Quantification Of Diclofenac Research Articles

Optimization of a Differential Pulse Voltammetric Methodology for the Quantification of Diclofenac Using Paste Electrodes and Carbon Nanotubes

In this work we present the development of an optimized methodology based on differential pulse voltammetry for diclofenac quantification, using electrochemically activated carbon paste electrodes and multi-walled nanotubes carbon paste electrodes. Under the optimized experimental conditions, diclofenac presented linear response over the range of 10-10 to 10-4 M for both electrodes. The lower detection limits found were 0.001 and 0.29 μM for the paste electrodes with and without nanotubes respectively. The effect of common interferences on diclofenac current response was investigated. Finally the proposed methodology was validated comparing the results obtained measuring the concentration of diclofenac in pharmaceutical samples with those obtained with the reference methodology.

Muscle Injury After Intramuscular Administration of Diclofenac: A Case Report Supported by Magnetic Resonance Imaging

Intramuscular injection of diclofenac is still frequently practiced, although there is ample evidence that the risk of local tissue intolerability is highly underestimated. The aim of this study was to evaluate local toxicity in a patient using magnetic resonance imaging. A patient who gave written informed consent received a medically indicated intramuscular administration of diclofenac 75 mg/2 mL. Simultaneously with magnetic resonance imaging of the depot, a clinical–chemical evaluation and quantification of diclofenac in plasma was performed. A manifold enhancement of the T2-weighted magnetic resonance signal was observed in a muscle area of approximately 60 mL volume, with maximum signal intensity 30 min after injection, the time of maximum diclofenac plasma exposure. Plasma creatine kinase activity was elevated approximately sixfold within 8 h and normalized within 1 week, whereas the magnetic resonance enhancement disappeared within 5 weeks. Interestingly, the patient did not complain about any clinical symptoms at the injection site. Asymptomatic tissue injury after intramuscular injection of diclofenac, caused by intramuscular dosing, can be reliably evaluated by magnetic resonance imaging and should be applied early during the development of parenteral dosage forms. Clinical Trials Registration Number: BB130/16 (Ethics Committee of the University Medicine Greifswald).

Mussels as bioindicators of diclofenac contamination in coastal environments

Diclofenac a nonsteroidal anti-inflammatory drug (NSAID) has been confirmed as an emerging contaminant in the aquatic environment. Toxicology studies have revealed that harmful effects may emerge from diclofenac presence not only for human health, but also for marine organisms, which implies its monitoring. To overcome the demanding challenges of diclofenac quantification in biotic aquatic species, a novel method for the determination of diclofenac in mussels (Mytilus galloprovincialis and Mytilus edulis) and macroalgae (Laminaria digitata) using high performance liquid chromatography coupled to tandem mass spectrometry was developed and validated according to the EC Decision 2002/657/EC. Additionally, a study was done about diclofenac contamination in mussels collected from 8 sites along the 1115 miles of coastline in Portugal in 2015. The results suggested that levels in mussels are closely related to the environmental contamination. Therefore, mussels can be a potential bioindicator of diclofenac contamination in the coastal environment.

Taking advantage of CTAB micelles for the simultaneous electrochemical quantification of diclofenac and acetaminophen in aqueous media

Cetyltrimethylammonium bromide hemimicelles, formed on the surfaces of a carbon paste electrode, selectively adsorbed diclofenac molecules from a neutral aqueous solution containing acetaminophen, allowing simultaneous quantification of both drugs.

Development and Validation by RP-HPLC Method for the Simultaneous Quantification of Diclofenac and Rabeprazole, in Capsule Formulation

Objective: Determination of Diclofenac and Rabeprazole in capsules formulations using reverse phase high pressure liquid chromatography method. Method/Statistical Analysis: Chromatographic separation was carried out on a Thermo hypersil-keystone C18 (250 x 4.6 mm, 0.5 μ) column in isocratic mode, using a mobile phase mixture comprising a 20:50:30 (% v/v/v) of Acetonitrile: methanol: phosphate buffer and UV detection at 257 nm. The percentage recoveries 100.11% and 110.04% respectively. The amount of Diclofenac and Rabeprazole found per capsule was 100.08 mg and 20.03 mg respectively. Findings: The proposed reverse phase high pressure liquid chromatography method shows good separation of Diclofenac sodium and Rabeprazole, were retention time was found to 5.3 (±0.5) min for Diclofenac sodium and 3.5 (±0.5) min for Rabeprazole, which show very less time consuming analysis. No previous method of analysis shows good separation at less retention time and less cost. Linearity range for Diclofenac and Rabeprazole were 25-125 μg/ml, 5-25 μg/ml. Application: The developed method can be successfully applied for estimation and determination of Diclofenac and Rabeprazole in bulk powder and combined capsule form.

