PubMed · 11488191
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P E Haavik. 2001-06-20. [Information on preparations containing codeine].. https://pubmed.ncbi.nlm.nih.gov/11488191/
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The amperometric detection of codeine and its metabolite, morphine following capillary zone electrophoretic separation is described. A carbon-disk electrode used as working electrode for two analytes exhibited a good response at 0.90 V (vs. Ag/AgCl). The optimal conditions of separation and detection were pH 8.4 phosphate buffer solution (0.06 mol x l(-1)), 12 kV for the separation voltage, sample injection at 12 kV for 10 s. The linear ranges were from 3.1 x 10(-7) to 2.5 x 10(-5) mol x l(-1) for codeine and 1.9 x 10(-7) to 1.5 x 10(-5) x mol l(-1) for morphine with a correlation coefficient of 0.9996 and 0.9999, respectively. The detection limits for codeine and morphine were 1.6 x 10(-7) and 6.8 x 10(-8) x mol l(-1). The method developed was successfully applied to the determination of codeine and its metabolite, morphine in the human urine without any other sample pretreatment except filtration, and the results were satisfactory.
Two simple and sensitive kinetic methods for the determination of tramadol hydrochloride are described. The first method is based upon a kinetic investigation of the oxidation reaction of the drug with alkaline potassium permanganate at room temperature for a fixed time at 20 min. The absorbance of the colored manganate ions was measured at 610 nm. The second method is based on the reaction of tramadol hydrochloride with 4-chloro-7-nitrobenzofurazan (NBD-Cl) in presence of 0.1 M sodium bicarbonate. The spectrophotometric measurements were recorded by measuring the absorbance at 467 nm, at fixed time at 25 min on thermostated water bath at 90+/-1 degrees C. All variables affecting the development of the colour have been investigated and the conditions were optimised. The absorbance concentration plots in both methods were rectilinear over the range 5-25 and 50-250 microg ml(-1), for the first and second methods, respectively. The two methods have been applied successfully to commercial capsule and ampoule dosage form. The results obtained are compared statistically with those given by the reference spectrophotometric method. The determination of tramadol hydrochloride by the fixed concentration and rate constant methods is feasible with the calibration equations obtained, but the fixed time method proves to be more applicable.
A validated method for the determination of remifentanil in human blood, applicable to all therapeutic concentrations, using capillary GC with nitrogen-specific detection and fentanyl as the internal standard has been developed. Citrated whole blood samples were extracted into 1-chlorobutane following precipitation of proteins with methanol. The drugs were back extracted into 10 mM HCl and re-extracted into methanol-1-chlorobutane. The extracts were reconstituted in methanol and injected onto a 25-m BPX-5 column. The lower limit of quantitation was 0.2 ng/ml with within- and between-day coefficients of variation of less than 15%.