Acidification of compost with 0.5 N HCl

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  1. Using the large plastic carboy marked “0.5 N HCl” add 6 liters of deionized water to the carboy.
  2. Work in the fume hood and wear acid gloves and goggles. Gloves are in the cabinet marked “Corrosives” next to the acid. Using a beaker or graduated cylinder measure out 260 mL of concentrated HCl and add slowly to the carboy containing water. Always make sure to add the acid to the water. Rinse the beaker with water a couple times and pour that waste into the acid solution. Mix by shaking gently. The 0.5 N solution then does not need to be kept in the fume hood.
  3. To do the acidifications, weight out 100 g of compost material into a rubbermaid dish. Label the dish with the proper sample ID and date that was on the original sample bag. Add 200 mL of 0.5 N HCl to the dish. Using a spoon, break up the compost and spread it out along the bottom of the dish so the acid covers the material. Set in the fume hood to dry for several days (6 full days is usually good).
  4. When the material is dry use the spoon or spatula to break up the dry material. Transfer to a labeled ziploc bag, using the same labels as previously. When an entire set of samples has been acidified and dried, store those bags together in a large bag, label that bag and take it to the grinding room. Record the new samples on the list on the wall in the grinding room.
  5. Also record the dates the samples were acidified and dried on the data sheet in the lab.