Wavelength accuracy test

Esquivel, J. B., Wavelength accuracy testing of UV-visible detectors in liquid chromatography, Chromatogmphia, 26, 321, 1988. 

FIGURE 6 Automated 205/273 nm wavelength stepping results for wavelength accuracy test, using caffeine standard solution. Courtesy of PerkinElmer LAS, Shelton, CT. 

Wavelength accuracy tests conducted using appropriate external standards will prevent potential problems that could occur with proprietary internal calibration protocols. The exact nature of any calibration standard must be noted in a validation protocol. Rare earth oxides and glass standards are candidates for such calibration. 

Waters Symmetry CIS (150x3.9 mm i.d., 5 pm) used in most tests except wavelength accuracy and compositional accuracy tests. 

Experiment 4 is intended to check the detector s wavelength accuracy at 205nm and 273nm. Using the same caffeine solution as for the OQ test, this test is performed and calculated as in the procedure described earlier under subsection (i) of Detector in section (j) of the OQ guidelines. 

It is recommended that OQ test the following on an HPLC system flow accuracy, pump compositional accuracy, pressure pulsations, column oven temperature accuracy/stability, detector noise/drift and wavelength accuracy, autosampler injection precision and carryover. 

The protein analyzer tests response linearity (absorbance/fluorescence), wavelength accuracy and UV linearity, dynamic noise, drift, and the zero offset. 

The performance verification tests required by major pharmacopoeias for UV-Vis spectrophotometers are listed in Table 10.1 [1-4]. The required performance tests include wavelength accuracy, stray light, resolution, and photometric... 

If a system comprises several modules, it is recommended that system tests be performed for parameters that are affected by multiple modules (holistic testing) rather than performing tests module by module (modular testing). Individual module tests should be performed if the parameter is affected by that module only (e.g., the wavelength accuracy of an HPLC variable-wavelength detector or the temperature accuracy of a column compartment). 

A frequently discussed question is whether either system suitability testing or the analysis of QC samples are sufficient to prove ongoing system performance, or whether additional checks should be performed. The answer to this question depends very much on the conditions under which the control samples are analyzed. For example, if the system is used for trace analysis and the amounts of the control sample do not include trace-level amounts, the capability of the system to measure low amounts should be verified. In HPLC, this could be a routine check of the wavelength accuracy, the baseline noise, and the intensity of the UV lamp. System suitability checks and control sample analysis are sufficient as PQ checks if all critical system parameters are checked as part of tests and evaluations. 

Table 20-1 gives the absorbance of a solution that you can prepare to test the accuracy of absorbance measurements on your spectrophotometer. Absorbance accuracy is affected by all components of the spectrophotometer, as well as stray light. Standards are also available to measure wavelength accuracy.9... 

Calibration of balances calibration of ultraviolet grating for wavelength accuracy exchange of lamps system suitability testing analysis of quality control samples and evaluation of results using control charts. 

Operational qualification, or acceptance testing, is the process of demonstrating that the whole instmment or its modules will function according to its operational specification, in the selected environment, according to previously defined functional and performance specifications ( acceptance criteria ). This procedure can be performed to the extent of the self-diagnostics routine test or to a more detailed procedure regarding flow-rate, injector precision, or wavelength accuracy. It can be carried out by the user or the vendor on behalf of the user. 

It is suggested that instrument qualification be performed every 6 months or following major repairs or optical reconfigurations. Qualification tests include wavelength accuracy, absorbance scale linearity, and high- and low-light flux noise tests. 

The parameters to be tested in OQ/PV for capillary electrophoresis are temperature stability, voltage stability, injection precision, detector performance (noise, drift and wavelength accuracy), and integrator functionality. Additionally, the migration time of a test analyte, using a well-defined method, may be monitored as an indication of the overall function of the instrument. Where the test procedure is performed using a test analyte and method, the usual validation parameters of the... 

The technical specifications identified and described by most of the manufacturers of absorption photometers for medical use include wavelength accuracy, spectral half-width of spectral radiation flux at the detector, photometric accuracy, percentage of wavelength integrated, false radiation, and photometric short-time repeatability. As discussed previously [2], the Instrumental Performance Validation Procedures, issued by serious manufacturers of analytical instruments, indicate the methods and the reference materials required to test and to maintain optimum spectrometer performance in daily routine analysis. 

To verify that a spectrophotometer is performing satisfactorily, the device must be shown to be able to operate within the specifications provided for it. Parameters to be tested include (1) wavelength accuracy, (2) spectral bandwidth, (3) stray light, (4) linearity, and (5) photometric accuracy. 

Test for detector noise (Section 25.5.) immediately after the test sequence. Determination of the wavelength accuracy of the detector (Section 25.5). Registration of the gradient profile (Section 25.4). 

Anthracene solution, for the test of the wavelength accuracy 9.5-10.5 mg anthracene p.a. is dissolved to 100 ml. 1 ml of this solution is dissolved to 100 ml with MP 1, giving a concentration of approx. 1 pgml... 

If the detector has a built-in holmium oxide filter the wavelength accuracy is tested with this filter in accordance to the manufacturer s test procedure. 

The wavelength uncertainty test verifies the accuracy and precision of the spectrophotometer x-axis. Typically, the x-axis will be in nanometers for a dispersion instrument and cm for a FT instrument. The use of cm for the spectral axis of an FT instrument is due to the mathematics of the interference term (Atkins 1996). The wavelength standards have stable isolated peaks usually based on a mixture of rare-earth oxides. The center of mass of the peaks is compared to standard values established on master instruments at National Institute of Standards and Technology (NIST). The typical tolerance values for the peak accuracy are 1 nm [19]. The observed precision values are usually much smaller than 1 nm due to the high reproducibility of modern spectrophotometers. The photometric linearity verifies that the y-axis of the spectrophotometer is linear over a typical refiectance range. The linearity is verified by scanning a series of standards of known reflectance (absorbance) values. The measured absorbance is plotted versus the standard values. The USP chapter specifies that the slope of this curve is equal to 1.0 0.05 with an intercept of 0.0 0.05. Photometric standards are available from instrument vendors and third party suppliers. 

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