Gas-liquid chromatographic quantitation of cocaine.HCl in pouders and tablets: collaborative study.

Eight laboratories collaboratively studied a method for the quantitative gas-liquid chromatographic (GLC) determination of cocaine.HCl in solid forms. The cocaine.HCl and other water solubles are dissolved in dilute HCl. The aqueous solution is made weakly basic with K2HPO4, and the organic solubles are extracted into CHCl3 for the GLC determination of cocaine. Tetracosane (n-C24) is incorporated in the extracting CHCl3 as an internal standard. Five samples of known cocaine.HCl concentration and one sample of commercial ground tablets were collaboratively studied. The cocaine.HCl content ranged from 6 to 100%. Recoveries ranged from 98.7 to 103%; coefficients of variation ranged from 0.89 to 3.16. The method was adopted as official first action.