Abstract
In this work a simple flow injection methodology with pulsed amperometric detection for simultaneous determination of dipyrone (DI) and paracetamol (PCT) in pharmaceutical formulations is described. The compounds are detected by applying four sequential potential pulses as function of the time. Dipyrone is directly detected at +0.40 V and paracetamol indirectly at 0.00 V through the reduction of the oxidation product (N-acetyl-p-benzoquinoneimine) electrochemically generated at +0.65 V. The fourth potential pulse (-0.05 V) is applied for the cleaning of the electrode surface (glassy carbon). The linear response range was optimized between 9 and 45 mg L-1 for dipyrone and 6 and 30 mg L-1 for paracetamol. Linear regression of these two series of experiments leads to excellent correlation coefficients (R = 0.999) for both analytes and recoveries of around 100%. The proposed methodology allows an analytical frequency of 45 injections h-1 with a consumption of 1.5 mL of solution per minute. The relative standard deviation for 24 successive injections of solutions containing DI and PCT was calculated as 0.4% and 0.2%, respectively. The developed methodology was successfully used for the determination of dipyrone and paracetamol in pharmaceutical samples.
Highlights
Dipyrone (DI), known as metamizol, is a widely used analgesic and antipyretic with proven efficiency in pharmaceutical formulations.[1]
We present for the first time a methodology for simultaneous determination of DI and PCT in pharmaceutical formulations using Flow injection analysis (FIA) with Multiple pulse amperometric detection (MPA) detection
Results of the simultaneous determination of DI and PCT in commercial samples were compared with the ones obtained by the Pharmacopoeia method, such as the determination of dipyrone,[7] and sometimes using previously published methods, such as the determination of paracetamol by titration with Ce4+ solution.[22]
Summary
Dipyrone (DI), known as metamizol, is a widely used analgesic and antipyretic with proven efficiency in pharmaceutical formulations.[1]. Electroanalytical techniques are considered an alternative for the development of methods with reduced time and analysis costs, because they frequently enable the direct determination of electroactive compounds in complex samples.[26] Among the electroanalytical methods, amperometric detection at constant potential coupled with FIA system provides good selectivity and high frequency for the analytical determination of many compounds.[27,28] this method of detection is limited for cases in which the simultaneous determination of electroactive compounds at the same working electrode is required.
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