I have tried to determine selenium in UV-Vis Spectrophotometer by using Methylene blue but it is very sensitive to time with in 30-60 sec i hv to measure and after that the color is vanished. so kindly suggest some method to be used to determine selenium (below 30ppb) in UV Vis Spectrophotometer.
It sounds like the reduction rate is too fast. Have you tried modifying he conditions to slow the reaction, e.g., decreasing the concentration of selenate?
By the way, my Google search mentions 'methylene blue'.
Using such a method you will have to check some results against a direct estimate of selenate and I'd suggest that you do so early in the study in case you find a problem
let me search how to reduce concentration using surfactants Reem A. Al-Luhaiby
Sorry its methylene blue and I have tried this, but within 30-60 sec colour degraded... can't get accurate results Paul Milham
Hello Pallavi,
I expect that Reem means 'dilute the concentration', i.e., both he and I are suggesting that you test whether the reaction rate is too fast because the Se concentration is too high.
Please try and let us know what happens, Paul.
What is the published working range? If you are well below it then either you gave Se contamination or an interference.
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