Electron-capture gas-liquid chromatography was used to study the spontaneous hydrolysis of heroin in phosphate buffer (pH 6.4 and pH 7.4) at 23 degrees C. Aliquots of solution were taken over a 24-h period. After extraction at pH 8.9 into propan-2-ol (10%)-ethyl acetate, deacetylated products were made into hepafluorobutyrate derivatives which were analyzed quantitatively using nalorphine as the internal standard.
Heroin decomposes to 06-monoacetylmorphine (06-MAM) under these conditions. Further decomposition to morphine was not observed. Spontaneous hydrolysis was faster at pH 7.4 (first-order rate constant, 9.6 x 10-5 min-1) than at pH 6.4 (first-order rate constant, 3.0 x 10-5 min-1).
In 24 h, the decomposition to 06-MAM was 13 and 4%, respectively.(
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