Skin sample preparation by collagenase digestion for diclofenac quantification using LC-MS/MS after topical application.

Skin is the target site to evaluate the pharmacokinetic parameters of topical applications. Sample preparation is one of the influential steps in the bioanalysis of drugs in the skin. Evaluation of dermatopharmacokinetics at preclinical stage is challenging due to lack of proper sample preparation method. There is a need for an efficient sample preparation procedure for quantification of drugs in the skin using LC-MS/MS. The skin samples treated with collagenase followed by homogenization using a bead beater represents a best-fit method resulting in uniform homogenate for reproducible results. A new approach involving enzymatic treatment and mechanical homogenization techniques were evaluated for efficient sample preparation of skin samples in the bioanalysis.

Solid phase extraction and quantification of diclofenac sodium in human plasma by liquid chromatography-tandem mass spectrometry

A novel liquid chromatography-tandem mass spectrometry (LC-MS-MS) method is described for the quantitative determination of diclofenac in human K2EDTA plasma in negative ion mode and validated using zidovudine as internal standard (IS). Sample preparation was accomplished by solid phase extraction technique. The eluted samples were chromatographed on Zorbax XDB phenyl column (75 × 4.6 mm, 3.5 μm) Agilent Technologies, using a mobile phase consisting of HPLC grade acetonitrile—0.2% acetic acid in HPLC water (80: 20, v/v).The injection volume was 15 μL and the total run time was 2.0 min. The method was validated over a linear concentration range of 25 to 4004 ng/mL diclofenac. The precursors to product ion transitions m/z 294.10 to 249.90 (diclofenac) and m/z 266.0 to 222.90 (zidovudine, IS) were used for quantitation. The retention times were 1.12 and 0.86 min for diclofenac and zidovudine, respectively. Validation results show that the method is selective and capable of quantifying the analyte with good precision and accuracy. The method is stable for the studied parameters. Therefore, a rapid, sensitive LC-MS-MS method for quantification of diclofenac in human plasma was developed and can be used in therapeutic drug monitoring of this drug.

Diclofenac on Boron-Doped Diamond Electrode: From Electroanalytical Determination to Prediction of the Electrooxidation Mechanism with HPLC-ESI/HRMS and Computational Simulations

Using square-wave voltammetry coupled to the boron-doped diamond electrode (BDDE), it was possible to develop an analytical methodology for identification and quantification of diclofenac (DCL) in tablets and synthetic urine. The electroanalytical procedure was validated, with results being statistically equal to those obtained by chromatographic standard method, showing linear range of 4.94 × 10(-7) to 4.43 × 10(-6) mol L(-1), detection limit of 1.15 × 10(-7) mol L(-1), quantification limit of 3.85 × 10(-7) mol L(-1), repeatability of 3.05% (n = 10), and reproducibility of 1.27% (n = 5). The association of electrochemical techniques with UV-vis spectroscopy, computational simulations and HPLC-ESI/HRMS led us to conclude that the electrooxidation of DCL on the BDDE involved two electrons and two protons, where the products are colorful and easily hydrolyzable dimers. Density functional theory calculations allowed to evaluate the stability of dimers A, B, and C, suggesting dimer C was more stable than the other two proposed structures, ca. 4 kcal mol(-1). The comparison of the dimers stabilities with the stabilities of the molecular ions observed in the MS, the compounds that showed retention time (RT) of 15.53, 21.44, and 22.39 min were identified as the dimers B, C, and A, respectively. Corroborating the observed chromatographic profile, dimer B had a dipole moment almost twice higher than that of dimers A and C. As expected, dimer B has really shorter RT than dimers A and C. The majority dimer was the A (71%) and the C (19.8%) should be the minority dimer. However, the minority was the dimer B, which was formed in the proportion of 9.2%. This inversion between the formation proportion of dimer B and dimer C can be explained by preferential conformation of the intermediaries (cation-radicals) on the surface.

