Determination Of Dipyrone Research Articles

Spectrophotometric Assay of Dipyrone in Pharmaceutical Preparations Via Oxidative Coupling Reaction with

A simple, rapid and highly sensitive spectrophotometric method has been described for the determination of dipyrone in a bulk and in dosage forms. The method depends on the organic oxidative coupling reaction of dipyrone with m-toluidine in the presence of potassium hexacyanoferrate (III) in aqueous solution to form purple product measured at 530 nm. Beer’s law is obeyed in the concentration range 0.4-10.0 g.ml-1 with accuracy (average recovery) of 99.71% and precision (RSD) is less than 2%. The molar absorptivity is 40770 l.mol-1.cm-1 with LOD 0.051 g.ml-1 and LOQ 0.167 g.ml-1. The analytical results agree favourably with official method (iodimetric method) and also with certified values.

Simultaneous Determination of Dipyrone and Papaverine in Pharmaceutical Formulation using PLS Regression and UV Spectrophotometry

A combination of sodium dipyrone and papaverine hydrochloride is used as an analgesic and antispasmodic drug. A simple and rapid procedure is proposed for simultaneous determination of these drugs in commercial formulations (Melpaz®) based on partial least squares (PLS) regression and UV spectrophotometric measurements in the range of 218–300 nm. The calibration set was built with 25 solutions in concentrations ranging from 15.0–35.0 mg ml−1 for dipyrone and from 0.5–1.5 mg ml−1 for papaverine in methanol. The relative standard deviation (RSD) was 1.05% for dipyrone and 1.55% for papaverine in pharmaceutical formulations. The percent of relative recovery was 95.9% for dipyrone and 95.2% for papaverine. Figures of merit, such as accuracy, precision, sensitivity and adjust were also determined. The methodology was validated by using an independent method, based on high performance liquid chromatography (HPLC).

A simplified reflectometric method for the rapid determination of dipyrone in pharmaceutical formulations

This paper describes a simple, portable and environmentally friendly method for the rapid determination of dipyrone in pharmaceuticals by using diffuse reflectance spectroscopy. The proposed method is based on the reflectance measurements of the orange compound produced from the spot test reaction between dipyrone and p-dimethylaminocinnamaldehyde (p-DAC), in acid medium, using a filter paper as solid support. Experimental design methodologies were used to optimize the measurement conditions. All reflectance measurements were carried out at 510 nm and the linear range was from 1.42 <FONT FACE=Symbol>´</FONT> 10-4-2.85 <FONT FACE=Symbol>´</FONT> 10-3 mol L-1, with a correlation coefficient of 0.999. The limit of detection (LOD) and the limit of quantification (LOQ) were 1.20 <FONT FACE=Symbol>´</FONT> 10-5 mol L-1 and 4.00 <FONT FACE=Symbol>´</FONT> 10-5 mol L-1, respectively. The intraday precision and interday precision were studied for 10 replicate analyses of 7.90 <FONT FACE=Symbol>´</FONT> 10-4 mol L-1 dipyrone solution. The coefficients of variation were 1.1 and 0.9%, respectively. The proposed method was applied successfully to the determination of dipyrone in commercial brands of pharmaceuticals. No interferences were observed from the common excipients in formulations. The results obtained by the proposed method were favorably compared with those given by the Brazilian Pharmacopoeia procedure at 95% confidence level.

Flow‐Injection Spectrophotometric Determination of Dipyrone in Pharmaceutical Formulations Using Ammonium Molybdate as Chromogenic Reagent

A simple and rapid flow‐injection spectrophotometric method is reported for the determination of dipyrone in pharmaceutical formulations. The method is based on the reaction of dipyrone with ammonium molybdate in acidic medium to produce blue molybdenum, which was detected spectrophotometrically at 620 nm. The analyte was determined in a single‐line flow system. The calibration curve obtained was linear in the range of 5×10−4 to 8×10−3 mol L–1 for dipyrone concentration and the precision (s r=1.7%) was satisfactory. The method proved to be selective and adequately sensitive. Application of the method to the analysis of pharmaceutical samples resulted in excellent accuracy; the percent mean recoveries were in the range 95.3%–101% and relative errors less than 5.0% for five pharmaceutical formulations were found.

