How to Conduct a Colorimetric Test for Artesunate Tablets
(GREEN MD, MOUNT DL, WIRTZ RA, WHITE NJ. A Colorimetric Field Method to Assess the Authenticity of Drugs Sold as the Antimalarial Artesunate. Journal of Pharmaceutical and Biomedical Analysis 24:65-70, 2000.)
Items Required
- 100 mg Fast Red TR salt
- 20 ml sodium hydroxide (NaOH) 1 N
- 40 ml acetic acid 1.1 M
- 20 ml distilled water
- Scalpel blades and gloves
- Clean tubes, 5-10 ml volume
- Droppers or pipettes for dispensing 0.5-1.0 ml
- Test tube rack
- Genuine artesunate tablet for positive control
- Prior to testing, dissolve 100 mg Fast Red TR salt in 20 ml of distilled water. The above reagents are sufficient to do ~40 tests.
- Reagents can be stored at room temperature. Wrap the tubes containing Fast Red TR salt and solution in aluminum foil to protect from light.
- Please note that the chemicals are potentially dangerous:
- Wear gloves
- Keep out of reach of children
- Fast Red TR salt is an irritant and potentially mutagenic
- Sodium hydroxide is a strong base and will cause burns
- Dispose of the used chemicals safely after each test
Method
Test a positive control, using a known genuine artesunate tablet, and a negative control (blank, no artesunate) at each session. This is to check that the test is working correctly.
- Scrape ~ 1% of the test 'artesunate' tablet into a clean tube and label with test number.
- Scrape ~ 1% of the positive control artesunate tablet into a clean test tube and label as '+ control'.
- Leave a third clean tube empty and label as '- control'.
- Add 0.5 ml 1N NaOH to all tubes and shake gently (you should at least have 3 tubes, more if you are testing more than one suspect tablet).
- Wait for at least 5 minutes. Some fragments of the tablets may not dissolve–this does not matter.
- Add 1 ml of 1.1M acetic acid to all tubes and shake gently.
- Add 0.5 ml of the Fast Red TR salt solution to all tubes and shake gently.
- Wait 5 minutes.
- If the solution turns yellow the tablet contains artesunate. If the solution remains colorless the tablet does not contain artesunate.
- In order to interpret the test of the suspicious tablet, the positive control must turn yellow and the negative control MUST remain colorless. If this does not occur, repeat test.
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