M Cresol or metacresol is a precursor to synthetically man made pesticides. M Cresol is also found in synthetic vitamin E.
The Ka for metacresol purple is not readily available. The pH range for this indicator is typically around 7.2 to 9.8 where the color transition occurs. At pH 9.0, metacresol purple would likely be predominantly purple, indicating a higher pH level.
Active ingredient: insulin lispro. Inactive ingredients: glycerin, dibasic sodium phosphate, metacresol, zinc oxide (zinc ion), trace amounts of phenol and water for injection. skissime@yahoo.com