Simultaneous Determination of Residues of Dipyrone and Its Major Metabolites in Milk, Bovine Muscle, and Porcine Muscle by Liquid Chromatography/Mass Spectrometry

A new liquid chromatography/mass spectrometry (LC/MS) method for the determination of dipyrone (DIP) and the DIP-related residues 4-formylaminoantipyrine (FAA), 4-aminoantipyrine (AA), and 4-methylaminoantipyrine (MAA) in milk, bovine muscle, and porcine muscle is presented. The analytes are extracted from the sample with methanol and defatted with hexane. The methanol extracts are then concentrated and injected into the LC system. Compounds are determined by reversed-phase LC using an Inertsil ODS-3 column with ammonium formate-acetonitrile mobile phase and MS detection using positive-ion electrospray ionization. Calibration curves were linear between 0.02 and 0.20 microg/g matrix equivalent concentration for FAA, AA, and MAA, and between 0.2 and 2.0 microg/g for DIP. The relative standard deviations for measurements by the proposed method were <11% for milk and porcine samples, with slightly greater variability for bovine samples. Average recoveries ranged from 82 to 128%, depending on the compound and matrix involved. The method detection limits of FAA, AA, and MAA were <0.02 microg/g for all matrixes tested, while those of DIP were <0.13 microg/g. The proposed method is rapid, simple, and specific, allowing a single analyst to easily prepare over 20 samples in a regular working day.

Rapid, simple and accurate liquid chromatography–diode array detection validated method for the determination of dipyrone in solid and liquid dosage forms

The goal of this study was to develop and validate a liquid chromatography (LC) method for the rapid determination of dipyrone (metamizole sodium) in solid and liquid formulations. Samples were extracted with water and filtered prior to LC analysis. The analytical procedure involved reversed phase LC with a Zorbax SB C 18 column (5 μm particle size, 4.6 mm × 250 mm i.d.), isoctratic methanol/water (80/20, v/v) mobile phase with UV detection at 254 nm. The flow rate was 1 mL min −1 , injection volume was 100 μL and retention time of dipyrone was 3.3 min. The method was validated with respect to linearity, precision and accuracy. Calibration curves were linear in the range 0.5–100 μg mL −1 for analyte and the recoveries at three levels (10, 15 and 25 μg mL −1 ) ranged from 93 to 100%. All results for dipyrone were confirmed by liquid chromatography–mass spectrometry (LC–MS) and 1 H nuclear magnetic resonance (NMR) spectroscopy. Due to its simplicity and accuracy, the assay method is suitable for routine analysis of both solid and liquid formulations and seven retail samples were analyzed using the validated method.

A flow injection method for biamperometric determination of dipyrone in pharmaceuticals

A flow-injection method for determination of dipyrone (novalgin, metamizol) in pharmaceutical tablets with biamperometric detection is described. Flow-parameters such as flow rate, coil length and sample injection volume were optimized. The calibration graph was linear ( r=0.9997) within the range of 10–50 mg l −1 in a 1-mmol l −1 HCl carrier solution for an applied potential of 100 mV between the two platinum wire electrodes. Two indicating redox systems were studied, namely Fe(III)/Fe(II) and I 2/I − . The former proved to be well suited as a selective and sensitive biamperometric indicating system for dipyrone in the presence of ingredients commonly accompanying the drug. The developed method was successfully applied to the determination of dipyrone in several commercial pharmaceutical preparations. The sampling rate was 71 samples per hour with a rsd of 1.6% (eight injections of a 14-mg l −1 dipyrone solution). Recoveries close to 100% demonstrated the reliability of the proposed method.

A flow injection method for biamperometric determination of dipyrone in pharmaceuticals

A flow-injection method for determination of dipyrone (novalgin, metamizol) in pharmaceutical tablets with biamperometric detection is described. Flow-parameters such as flow rate, coil length and sample injection volume were optimized. The calibration graph was linear ( r =0.9997) within the range of 10–50 mg l −1 in a 1-mmol l −1 HCl carrier solution for an applied potential of 100 mV between the two platinum wire electrodes. Two indicating redox systems were studied, namely Fe(III)/Fe(II) and I 2 /I − . The former proved to be well suited as a selective and sensitive biamperometric indicating system for dipyrone in the presence of ingredients commonly accompanying the drug. The developed method was successfully applied to the determination of dipyrone in several commercial pharmaceutical preparations. The sampling rate was 71 samples per hour with a rsd of 1.6% (eight injections of a 14-mg l −1 dipyrone solution). Recoveries close to 100% demonstrated the reliability of the proposed method.

