GLC determination of l-2-hydroxy-N-cyclopropylmethylmorphinan in plasma and urine

A specific method was developed for the determination of l-2-hydroxy-N-cyclopropylmethylmorphinan in plasma and urine by GLC, using flame-ionization detection. The method involves the extraction of the compound into ether from plasma or urine at pH 7.4, followed by back-extraction into 1 N HCl. The acid phase is ether washed and made alkaline, and the compound is reextracted into ether. The ether is evaporated to dryness, the residue is dissolved in methanol, and an aliquot is analyzed by GLC. The same method is applicalble to plasma and urine samples following deconjugation of the compound with glucuronidase-sulfatase. The overall recovery is 93.1 +/- 9.4% SD) in the concentration range of 0.020-2.0 microgram/ml. The method was successfully applied to plasma and urine specimens obtained after administering single 25-mg oral doses to humans.