Determination of codeine and morphine in Brown Mixture (opium preparations) in Taiwan using SPE and GC/MS

Brown Mixture (BM), containing opium powder (10.0-10.5% morphine), opium tincture (0.9-1.1% morphine), or camphorated opium tincture (0.045-0.055% morphine), is a popular remedy, while heroin use is prohibited in Taiwan. Thus, for specimens that are tested positive for morphine, specimen donors' claims of BM use have to be adequately addressed. This study was designed to develop and validate a gas chromatography-mass spectrometry (GC-MS) method for simultaneous quantitation of codeine and morphine in BM in order to gain further insights related to the ingestion of BM. The effectivenesses of solidphase extraction (SPE) cartridges and deuterated analogs (d3and d6-) of codeine and morphine in the sample preparation and quantitative determination processes were evaluated. Conclusions were reached that codeine and morphine can be effectively analyzed, qualitatively and quantitatively, as trimethylsilyl derivatives, using selective ion monitoring of the following ions: m/ z 371, 372, 343 for codeine and 377, 378, 349 for codeine-d6; 429, 414, 401 for morphine and 435, 420, 404 for morphine-d6. The overall protocol achieved the following results when applied to the analysis of 1 mL opiates-free BM specimens fortified with 50–1500 ng/mL codeine and morphine: recovery, 90.00–100.87%; interday and intraday precision ranges, 1.10–6.46% and 1.04–3.91%, respectively; linearity, r2 > 0.997; limits of detections, 30 ng/mL for codeine and 20 ng/mL for morphine; limits of quantitation, 30 ng/mL for codeine and 40 ng/mL for morphine. Eight BM products (5 tablets and 3 solutions) from 7 different manufacturers were analyzed for their morphine and codeine contents. The contents of morphine and codeine in the tablets were found very consistent, with the morphine-to-codeine concentration ratios ranging from 8.66 to 9.09 (mean = 8.85, standard deviation = 0.16), but were found to vary considerably in the 3 BM solutions (morphine-to-codeine concentration ratios: 2.19, 2.34, 3.28).