Silverfingers
A week ago, we were working in the laboratory with bromhexine hydrochloride.
Identification test on chlorides was performed according to the European Pharmacopoeia.
This test includes the use of silver nitrate (AgNO3).
Silver nitrate will form a white precipitation with chlorides if chlorides are present in the molecule (here: under the form of hydrochloride, HCl).
AgNO3 + Cl- ---> AgCl ↓
As a side note: the test is then proceeded washing the precipitation with water, and then adding ammonia. Ammonia will dissolve AgCl.
Luckily for us, the test was positive.
But, after the laboratory was finished, the next day I noticed grey / black small stains on my fingers.
In the theory lessons, we've always seen that silver ions oxidize very easily forming a black/grey precipitation, metallic silver. Thus working with silver ions should be done in absence of light, which could catalyze the oxidation reaction.
Ag+ --> Ag↓
What happened was that during the test, I probably got some exposure of AgNO3 on my skin which resulted in small stains. After washing my fingers, trying to scrub it off, nothing worked, patience is key!
Luckily the silver will form in the dead layer of the skin, which means that after some weeks, the layer will fall off and new cells will take its place, which means the silver will also come off.
Below are some pictures of the silver formation, some of it came loose when scrubbing, but these pieces are stubborn!
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| Small stain on the left middle finger |
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| Small stains on the left thumb |
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| Stains of silver on the right middle finger |
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