Flow injection amperometric determination of dipyrone in pharmaceutical formulations using a carbon paste electrode

The behavior of a carbon paste electrode was investigated as an amperometric detector for the determination of dipyrone by flow injection analysis (FIA). The electrode presented low cost and easy construction by simple mixing of graphite powder and mineral oil. Initially, an electrochemical study of the dipyrone oxidation at a carbon paste electrode has been developed before its use in the FIA system. The oxidation currents monitored at +0.35 V versus Ag/AgCl, were proportional to the dipyrone concentrations. Experimental parameters, such as nature of supporting electrolyte, pH of the carrier solution, flow rate, sample volume injection and probable interferents were investigated. Under the best experimental conditions selected, the calibration curve for dipyrone was linear in the concentration range from 4.91×10 −6 to 2.50×10 −4 mol l −1 ( I anodic/μA)=0.056+81.06 [dipyrone]) with a detection limit of 2.07×10 −6 mol l −1. Recoveries ranged from 93.8 to 100.8% and an analytical frequency of 130 h −1 was achieved. The proposed flow procedure has been satisfactorily applied to the determination of dipyrone in several pharmaceutical formulations.

Diffusion layer titration of dipyrone in pharmaceuticals at a dual-band electrochemical cell

This paper describes the use of a thin-layered dual-band electrochemical cell operating at flow conditions to determine dipyrone (sodium salt of 1-phenil-2,3-dimethyl-4-methylaminomethanesulfonate-5-pyrazolone) by reaction with electrogenerated iodine. The electrolytic cell consisted of two closely spaced gold electrodes, the upper stream electrode serving as the generator electrode and the downstream electrode working as the collector electrode. A linear dynamic range from 2 to 15 μmol l −1 dipyrone was obtained by using a sample volume of 100 μl, with a detection limit of 1.1 μmol l −1. Standard deviation (S.D.) of 3.4% for 20 repetitive injections of a 40 μmol l −1 dipyrone solution and sampling frequency of 90 h −1 were achieved. The results obtained with the thin-layered dual-band electrochemical cell for dipyrone determination in three different pharmaceutical samples compared well with those found by iodimetry with coulometrically generated iodine.

Multi-pumping flow system for the spectrophotometric determination of dipyrone in pharmaceutical preparations

A novel flow system for the spectrophotometric determination of dipyrone with p-dimethylaminobenzaldehyde exploiting the multi-pumping approach was developed. The proposed methodology utilises several micro-pumps for propelling the involved fluids under improved mixing conditions, introducing sample/reagent aliquots and providing commuting facilities. As a consequence the multi-pumping system presents high versatility and manifold simplicity, as well as a straightforward operational control and enhanced analytical capabilities. Linearity of the analytical curve was observed within 10 and 400 mg l −1 dipyrone ( r=0.9997; n=6), results were precise (r.s.d.<0.12%; n=20) and sampling rate was 50 h −1. Detection limit was estimated as 1 mg l −1 dipyrone. The method was applied to pharmaceutical preparations and the results were in agreement with those obtained by the reference procedure with relative deviations within −1.7 and +2.2%.

Determination of dipyrone in pharmaceutical products by flow injection analysis with potentiometric detection.

This work describes an FIA potentiometric procedure for the quantification of dipyrone in pharmaceutical products. For the detector, a tubular electrode comprising a polymeric membrane containing tetraoctylammonium as an electroactive material (5% w/w), dibutylphtalate as a mediator solvent (65% w/w) and PVC (30% w/w) directly applied above a graphite conductor support was used. This unit was incorporated into a monochannel FI-system with a 0.1 mol/L phosphate buffer solution (pH = 5.2) as the carrier solution. The electrode showed a linear response from 8.0 x 10(-4) to 10(-1) mol/L dipyrone, a slope of 62.1 +/- 0.2 mV/dec in pH 5.2 units, an injection volume of 500 microL and a carrier flow-rate of 6 mL/min. This procedure was applied to the analysis of pharmaceutical formulations (oral and injectable) containing dipyrone; the obtained results gave a relative error of less than 3.9% and coefficients of variation less than 1% and 5%, respectively, for the FIA and classical iodometric methods.

