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Tricaine methanesulfonate (MS-222) Guidelines

APLAC “Guidelines for the Use of Tricaine Methanesulfonate  (MS-222) in Aquatic Animals”. 

Please review this guideline with all applicable lab members.

  1. When working with powder during solution preparation, always work in a laboratory fume hood, and wear a lab coat, safety glasses (or safety goggles + face shield if splash potential exists), and nitrile gloves. If preparation is not conducted in a laboratory fume hood, consult with EH&S’s Occupational Health & Safety Program regarding the requirement for respiratory protection by calling (650) 723-0448.
  2. When working with liquid solutions containing MS-222, wear lab coat, safety glasses (or safety goggles + face shield if splash potential exists) and nitrile gloves.
  3. MS-222 stock solutions should be prepared by dissolving the powder in clean tank or system water. Since it is acidic, it must be buffered with sodium bicarbonate resulting in a solution of pH 7.0 - 7.5.
  4. MS-222 powder has a shelf life of up to 3 years, but can vary based on manufacturer. The stock powder should be stored in a manner that protects it from light (dark container) and maintained in a cool place.
  5. Once mixed, stock solution containers must be properly labeled as to content and dated to expire no longer than one month after preparation. Alternatively, stock solutions can be frozen and stored in an opaque, air-tight, light-safe container for storage up to 6 months. The stock solution should not be buffered (buffering should only happen for use, not storage). The solution must be replaced any time a brown color is observed in the liquid.
  6. Discard anesthetic solutions when fouled with mucus or metabolic waste. Anesthetic solutions can be maintained for several days without changing colors and efficiency at room temperature if maintained away from the light and maintained at cooler temperatures. However, the anesthetic solution should be at the appropriate temperature for the species when used for anesthesia or euthanasia.
  7.  Manage anesthetic solutions as hazardous waste or consult with EH&S’s Environmental Programs at (650) 725-7529 regarding alternative management.

If you have questions regarding this guideline please contact EH&S at (650) 723-0448.