Problems with the spectrophotometer
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The 722S visible spectrophotometer (Shanghai Jingke) allows the transmittance to be adjusted to 100% or 0% stably when no blank sample is used; however, when a blank sample is used, 0% can be set, but 100% keeps increasing gradually. (After setting 0%, the cover is closed and 100% is adjusted, then the cover is opened to adjust back to 0%, and once the cover is closed again, the transmittance remains above 100% and continues to rise – the same issue occurs even after re-adjustment.) The wavelength used is 620nm. Could anyone explain why this happens? (The instrument should be preheated for 20 minutes). The reagent used in the experiment to determine calcium and magnesium in saline is hydroxynaphthol blue (HNB).
The blank area may contain bubbles or be cloudy
Check other samples in the same spectrophotometric reagent for any abnormalities, and examine whether there are any mistakes in the reagents used or in the procedures followed
I’m currently learning about this; I hope to see the correct answer. The model we purchased is 721, and it’s also from Shanghai Jingke.
There might be an issue with the wavelength you selected
There’s a problem with the wavelength you selected
There might be an issue with the wavelength you selected
Preheat it for 0.5–1 hour first, then set it to 100; the light source should be fine. The issue mentioned by the poster is most likely something like a solution adhering to the outer wall of the cuvette. Wash the cuvette clean or try using a new one
Regarding the issue of light sources mentioned upstairs, I would like to ask: If the instrument’s self-check indicates that the energy of the deuterium lamp is low, does it affect the test results? What is the wavelength range of the influence?
Reply 1# congliang: It’s probably because there are bubbles inside the cuvette, or the cuvette wasn’t cleaned properly. The outer surface of the cuvette should be wiped using specialized lens cleaning paper, haha