For a UV Vis spectrophotometer stray light test and resolution power test failed.
Can I used it normally or there is some problem in performance and results given by it.
Which type analysis affected due to these two test failure of spectrophotometer.
If there is error then what is the error factor and how I will calculate it for it.
For example for stray light its value is 1.64. It is less than 2( required value for passing the test).
For resolution power its value is 1.419. For passing the test it must be above 1.5.
Don't use it! Use the acceptance criteria listed in your SOP. It is the instrument's manufacturer who must meet these criteria or better.
1 nm one way or another (wavelength accuracy) will not materially affect your results particularly if your method is not just using a standard as a reference but also in your calculations.
Increased stray light will cause increased curvature in calibrations as A increases.
Resolution is critical only in the few tests where you need to discriminate between closely spaced wavelengths.
If my understanding of your question is correct, your instrument did ot respect the specifications given by the manufacturer... but I do not underdtand exactly the meaning of the numbers you give.
Stray light can have 2 different origins
- Leak of light entering your instrument by any part of its structure. That can be verified and corrected by using an external punctual source (optical fiber) and scanning the all instrument.
- Multiple refection of e.g. the zero order of diffraction inside your instrument... That can be wavelength dependent. Multiple reflections can be corrected by introducing extra baffle (black painted) inside the instrument.
Spectral resolution can be altered by a bad alignment of the instrument
-- Bad position of the grating(s) in terms of focal distance for example.
An other parameter you can use is the FWHM (at different wavelengths) this parameter gives you the full wide at mean high of a single line emitted by a laser or selected lines emitted by a hollow cathode source.
I hope these few indications can help you to solve your problem..
Dr. Didier Gillotay
Thanks all of you for your sincere response for my question.
Actually I go through the calibration of Shimadzu 2450 UV-visible Spectrometer and for the five calibration test it passes only 3 tests.
1.Wavelength Accuracy Measurement Test
2.Control of Absorbance
3.Stray light limit test
4.Resolution Power
5.Linearity with caffein
It passes for 1,2 and for 5 number tests and failed for 3 and 4 test.
For Stray light limit test I used 1.2% w/v solution of KCI for passing the test Spectrometer must show the Absorbance not less than 2 at 200 nm but it shows always below 2.
For resolution power test I used 0.02% v/v Toluene in Hexane and check Absorbance at 269 and 266 nm. The ratio of Absorbance at 269 / 266 nm must be not less than 1.5 but it shows below 1.5.
So I want to know for which type of tests I can't use this Spectrometer and if I used what are the error factors.
Obviously 3 and 4 since they didn't pass. Do they matter with respect to methods you use? Did you filter the solutions before tests 3 and 4?
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