Abstract
Conditions for the organic solvent extraction of the blue color (indothymol) formed by the reaction of thymol and ammonia nitrogen were investigated, and a following procedure was established.
Less than 30 ml of a solution containing 0.45 μg, of ammonia nitrogen was brought to pH about 10. After an addition of 2.5 ml of carbonate buffer (pH 10) solution containing 0.03% of sodium hypochlorite, within 2 min. 4 ml of thymol solution (prepared before use by mixing its 10% acetone solution with equal volume of 0.7 N sodium hydroxide solution) was added and pH was adjusted to 11.411.9. After about 2 hours, the solution was transferred to a polyethylene separatory funnel and diluted to about 50 ml with water. After an addition of 5 ml of sodium hydroxide solution (4N) and 18 g of sodium chloride, 10 ml of iso-butanol was added and extracted by shaking for 1 min. The organic. layer was separated and the absorbance at 675 mμ was measured.
