hello
I am using Arnow test for Catechol detection: 1ml HCL 5N + 1ml de nitrite reagent (10g of sodium Nitrite 10g molybdate sodium in100ml) + 1 ml of suprenant + 1 ml of NaOH 1M +1ml d'H2o I have the color yellow with the formation of bubbles
What does it mean ? I have a positive result
I have the feeling that something went wrong, but it doesn't mean your assay is negative.
You used too much HCl I'm afraid. The Arnow methodology uses 1 ml HCl 0.5N, not 5N. The first color you get after the addition of the nitrite reagent is the correct one (yellow), but after the addition of NaOH, it should turn to red. It doesn't, because the NaOH that you added is not enough to make the solution alkaline (excess of HCl).
I have the feeling that something went wrong, but it doesn't mean your assay is negative.
You used too much HCl I'm afraid. The Arnow methodology uses 1 ml HCl 0.5N, not 5N. The first color you get after the addition of the nitrite reagent is the correct one (yellow), but after the addition of NaOH, it should turn to red. It doesn't, because the NaOH that you added is not enough to make the solution alkaline (excess of HCl).
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