UV-Vis Testing Standards for Performance Verification

Thermo Scientific^™ Evolution^™ UV-Visible Spectrophotometers equipped with Thermo Scientific^™ INSIGHT^™ Software provide a reliable, user-friendly solution for pharmacopeia compliance.

Image Credit: Thermo Fisher Scientific - UV-Vis Spectroscopy

The EP and USP both specify several parameters for performance verification (PV). They evaluate absorbance accuracy, wavelength accuracy, resolution, and stray light.

Thermo Fisher Scientific has developed a summary of the alternatives available for use in PV testing, as selecting standards can be challenging. There are two kits available that incorporate the essential standards for PV testing, making the selection process easier. Standards can be ordered individually.

In this article, the particular requirements for each test will be discussed, and advice on selecting standards to complete the PV testing will be provided.

Table 1. Source: Thermo Fisher Scientific - UV-Vis Spectroscopy

Photometric (Absorbance) Accuracy

To achieve the requisite wavelength and absorbance ranges, a system's absorbance accuracy must be verified across its intended operational range.

Operational range: the absorbance range in which samples are measured in a lab, measured near the wavelength where the samples are measured.

Image Credit: Thermo Fisher Scientific - UV-Vis Spectroscopy

The Requirements

• Select at least three standards with various absorbance levels that cover the operational range.
  • For EP, it is recommended not to test > 2 A.
  • For USP, one standard must be in the 0–2 A region. If measuring > 2 A, standards evaluating this region must be selected.

Table 2. Source: Thermo Fisher Scientific - UV-Vis Spectroscopy

^*Recommended

For UV Wavelength Absorbance (< 400 nm)

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

For Visible Wavelength Absorbance (> 400 nm)

• Select at least three neutral density glass filters
  • One between 0–2 A
  • At least two more filters, depending on the operational range

Table 3. Source: Thermo Fisher Scientific - UV-Vis Spectroscopy

^*Recommended

Wavelength Accuracy

Wavelength accuracy and precision will be determined across the operational range.

Operation range: the wavelengths where samples are measured in the lab.

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The Requirements

• Use holmium oxide or mercury lamps.
• For measurements above 650 nm, didymium oxide is also necessary.
• Cerium oxide is suitable for monitoring in the far UV.

Table 4. Source: Thermo Fisher Scientific - UV-Vis Spectroscopy

^*Recommended

Mercury Lamp Options for Wavelength Accuracy

Mercury vapor lamps offer various advantages over other standards used in PV testing. These lamps emit stable atomic emission lines and are extremely well described. All low-pressure mercury lamps produce emission lines with the same wavelengths.

Mercury vapor emission spectra are used to calibrate other standards, such as holmium oxide solutions: mercury lamps never need to be recalibrated. The USP recommends atomic line spectra as the primary method for testing wavelength accuracy, 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 specifically recommends 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.”

The Thermo Scientific^™ Evolution^™ 350 UV-Vis Spectrophotometer offers an optional factory-installed mercury lamp. A mercury lamp attachment is available for the Evolution 200 series instruments as well.

Table 5. Source: Thermo Fisher Scientific - UV-Vis Spectroscopy

Resolution

What is required: To calibrate the spectrometer's resolution in the UV band, use a 0.020 % (v/v) solution of toluene in n-hexane as the reference.

Table 6. Source: Thermo Fisher Scientific - UV-Vis Spectroscopy

Stray Light

Stray light levels must be measured at the relevant wavelength(s) during performance qualification (PQ). Analysts can compare the absorbance of the specified filters to the relevant reference and record the maximum absorbance value.

Image Credit: Thermo Fisher Scientific - UV-Vis Spectroscopy

Table 7. Source: Thermo Fisher Scientific - UV-Vis Spectroscopy

Thermo Scientific Evolution UV-Vis Spectrophotometers

When meeting pharmacopeia requirements is the top priority, selecting a UV-Visible spectrophotometer should be straightforward. Each Evolution UV-Vis Spectrophotometer comes in bundles with many standard kit options:

• Thermo Scientific^™ INSIGHT^™ Security software ensures 21 CFR Part 11 compliance
• Option for an Evolution UV-Vis spectrophotometer
• Choosing a performance verification standards kit:
  • The UV-Vis Qualification Filter Kit includes all necessary standards for general instrument qualification. It contains certain standards used for pharma PV testing, but further standards will be required for overall compliance.
  • The USP and EP UV and Vis Standards Sets include all the necessary standards for general EP and USP testing.
• Thermo Scientific^™ Validator^™ paperwork for first and re-qualification throughout the instrument's lifetime

The flexible Evolution 200 series and Evolution 350 UV-Vis Spectrophotometers offer:

• INSIGHT 2 software with additional compliance features
• Precision monochromator drive ensures accurate and speedy scanning
• Double-beam optics allow for fixed or customizable 1 nm bandwidths

Table 8. Source: Thermo Fisher Scientific - UV-Vis Spectroscopy

Selecting the Evolution UV-Vis Model That Meets Your Requirements

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

The Evolution 220 spectrophotometer improves system versatility by providing a configurable bandwidth choice for a wider range of applications. This type has application-focused beam geometry that is ideal for use with integrating fiber optic probes, sphere accessories (diffuse transmittance/reflectance), and microcells.

The Evolution 260 Bio spectrophotometer enhances the Evolution 220 platform's productivity by adding the simplicity of pre-programmed bio applications.

Image Credit: Thermo Fisher Scientific - UV-Vis Spectroscopy

The Evolution 350 spectrophotometer is a high-performance solution with an extra-large sample chamber to accommodate more accessory options and a parallel beam configuration. This device features a mercury lamp option to help with pharmacopeia wavelength and bandwidth accuracy testing.

Image Credit: Thermo Fisher Scientific - UV-Vis Spectroscopy

Validated Installation

Thermo Fisher Scientific's unified lab services professionals can handle installation and provide:

• Peace of mind: Users are instructed on equipment use and routine care, and equipment is installed and set according to manufacturer specifications for optimal performance.
• Improved productivity: Accurate installation is scheduled for user convenience, optimizing performance and equipment.

Table 9. Source: Thermo Fisher Scientific - UV-Vis Spectroscopy

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 offers the option of renting standards for performance verification along with the service. Standard rental may be added to the service options listed below.

Table 10. Source: Thermo Fisher Scientific - UV-Vis Spectroscopy

Performance Verification

Table 11. Source: Thermo Fisher Scientific - UV-Vis Spectroscopy

Annual Recertification

Table 12. Source: Thermo Fisher Scientific - UV-Vis Spectroscopy

^* 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 - UV-Vis Spectroscopy.

For more information on this source, please visit Thermo Fisher Scientific - UV-Vis Spectroscopy.