ASTM E387-04(2022) PDF
Standard Test Method for Estimating Stray Radiant Power Ratio of Dispersive Spectrophotometers by the Opaque Filter Method
Standard Test Method for Estimating Stray Radiant Power Ratio of Dispersive Spectrophotometers by the Opaque Filter Method
- Статус документа:
- Действующий
- Формат:
- Электронный (PDF)
- Количество страниц:
- 11
- Дата публикации:
- 1 ноября 2022 г.
- Издание:
- E387
- ICS:
- 17.180.30
SIGNIFICANCE AND USE 5.1 Stray radiant power can be a significant source of error in spectrophotometric measurements. SRP usually increases with the passage of time; therefore, testing should be performed periodically. Moreover, the SRPR test is an excellent indicator of the overall condition of a spectrophotometer. A control-chart record of the results of routinely performed SRPR tests can be a useful indicator of need for corrective action or, at least, of the changing reliability of critical measurements. 5.2 This test method provides a means of determining the stray radiant power ratio of a spectrophotometer at selected wavelengths in a spectral range, as determined by the SRP filter used, thereby revealing those wavelength regions where significant photometric errors might occur. It does not provide a means of calculating corrections to indicated absorbance (or transmittance) values. The test method must be used with care and understanding, as erroneous results can occur, especially with respect to some modern grating instruments that incorporate moderately narrow bandpass SRP-blocking filters. This test method does not provide a basis for comparing the performance of different spectrophotometers. Note 8: Kaye (3) discusses correction methods of measured transmittances (absorbances) that sometimes can be used if sufficient information on the properties and performance of the instrument can be acquired. See also A1.2.5. 5.3 This test method describes the performance of a spectrophotometer in terms of the specific test parameters used. When an analytical sample is measured, absorption by the sample of radiation outside of the nominal bandpass at the analytical wavelength can cause a photometric error, underestimating the transmittance or overestimating the absorbance, and correspondingly underestimating the SRPR. 5.4 The SRPR indicated by this test method using SRP filters is almost always an underestimation of the true value (see 1.3). A value cited in a manufacturer’s li... SCOPE 1.1 Stray radiant power (SRP) can be a significant source of error in spectrophotometric measurements, and the danger that such error exists is enhanced because its presence often is not suspected (1-4).2 This test method affords an estimate of the relative radiant power, that is, the Stray Radiant Power Ratio (SRPR), at wavelengths remote from those of the nominal bandpass transmitted through the monochromator of an absorption spectrophotometer. Test-filter materials are described that discriminate between the desired wavelengths and those that contribute most to SRP for conventional commercial spectrophotometers used in the ultraviolet, the visible, the near infrared, and the mid-infrared ranges. These procedures apply to instruments of conventional design, with usual sources, detectors, including array detectors, and optical arrangements. The vacuum ultraviolet and the far infrared present special problems that are not discussed herein. Note 1: Research (3) has shown that particular care must be exercised in testing grating spectrophotometers that use moderately narrow bandpass SRP-blocking filters. Accurate calibration of the wavelength scale is critical when testing such instruments. Refer to Practice E275. 1.2 These procedures are neither all-inclusive nor infallible. Because of the nature of readily available filter materials, with a few exceptions, the procedures are insensitive to SRP of very short wavelengths in the ultraviolet, or of lower frequencies in the infrared. Sharp cutoff longpass filters are available for testing for shorter wavelength SRP in the visible and the near infrared, and sharp cutoff shortpass filters are available for testing at longer visible wavelengths. The procedures are not necessarily valid for “spike” SRP nor for “nearby SRP.” (See Annexes for general discussion and definitions of these terms.) However, they are adequate in most cases and for typical applications. They do cover...
Abstract
Overview
ASTM E387-04(2022), developed by ASTM International, establishes a standard test method for estimating the Stray Radiant Power Ratio (SRPR) of dispersive spectrophotometers using the opaque filter method. Stray radiant power (SRP) is a significant source of photometric error in spectrophotometric measurements, potentially impacting accurate readings of absorbance and transmittance. This standard provides a controlled procedure to estimate the proportion of radiant power at undesired wavelengths within a spectrophotometer-an important indicator of instrument condition and measurement reliability.
Key Topics
- Stray Radiant Power (SRP): Unintended light at wavelengths different from the selected analytical wavelength that can interfere with spectrophotometer measurements.
