Determination of Small Amounts of Morphine in Blood

Abstract

The fate of morphine in the animal body is a question that has stimulated much excellent work and the development of many methods for the determination of the drug. We do not have space to enumerate, much less to discuss, these methods, 2 of the more recent examples of which are those described by Wolff, Riegel, and Fry 1 and by Abe and Uchida. 2 Most of these methods were unsuited to our purpose since they were not designed for use with blood, and the others required more material or a more elaborate procedure than we wished to employ.

The method herein described has the advantage of simplicity, takes but a few hours to complete, and gives quantitative results with small amounts of blood. It is based on that of Sanchez, 3 which was designed for the determination of morphine in pure solution. We have modified it for use with blood filtrates, deproteinized by the method of Somogyi, 4 introducing scopolamine to bring down the precipitate and permit the removal of the reacting solutions. The method in detail is as follows: A 1-to-10 filtrate is prepared by laking 1 part of blood with 7 parts of water. To this is added with constant stirring 1 part 10% zinc sulphate and 1 part 0.5 N sodium hydroxide.∗ After standing 10 minutes the precipitate is centrifuged down and the supernatant liquid filtered through No. 2 Whatman paper. Treated in this manner 5 cc. blood yield over 30 cc. filtrate.

To 20 cc. of the filtrate, equivalent to 2 cc. blood, is added 2.5 mg. of scopolamine hydrobromide, from a solution containing 1 mg. per 1 cc. (Proportionally smaller amounts may be used if the concentration of morphine is high.) The morphine is then precipitated by 0.4 cc. of Wavelet's solution.† The material is thoroughly mixed by stirring or shaking, and set in a cold place for about an hour.