PubMed · 3856766
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I R Edwards. 1985-03-27. Dextropropoxyphene.. https://pubmed.ncbi.nlm.nih.gov/3856766/
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The use of blood spot collection cards is a simple way to obtain specimens for analysis of drugs with a narrow therapeutic window. We describe the development and validation of a microanalytical technique for the determination of paracetamol and its glucuronide and sulphate metabolites from blood spots. The method is based on reversed phase high-performance liquid chromatography with ultraviolet detection. The limit of detection of the method is 600 pg on column for paracetamol. Intra- and inter-day precision of the determination of paracetamol was 7.1 and 3.2% respectively. The small volume of blood required (20 microl), combined with the simplicity of the analytical technique makes this a useful procedure for monitoring paracetamol concentrations. The method was applied to the analysis of blood spots taken from neonates being treated with paracetamol.
A method based on capillary electrophoresis with electrochemical detection (CE-ED) was developed for the simultaneous determination of p-aminophenol and acetaminophen in the hydrolysates of acetaminophen. Effects of several important factors such as the acidity and concentration of running buffer, separation voltage, injection time, and working potential were investigated to acquire the optimum conditions. The detection electrode was a 300 microm carbon disc electrode at a working potential of +0.80 V (versus SCE). The two analytes can be well separated within 6 min in a 50 cm length fused silica capillary at a separation voltage of 18 kV in a 25 mM phosphate buffer (pH 6.5). The rate constants of acetaminophen hydrolysis in 0.5 M HCl at different temperatures were determined by monitoring the concentration changes of acetaminophen. At 70, 80, 90 and 100 degrees C, the measured rate constants of acetaminophen hydrolysis were 5.027 x 10(-3), 8.522 x 10(-3), 18.60 x 10(-3) and 32.76 x 10(-3) min(-1), respectively. The activation energy for acetaminophen hydrolysis was calculated to be 68.13 kJ mol(-1), which is in good agreement with the value in the literature.
Acetaminophen, phenylephrine and chlorpheniramine are frequently associated in pharmaceutical formulations against the common cold. Their quantification presents several problems. A HPLC method for the simultaneous determination of these compounds in pharmaceutical formulations such as capsules and sachets, including the separation of impurities and excipients has been developed and validated. The selectivity of the method was also tested to be used if phenylpropanolamine hydrochloride were employed instead of phenylephrine. Final chromatographic conditions were a gradient elution, being solvent A: phosphate buffer 40 mM at pH 6.0 and solvent B: acetonitrile. At t=0, the mobile phase consisted of 92% A and 8% B and it changed with a linear gradient during 8 min to 75% A and 25% B. At min 8, it changed to 30% A and 70% B for 5 min and at t=15 min, it returns to the initial conditions (92% A and 8% B) during 1 min remaining at this composition until t=20 min. UV detection was performed at 215 nm for phenylephrine and chlorpheniramine, because at this wavelength sensitivity was higher than in other more characteristic wavelengths and it was necessary for the detection of minor compounds. For acetaminophen 280 nm was employed. Validation parameters permit to consider the method adequate.