Acid-Base Indicator Properties of Synthesized Phenylhydrazones: 4-(2-(2,4-Dinitrophenyl) Hydrazono) Methyl)-2 Methoxy Phenol and 4-(2-(2,4-Dinitrophenylhydrazono) Methyl) Benzene-1,3-diol

Table 2

Colour changes and pH ranges were observed during titrimetric analysis.

Indicator	NaOH vs. HCl		NaOH vs. CH3COOH		Assay of ibuprofen
	Colour	pH range	Colour	pH range	Colour	pH range
Methyl red	Yellow to red	4.40–6.20	Yellow to red		—	—
Methyl orange	Yellow to orange	3.00–4.4	Yellow to orange		—	—
Phenolphthalein	Pink to colourless	8–10	Pink to colourless		Pink to colourless
IND-X	Yellow to pink	8.02–10.20	Pink to colourless	8.02–10.20	Pink to colourless	8.02–10.20
IND-Y	Yellow to deep pink	8.00–10.20	Pink to colourless	8.00–10.20	Pink to colourless	8.00–10.20

—: not applicable.