• In addition to dilute commercial bleach (sodium hypochlorite), calcium hypochlorite and PPM (Plant Preservative Mixture) as disinfecting agents, other chemicals are available.
• This "new" chemical, sodium dichloroisocyanurate, as known as NaDCC, can be used as a disinfesting agent AND a media constituent to help eliminate contamination.
• NaDCC is often used as a pool disinfectant and can often be purchased at discount stores such as K-Mart, Shopko, Wal-Mart and Home Depot.
• It is also sold under the name of "Trichloroisocyanuric acid" or "Trichlor-s-triazinetrione" or "Trichlor".
• NaDCC solutions appear to be more stable than other chlorine based compounds. The solutions used for disinfecting plant pieces are stable for at least 48 hours. This will vary depending on the type of container used for storage and the storage temperatures. See reference paper below for more information.

How to use it as a disinfecting agent?

• NaDCC is messy and smelly. Read the MSDS before handling.
• Wear a dust mask, gloves, and goggles.
  
• Do not work near food.  THIS SHOULD NOT BE PREPARED IN THE KITCHEN.
  
• If soaking plants for 10-30 minutes, it has been recommended to use a solution of 1/8 + 1/4 teaspoon NaDCC added to 1 cup of water (about 250 ml).  This is rather strong and needs to be tested with the individual plant that your are working with.  I recommend starting with a lower concentration (maybe 1/4 teaspoon)
  
• If soaking plants overnight, add 1/8 teaspoon NaDCC to 5 cups of water. Mix well. Stir occasionally to insure that the solution is getting in contact with all parts of the plant piece.  USE CAUTION HERE TOO:  The length of time will have to be determined experimentally. Some plants tolerate a long soaking time in a dilute solution and others will tolerate a stronger concentration for a shorter period of time. Test a piece first and look for signs of browning or bleaching, OR  try different lengths of time.
  
• After soaking in the NaDCC solution, you can transfer plant pieces to sterile water. Soak in sterile water for at least 5 minutes, or transfer to fresh sterile water after a few minutes. OR You can culture the plant pieces directly on the medium without rinsing.
  
• Check the MSDS for proper disposal methods for your area.

How to use it as a media constituent to limit contamination?

Add 1/8 teaspoon NaDCC to 750 ml water (about 3 cups). Mix well Add 20 ml of this solution to your plant tissue culture medium and process as usual.

Example: To make African violet medium:

______ 2 cups water
______ 1 packet MS basal medium
______ 1 mg BAP
______ 20 ml NaDCC solution

Mix well. Add more water to bring volume to 1 quart. Adjust pH with vinegar or baking soda. Dispense into baby food jars. Add agar or cotton balls. Microwave per manual instructions. All plants will not be able to tolerate the high chlorine concentration in the medium. Experimenting with your particular species will be necessary.

References

Email message to the Home Tissue Culture List in February 1999 from Dr. Emerson Del Ponte (delponte@ufpel.tche.br).   See archive.

Parkinson, M., M. Prendergast, and AJ Sayegh. 1996. Sterilization of explants and cultures with sodium dichloroisocyanurate. Plant Growth Regulation 20: 61-66.