Our UV/vis Spec. measurements are no longer repeatable, after a minute or two the absorbance of the same solution in the same cuvette changes significantly. Sometimes the absorbance is zero or even negative. Is it the light source or the detector?
Our Spec. is an archaic WPA S2000 model with a D2/tungsten S2000L light source, and I don't know exactly when the lamps have been replaced.
The lamp model is Deuterium J05, and I couldn't find the same part in the country, but I hope I can replace it with a similar one. Do you know if there is a model that can be inserted instead?
You can try this website or buy a 'new' spec'
http://www.ebay.com/itm/WPA-S2000-Lightwave-UV-VIS-spectrophotometer-Diode-Array-/301936217530
I do not understand that such an unlawful machine, which does not obey the Lambert-Beer's Law, has been used recently among Biochemists. Photometric assay gives 4-fold lower values as compared to HPLC values (please see the Fig. 10 in file "SEC fucoidan determination").
By the way, if you wish the micro and sensitive determination of DNA and/or RNA, please try our recently published HPLC-SEC-polysaccharide analysis method (please see file, SEC fucoidan determination). This HPLC-SEC method seems to be applicable also to the biotechnological preparation of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) micro-determination.
The best would be to ask it to WPA S2000 supplier. Then, look at lamp specifications. Afterwards you can try with the same supplier for a similar lamp or any other famous spectrophotometer suppilers (Shimadzu, ThermoSientific and so on).
Fortunately deuterium lamps is one of the most common consumables in spectroscopy.
I have searched for pulsed deuterium lamps in vain, and pulsed xenon lamp is present. Deuterium lamp can not be used in visible light, and is used for UV detection. Pulsed xenon lamp seems to be like a sun-light, and can be used as UV/VIS detection. Then, you should buy pulsed xenon lamp ?
Hamamatsu Photonics K.K. (Hamamatsu, Shizuoka, Japan) produces and deals many kinds of lamps,,,
https://www.hamamatsu.com/us/en/1001.html
By the way, Mr. Kenjiro Takayanagi (Hamamatsu Photonics Co.) has firstly invented television in 1926.
Thank you very much Dr Hayakawa. I inquired of the supplier about the possibility of replacement with Xenon lamps, and they said it requires different electronic control and supply requirements.
I feel very sorry that you are forced to do the work with a cheap machine. However, I think you can declare that you should do the work with reliable photometer.
By the way, direct application of photometer is very dangerous, since it does not obey the Lambert-Beer Law due to without purification. Thus, photometric assay gives 4-fold lower values as compared to HPLC values (please see the Fig. 10 in the above file "SEC fucoidan determination").
Then, I would recommend HPLC-photometric method to perform your important work.
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