REAGENTS

  1. 8-Amino-1-naphthol-3, 6-disolfonic acid, monosodium salt.
  2. Salicylaldehyde - Do not allow to come in contact with skin.
  3. 10% KOH: weigh 10g KOH into 100 mL volumetric flask and dilute to volume with deionized water.
  4. 1:4 HC1: Add 25 mL of conc. HCl to 75 mL of deionized water.
  5. Ascorbic Acid

PREPARATION

  1. Weigh 18 g of 8-Amino-1-naphthol-3, 6-disolfonic acid, monosodium salt into 2 liter beaker.
  2. Add 1100 mL. Deionized water and heat with stirring until dissolved.
  3. Adjust pH to 7.0 with 10% KOH.
  4. Adjust pH to 1.5 with 1:4 HCl solution.
  5. Put back on hot plate and stir until dissolved.
  6. Add 21 mL salicylaldehyde.
  7. Heat and stir for 1 hour.
  8. Let stand overnight.
  9. Filter under vacuum using Whatman #1 paper and a Buchner funnel.
  10. Rinse beaker with methyl alcohol and pour into the funnel.
  11. Put azomethine-H cake into a 250 mL beaker.
  12. Add 100 mL deionized water and 5 g ascorbic acid.
  13. Mix up the slurry and transfer into 500 mL volumetric flask.
  14. Add 350 mL deionized water and heat on a water bath until dissolved.
  15. Filter hot solution through Whatman #1 paper into 600 mL beaker.
  16. Cover and store in refrigerator overnight.
  17. Proceed as in steps 9 and 10.
  18. Rinse filtrate with five 10 mL portions of methyl alcohol.
  19. Remove azomethine-H cake from funnel and dry for 2 hours at 85 °C and store in a desiccator.