Sensitive spectrophotometric method for determining methadone in biological specimens

✍ Scribed by Jack E. Wallace; Horace E. Hamilto; James T. Payte; Kenneth Blum

• Publisher: John Wiley and Sons
• Year: 1972
• Tongue: English
• Weight: 425 KB
• Volume: 61
• Category: Article
• ISSN: 0022-3549
• DOI: 10.1002/jps.2600610911

✦ Synopsis

The extensive use of methadone for the treatment of opiate addiction increases significantly the need for quantitative determination of methadone in urine and tissues. Existing spectrophotometric methods are limited in sensitivity by the low molar absorptivity of this compound (E = 554 in 0.1 N HCl, X = 292 nm.). Results demonstrate that a markedly enhanced sensitivity may be achieved by oxidizing the methadone to benzophenone (E = 18,713 in n-heptane, h = 247 nm.). Methadone is extracted into ri-hexane at an alkaline pH and then back-extracted into dilute sulfuric acid. Refluxing the acid solution with barium peroxide and n-heptane oxidizes the methadone to benzophenone, which is immediately extracted into the heptane. The heptane layer is removed and washed, and the benzophenone is measured spectrophotometrically. The method is sufficiently sensitive to quantitate therapeutic levels of methadone in small volumes of urine.