- Opaque Filter Method: Use of test filters with high absorption (very low transmittance) in certain wavelength regions to assess the extent of stray light.
- Instrument Performance Monitoring: SRPR measurement as a practical indicator for ongoing equipment performance, reliability, and the need for maintenance.
- Spectral Ranges: The method covers testing in ultraviolet (UV), visible, near-infrared (NIR), and mid-infrared (MIR) ranges for instruments of conventional design.
- Limitations and Scope: The test is not universally sensitive, especially for very short wavelengths in the UV or low frequencies in the IR, and does not support direct comparison among different spectrophotometers.
Applications
- Routine Instrument Verification: Periodic SRPR testing tracks instrument drift or age-related degradation, supporting preventative maintenance and ensuring consistent measurement accuracy.
- Quality Control: Maintaining a control chart of SRPR results helps identify reliability shifts, signaling when corrective actions are required.
- Regulatory and Compliance Requirements: Some analyses-particularly in regulated or quality assurance environments-demand the monitoring of stray radiant power as part of method validation and equipment qualification.
- Analytical Accuracy: By identifying wavelength regions suffering from high stray light, laboratories can avoid misleading absorbance or transmittance values, reducing analytical errors.
- Method Adequacy Verification: The standard outlines procedures appropriate for most typical laboratory spectrophotometers, helping analysts verify their instrument’s suitability for critical work.
Related Standards
- ASTM E131: Provides terminology related to molecular spectroscopy referenced throughout ASTM E387.
- ASTM E275: Describes methods for measuring and describing the performance of ultraviolet and visible spectrophotometers, and is particularly relevant when calibrating grating instruments with SRP-blocking filters.
- Broader Context: ASTM E387 conforms to internationally recognized standardization principles as established by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Practical Value
- Early Error Detection: Regular use of this test method allows laboratories to detect problems related to stray radiant power before they affect data quality.
- Instrument Benchmarking: Establishes a baseline performance metric for newly installed equipment or after major service, enhancing confidence in spectrophotometric results.
- Non-intrusive Testing: The method uses readily accessible filters and standard instrument operations, making it suitable for most laboratories without extensive modifications.
- Supports Method Validation: Demonstrates that analytical data are unaffected by excessive stray light, supporting method robustness and laboratory accreditation requirements.
Maintain the accuracy and reliability of your spectrophotometric measurements with periodic SRPR testing as outlined in ASTM E387-04(2022), safeguarding analytical integrity across research, quality control, and compliance-driven environments.
Keywords: ASTM E387, stray radiant power ratio, SRPR, spectrophotometer calibration, stray light test, opaque filter method, instrument verification, laboratory quality control, photometric error prevention, UV-Visible spectroscopy standards.
Технические детали
- Технический комитет
- E13 - Molecular Spectroscopy and Separation Science
- SKU
- ASTM E387-04(2022)
Похожие стандарты
Другие стандарты ASTM
ASTM-TPT-47
Phase I & Phase II Environmental Site Assessment Processes
Phase I & Phase II Environmental Site Assessment Processes
ASTM-TPT-8
Phase I Environmental Site Assessment Practices For Commercial Real Estate: Phase I Site Assessment & Transac…
ASTM-TPT-1137
ASTM D975 Standard Specification for Diesel Fuel
ASTM D975 Standard Specification for Diesel Fuel
ASTM-TPT-1202
ASTM D8421 Standard Test Method for Determination of Per- and Polyfluoroalkyl Substances (PFAS) in Aqueous Ma…
ASTM D8421 Standard Test Method -- eLearning Course
ASTM-TPT-691
Microaprendizagem para D4057: Amostragem de ponto (PT)
D4057 Microlearning: Spot Sampling Portuguese
ASTM-TPT-1091
Metodo de prueba estandar D4052 de ASTM -- Curso de aprendizaje electrónico (ES)
Modulo eLearning para ASTM D4052 en espanol
ASTM ACEM20180086
Using Neutron Radiography to Quantify the Settlement of Fresh Concrete
Specifications have been implemented for concrete bridge decks in North America that restrict the use of higher slump concrete mixtures primarily because of concerns about differential settlement and…
ASTM ACEM20180041
Experimental Study of Competing Failure of Reinforced Concrete Based on the Weibull Distribution
To predict the failure lifetime of reinforced concrete, a current accelerating corrosion test was performed on concrete by simulating the environment in an area with saline soil. To study the concret…