Simultaneous determination of 6-monoacetylmorphine, morphine and codeine in urine using high-performance liquid chromatography with combined ultraviolet and electrochemical detection

Electrochemical Determination of Morphine in Urine Samples by Tailoring FeWO4/CPE Sensor

Morphine (MORPH) is natural alkaloid and mainly used as a pain reliever. Its monitoring in human body fluids is crucial for modern medicine. In this paper, we have developed an electrochemical sensor for submicromolar detection of MORPH. The sensor is based on modified carbon paste electrode (CPE) by investigating the Fe_xW_1-xO₄ ratio in iron tungstate (FeWO₄), as well as the ratio of this material in CPE. For the first time, the effect of the iron-tungsten ratio in terms of achieving the best possible electrochemical characteristics for the detection of an important molecule for humans was examined. Morphological and electrochemical characteristics of materials were studied. The best results were obtained using Fe₁W₃ and 7.5% of modifier in CPE. For MORPH detection, square wave voltammetry (SWV) was optimized. Under the optimized conditions, Fe₁W₃@CPE resulted in limit of detection (LOD) of the method of 0.58 µM and limit of quantification (LOQ) of 1.94 µM. The linear operating range between 5 and 85 µM of MORPH in the Britton-Robinson buffer solution (BRBS) at pH 8 as supporting electrolyte was obtained. The Fe₁W₃@CPE sensor resulted in good selectivity and excellent repeatability with relative standard deviation (RSD) and was applied in real-world samples of human urine. Application for direct MORPH detection, without tedious sample pretreatment procedures, suggests that developed electrochemical sensor has appeared to be a suitable competitor for efficient, precise, and accurate monitoring of the MORPH in biological fluids.

A Review of Analytical Methods for Codeine Determination

Codeine is derived from morphine, an opioid analgesic, and has weaker analgesic and sedative effects than the parent molecule. This weak opioid is commonly used in combination with other drugs for over-the-counter cough relief medication. Due to the psychoactive properties of opioid drugs, the easily obtained codeine often becomes subject to misuse. Codeine misuse has emerged as a concerning public health issue due to its associated adverse effects such as headache, nausea, vomiting, and hemorrhage. Thus, it is very important to develop reliable analytical techniques to detect codeine for both quality control of pharmaceutical formulations and identifying drug misuse in the community. This review aims to provide critical outlooks on analytical methods applicable to the determination of codeine.

Fully automated analytical method for codeine quantification in human plasma using on-line solid-phase extraction and high-performance liquid chromatography with ultraviolet detection

A simple, sensitive and fully automated analytical method for the analysis of codeine in human plasma is presented. Samples are added with oxycodone, used as internal standard (I.S.), and directly loaded in the autosampler tray. An on-line sample clean-up system based on solid-phase extraction (SPE) cartridges (Bond-Elut C2, 20 mg) and value switching (Prospekt) is used. Isocratic elution improved reproducibility and allowed the recirculation of the mobile phase. A Hypersil BDS C18, 3 microns, 10 x 0.46 cm column was used and detection was done by UV monitoring at 212 nm. Retention times of norcodeine (codeine metabolite), codeine and oxycodone (I.S.) were 5.5, 6.4 and 9.1 min, respectively. Morphine was left to elute in the chromatographic front. Detection limit for codeine was 0.5 microgram l-1 and inter-assay precision (expressed as relative standard deviation) and accuracy (expressed as relative error) measured at 2 micrograms l-1 were 5.03% and 1.82%. Calibration range was 2-140 micrograms l-1.

Involvement of codeine in drug-related deaths

The incidence and role of codeine in drug-related deaths in Victoria was investigated over a 5-year period. There were a total of 107 cases involving codeine, representing 8.8% of all drug-related deaths in this period in Victoria. There were only six fatalities in which codeine was considered the major poison. The mean (+/- SD) concentration of codeine in femoral blood was 4.0 +/- 2.3 mg/L (range, 2.1-8.0 mg/L). The mean concentration of free codeine was 1.3 +/- 0.9 mg/L (range, 0.4-2.8 mg/L). The remaining 101 cases involved a combination of codeine and other drugs. The mean total codeine blood concentration was 1.8 +/- 3.3 mg/L (range, 0.04-26 mg/L), which was significantly lower than in those cases where codeine was the major poison (p < 0.002). The mean concentration of free codeine was 0.82 +/- 4.9 mg/L (range, 0.02-9.0 mg/L), which was not significantly different (p > 0.05) from the six codeine-only cases. The most common drugs found in this group, other than codeine, were acetaminophen (62%), diazepam (46%), salicylate (20%), and ethanol (25%). The association of other psychoactive drugs in these deaths made the contribution of codeine difficult to assess. Free codeine concentrations > 0.4 mg/L and total codeine concentrations > 2.0 mg/L may be sufficient to cause death in the absence of any other contributing factors.

Solid phase extraction of morphine and its metabolites from postmortem blood

A simple and rapid high-performance liquid chromatographic method is described for the determination of morphine-3-glucuronide, morphine-6-glucuronide, normorphine and morphine in postmortem blood. A solid phase extraction technique employing C18 Sep-Pak cartridges was used to recover morphine and its metabolites from 0.5 ml of blood. Reverse phase ion-pair chromatography was used to achieve separation with a C18 bonded column. The mobile phase consisted of acetonitrile, lauryl sulphate and sodium dihydrogen orthophosphate buffer at low pH. Electrochemical detection (ECD) in series with ultraviolet (UV) spectrophotometric detection (210 nm) was used for quantitation. The lower limit of detection using ECD was 10 ng/ml for all analytes and a linear response was observed to 5000 ng/ml. Coefficients of variation for all analytes ranged between 3-13% for both intra- and inter-assay. This method is reproducible, quick and easy to perform and allows morphine conjugates and morphine to be measured simultaneously in postmortem blood.

Reversed-phase high-performance liquid chromatography--photodiode-array analysis of alkaloid drugs of forensic interest

A reversed-phase high-performance liquid chromatography-photodiode-array method for the analysis of 23 drugs of forensic interest is presented. The separation method development was based on mobile-phase optimisation, temperature control and use of three ODS stationary phases. Multiwavelength detection and quantitation was performed at 225, 232, 239, 254, 275 and 289 nm. Absorbance rationing proved to be very helpful for the identification of these drugs. Recognition of the analysed compounds was achieved by means of correlation of retention time and absorbance ratios. The method was directly applied to the analysis of illicit heroin and cocaine samples and to the analysis of pharmaceutical preparations containing codeine.