Pharmaceutical Standards for UV-Vis Spectrophotometers

Thermo Scientific™ Evolution™ UV-Visible Spectrophotometers with Thermo Scientific™ INSIGHT™ Software provide a reliable, simple-to-use solution for pharmacopeia compliance support.

The EP and USP both call out the following for parameters for performance verification (PV). They test absorbance accuracy, wavelength accuracy, resolution, and stray light.

Thermo Fisher Scientific has prepared an outline of options that are available for utilization in PV testing, as the choice of standards can be a challenge. There are two kits available which include the essential standards for PV testing to help simplify the selection process. Standards can also be purchased separately.

In this article, the individual needs for each test will be described and guidance on the selection of standards to complete the PV testing will be offered.

Table 1.

Photometric (Absorbance) Accuracy

For the wavelength and absorbance ranges required, it is necessary to verify the absorbance accuracy of a system across its intended operational range.

Operational Range = the absorbance range where you measure samples in your lab, measured near the wavelength where you measure the samples.

What is required:

• Choose at least three standards at different absorbance levels which span the measured operational range
  • For EP, it is recommended not to test >2.00A
  • For USP, one standard has to be in the 0 – 2.00A region. If measuring >2.00A, standards evaluating this region must be selected.

Table 2.

*Recommended

For UV wavelength absorbance (<400 nm)

• Choose at least three potassium dichromate standards
  • <1A 20-60 mg/L K₂Cr₂O₇
  • 1A – 2A samples: add an 80 – 140 mg/L K₂Cr₂O₇
  • 2A – 3A samples: add a 160 – 200 mg/L K₂Cr₂O₇

For visible wavelength absorbance (>400 nm)

• Choose at least three neutral density glass filters
  • One between 0-2.00A
  • At least two more additional filters depending on the operational range

Table 3.

*Recommended

Wavelength Accuracy

Wavelength accuracy and precision are to be determined across the operational range.

Operation range = the wavelengths where samples are measured in your lab.

What is required:

• Either holmium oxide or a mercury lamp
• Didymium oxide is also required if measuring at >650 nm
• Cerium oxide is recommended if measuring in the far UV

Table 4.

*Recommended

Mercury Lamp Options for Wavelength Accuracy

Mercury vapor lamps have numerous benefits over other “standards” employed in PV testing. These lamps produce atomic emission lines that do not alter, and they are extremely well characterized. All low pressure mercury lamps generate emission lines at exactly the same wavelengths.

Mercury vapor emission spectra are what other standards, like holmium oxide solutions, are calibrated against as a standard and it is never necessary to re-calibrate a mercury lamp. The USP states atomic line spectra as its first wavelength accuracy choice for wavelength accuracy testing, stating,

“This procedure is described as the primary application because the emission lines produced from a discharge lamp are characteristic of the source element and, as a fundamental physical standard; these wavelengths have been measured with an uncertainty of not more than ±0.01 nm.”

The EP also calls out atomic line spectra for this purpose, “Control the wavelength accuracy of an appropriate number of peaks in the intended spectral range… by measuring the emission from a light source for the verification of emission-line position.”

An optional factory-installed mercury lamp is available with The Thermo Scientific™ Evolution™ 350 UV-Vis Spectrophotometer. For the Evolution 200 series instruments, a mercury lamp accessory is also available.

Table 5.

Resolution

What is required: Establish the resolution of the spectrometer in the UV region by utilizing a 0.020% (v/v) solution of toluene in n-hexane with n-hexane as the reference.

Table 6.

Stray Light

As part of performance qualification (PQ), the level of stray light must be monitored at the appropriate wavelength(s). Analysts can measure the absorbance of the filters specified against the appropriate reference, and record the maximum absorbance value.

What you will need based on your operational wavelength:

Table 7.

Thermo Scientific Evolution UV-Vis Spectrophotometers

When meeting today’s pharmacopeia standards is a top priority, choosing a UV-Visible spectrophotometer should be simple.

Each Evolution UV-Vis Spectrophotometer is available in bundle packages with different standards kit choices:

• Thermo Scientific™ INSIGHT™ Security software for support of 21 CFR Part 11 Compliance
• A choice of an Evolution UV-Vis spectrophotometer
• The choice of performance verification standards kit:
  • Qualification Filter Kit for UV-Vis – Contains the standards required for general instrument qualification. Includes some standards which are used for pharma PV testing, but additional standards will be needed for total compliance
  • USP and EP UV and Vis Standards Sets – Contains all of the standards required to meet the general EP and USP testing requirements
• Thermo Scientific™ Validator™ documents for initial and re-qualification for the instrument’s lifetime

The versatile Evolution 200 series and Evolution 350 UV-Vis Spectrophotometers provide:

• INSIGHT 2 software with enhanced compliance features
• Precision monochromator drive which supplies high accuracy and quick scanning
• 1 nm fixed or selectable bandwidths with double-beam optics

Table 8.

Selecting the Evolution UV-Vis Model Which Meets Your Requirements

The Evolution 201 spectrophotometer has a 1.0 nm spectral bandwidth for high-resolution data in basic research applications and routine quality control.

With a selectable bandwidth option for a wider variety of applications, the Evolution 220 spectrophotometer enhances the versatility of a system. This model features applications focused beam geometry which is optimized for employment with integrating fiber optic probe, sphere accessories (diffuse transmittance/reflectance), and microcells.

For higher productivity in your life science laboratory to the Evolution 220 platform, the Evolution 260 Bio spectrophotometer adds the convenience of pre-programmed bio applications.

The Evolution 350 spectrophotometer is a high-performance solution that has an extra-large sample compartment for expanded accessory options and a parallel beam design. This model includes a mercury lamp option for supporting pharmacopeia wavelength and bandwidth accuracy testing.

Validated Installation

The unity lab services professionals at Thermo Fisher Scientific can handle your installation, providing:

• Peace of mind – users are trained on equipment operation and routine care, while equipment will be installed and configured to their manufacturing specifications ensuring the best performance.
• Improved productivity – accurate installation scheduled at your convenience, optimizing both user performance and equipment.

Table 9.

Validated installation includes:

• User orientation and instrument familiarization
• Installation Qualification and Operational Qualification
• On-site installation of instrument
• All engineer travel charges and labor for installation

Does not include instrument Performance Qualification (PQ)

Standards Rental Options

Thermo Fisher Scientific also provides the option to include the rental of standards for performance verification with service. Standards rental may be added to the service options below.

Table 10.

Performance Verification

Table 11.

Annual Recertification

Table 12.

* Models include Evolution Array, Evolution 60S, Evolution 200, Evolution 300 or Evolution 600 Spectrophotometers

This information has been sourced, reviewed and adapted from materials provided by Thermo Fisher Scientific – Materials & Structural Analysis.

For more information on this source, please visit Thermo Fisher Scientific – Materials & Structural Analysis.