Hi to all
I am writing you in order to get more information about the procedure 3.2.1 on Arsenic determination in glass containers for pharmaceutical use. In the monograph, at the paragraph ”Reference solutions” it is reported:
“Prepare the reference solutions using arsenic standard solution (1 ppm As) R. Add 10 ml of hydrochloric acid R and 5 ml of 200 g/l solution of potassium iodide R. Heat on a water-bath at 80 °C for 20 min, allow cool and dilute to 100.0 ml with water R. The concentration range of the reference solutions is tipically 0.005 – 0.015 ppm of As.”
I am wandering how to execute the test. Should I have to react the 1ppm As standard and then dilute it to obtain the required reference solutions, or should I have to react 3 differently concentrated solutions in order to obtain the 3 reference standard solutions? thank you all for you concern.
The arsenic determination is done on Hydride generation atomic absorption spectrometry. The reaction with potassium iodide is probably to oxidate arsenic to its oxide (As2O3) and then to react with the hydrogen to make volatile gas AsH3 - arsine and measure.
The safest approach would be to prepare three different standard solutions and then react them with potassium iodide.
The dilution of the standard after reaction will probably need to take the consideration of the formula of arsenic oxide when calculation is done in molar concenration at some point. When measurment and calculation is done in concentration of As molecular formula of arsenic oxide should not be a problem.
Hi Antonio .. I understand that one need to prepare multiple standards with varying concentration between 0.005 ppm to 0.015 ppm of As and then react them with KI....
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