240 -370 nm
Sodium nitrite Stray light, 340 nm (EP & USP), 370 nm (EP) 240 -370 nm
Toluene in hexane Resolution (bandwidth), 265-270nm 265-270 nm

 

Far UV extension kit - EP and USP compliance  
Catalogue number RM-06A12A24ARE

Reference To qualify Wavelength range
Cerium cell Wavelength accuracy 200 - 270 nm
Nicotinic acid 6, 12 & 24 mg/l Absorbance accuracy and linearity, 0-1 A 210 – 270 nm

 

Visible Absorbance and Wavelength kit   
Catalogue number RM-1N3N5DHG

Reference To qualify Wavelength range
Holmium Filter Wavelength accuracy 240 - 640 nm
Neutral Density Filters, 0.25, 0.50 & 1.00A Absorbance accuracy and linearity, 0-1 A 440 – 635 nm

Note: the Pharmacopoeias do not require stray light qualification above 400 nm.

Owners of earlier kits can easily upgrade to the new standards with additional or alternative references. In such cases, depending on your quality protocols, you may consider having the amended kit recalibrated at the same time as the new references to preserve the recalibration date.

 

Other Kits

Absorbance Linearity sets:

Potassium Dichromate linearity sets: a selection of solutions for qualifying UV absorbance linearity up to 3.5A (235 – 350 nm & 430nm)
Nicotinic Acid Linearity Set: Far UV absorbance linearity up to 1A (210 – 270 nm)
Starna Green Linearity Set: UV and visible absorbance linearity up to 1A (250 – 650 nm)
Neutral density filter sets: visible absorbance qualification up to 3A

NIST equivalent sets:

NIST has published specifications for absorbance filter Standard Reference Materials (SRMs). These filter sets are equivalent to these SRMs:
NIST equivalent Neutral Density sets: equivalent to NIST SRMs 930e, 1930 and 2930.
NIST equivalent Metal-on-Quartz set: equivalent to NIST SRM 2031a

Stray light filter sets:

Universal Stray Light reference set, Specified Wavelength method: USP and EP compliant

Stray Light reference set, Filter Ratio method: USP compliant, recommended for low stray light instruments