Amperometric determination of dipyrone in pharmaceutical formulations with a flow cell containing gold electrodes from recordable compact discs

Amperometric determination of dipyrone in pharmaceutical formulations with a flow cell containing gold electrodes from recordable compact discs

Amperometric determination of dipyrone in pharmaceutical formulations with a flow cell containing gold electrodes from recordable compact discs

A simple, rapid, and precise amperometric method for quantification of dipyrone in pharmaceutical formulations is presented. The proposed method permits determinations in the 10−7 mol L−1 of the analyte and enables 90 determinations h−1, employing only 100 μL of sample per determination. This method is based on the direct quantification of dipyrone in many pharmaceutical products, avoiding cumbersome processes such as previous separations, solvent extraction, or sample filtration. This new procedure was applied to commercial pharmaceutical tablets, and the results obtained were in excellent agreement with the ones obtained by the classical iodometric method. © 2001 Wiley‐Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1972–1977, 2001

Spectrophotometric determination of dipyrone in pharmaceutical preparations by using chromotropic acid

A spectrophotometric method for the determination of dipyrone in pharmaceutical preparations is proposed. This method is based on selective oxidation of dipyrone, in the presence of sulphuric acid, splitting off formaldehyde which reacts with chromotropic acid, also in a sulphuric acid medium, producing a violet–red compound ( λ max 575 nm). Beer’s law is obeyed in a concentration range of 0.57–5.7 ppm dipyrone with an excellent correlation coefficient ( r=0.9997). The results show a simple, accurate, selective and readily applied method to the determination of dipyrone in pharmaceutical products. The analytical results obtained for these products by the proposed method are in agreement with those of the Brazilian Pharmacopoeia procedure. No interference was observed from common excipients in formulations. Recoveries were within 98.7–101.2%, with standard deviations ranging from 0.2 to 1.7%.

Titrimetric determination of dipyrone and paracetamol with potassium hexacyanoferrate(III) in an acidic medium.

A method is described for the determination of dipyrone and paracetamol in pharmaceutical preparations in which aliquots containing 1–15 mg of the sample are allowed to react with a known excess of potassium hexacyanoferrate(III) in 10 ml of 8 M sulphuric acid and 5 ml of 3% zinc sulphate solution at 35 °C in a thermostatically controlled water-bath for 15 min (paracetamol) or 25 min (dipyrone). The excess of potassium hexacyanoferrate(III) is then determined iodimetrically. The analysis of a mixture containing dipyrone and paracetamol in pharmaceutical preparations is carried out after their separation, which is based on the difference in their solubilities. On treatment with distilled water, dipyrone goes into solution while paracetamol remains insoluble and is subsequently dissolved in hydrochloric acid by heating on a boiling water-bath for 30 min. Results are within a ± 1.0% error.

Stability indicating assay for dipyrone. Part II. Separation and quantitative determination of dipyrone and its degradation products by high-performance liquid chromatography

A rapid, sensitive and reproducible procedure for separation and quantification of dipyrone and three of the degradation products is proposed, using high-performance liquid chromatography on a reversed-phase column and ultraviolet detection. The method is about ten times more sensitive (detection limit 3–5 ng) than thin-layer chromatography and requires only a 12-min elution time. This method has been applied to the analysis of tablets and injections.

Stability indicating assay for dipyrone. Part I. Separation and quantitative determination of dipyrone and its degradation products by thin-layer chromatography

A thin-layer chromatographic procedure is described for the separation and quantification of dipyrone in situ in the presence of three of the major degradation products. The repeatability and detection limits are given and the applicability of the assay in checking the stability of tablets and injections is shown.

Application of difference spectrophotometry to the determination of dipyrone.

Application of difference spectrophotometry to the determination of dipyrone.

Spectrophotometric determination of dipyrone with neotetrazolium chloride.

Spectrophotometric determination of dipyrone with neotetrazolium chloride.