Optimization of diclofenac quantification from wastewater treatment plant sludge by ultrasonication assisted extraction

A rapid quantification method of diclofenac from sludge samples through ultrasonication assisted extraction and solid phase extraction (SPE) was developed and used for the quantification of diclofenac concentrations in sludge samples with liquid chromatography/tandem mass spectrometry (LC-MS/MS). Although the concentration of diclofenac in sludge samples taken from different units of wastewater treatment plants in Istanbul was below the limit of quantification (LOQ; 5ng/g), an optimized method for sludge samples along with the total mass balances in a wastewater treatment plant can be used to determine the phase with which diclofenac is mostly associated. Hence, the results will provide information on fate and transport of diclofenac, as well as on the necessity of alternative removal processes. In addition, since the optimization procedure is provided in detail, it is possible for other researchers to use this procedure as a starting point for the determination of other emerging pollutants in wastewater sludge samples.

Label-free optical biosensor for detection and quantification of the non-steroidal anti-inflammatory drug diclofenac in milk without any sample pretreatment

A label-free optical biosensor for detection and quantification of diclofenac in bovine milk has been developed. This was achieved by using reflectometric interference spectroscopy as detection method. In a first step, the immunosensor was developed and optimised in buffer concerning sensitivity, selectivity, stability and reproducibility. By comparing recovery rates—not only the good intra- but also the good inter-chip—reproducibility could be proven. Consequently, the assay was transferred in the more complex matrix milk. By utilising an optimised surface modification and evaluation method, matrix effects could successfully be prevented or circumvented. As a result, the developed immunosensor does not need sample pretreatment at all. By obtaining a limit of detection of 0.112 μg L(−1) (0.108 μg kg(−1)), the capability of the developed biosensor is comparable or better than those of standard detection methods. Moreover, the presented biosensor reaches the range of the maximum residue limit (0.1 μg kg(−1)) set by the European Union. Thus, for the first time, diclofenac was successfully quantified at relevant levels in milk by using an optical biosensor.

Erratum: Quantification of Diclofenac in Hospital Effluent and Identification of Metabolites and Degradation Products

In this study the occurrence of diclofenac and sub-products in effluent emerging from the University Hospital at the Federal University of Santa Maria was investigated. One metabolite was identified and, in aqueous solution, three degradation products. The quantification was conducted by means of HPLC-DAD, and the determination of metabolite and degradation products by LC–ESI–MS/MS–QTrap. For the HPLC-DAD method, a 70:30 mixture of methanol/sodium phosphate was used in isocratic mode. For the LC–ESI–MS/MS–QTrap determinations, a mobile phase, where phase A was an ammonium acetate solution 5 × 10−3 mol L−1, and phase B was methanol (5 × 10−3 mol L−1)/ammonium acetate (9:1, v/v), on gradient mode. The LDs for the HPLC and LC–MS/MS methods, respectively, were 2.5 and 0.02 µg L−1, the LQs, 8.3 and 0.05 µg L−1, and the linear range from 10 up to 2000 µg L−1 and 0.05 up to 10 µg L−1. As expected, the LC–ESI–MS/MS–QTrap method was more sensitive and less laborious. The metabolite 4′-hydroxy-diclofenac was identified. Photolysis was used for the degradation studies and three products of diclofenac were identified (m/z of 214, 286 and 303) in aqueous solution. These results notwithstanding, no degradation products of diclofenac were found in the hospital effluent.

Quantification of Diclofenac in Hospital Effluent and Identification of Metabolites and Degradation Products

AbstractIn this study the occurrence of diclofenac and sub‐products in effluent emerging from the University Hospital at the Federal University of Santa Maria was investigated. One metabolite was identified and, in aqueous solution, three degradation products. The quantification was conducted by means of HPLC‐DAD, and the determination of metabolite and degradation products by LC–ESI–MS/MS–QTrap. For the HPLC‐DAD method, a 70:30 mixture of methanol/sodium phosphate was used in isocratic mode. For the LC–ESI–MS/MS–QTrap determinations, a mobile phase, where phase A was an ammonium acetate solution 5 × 10−3 mol L−1, and phase B was methanol (5 × 10−3 mol L−1)/ammonium acetate (9:1, v/v), on gradient mode. The LDs for the HPLC and LC–MS/MS methods, respectively, were 2.5 and 0.02 µg L−1, the LQs, 8.3 and 0.05 µg L−1, and the linear range from 10 up to 2000 µg L−1 and 0.05 up to 10 µg L−1. As expected, the LC–ESI–MS/MS–QTrap method was more sensitive and less laborious. The metabolite 4′‐hydroxy‐diclofenac was identified. Photolysis was used for the degradation studies and three products of diclofenac were identified (m/z of 214, 286 and 303) in aqueous solution. These results notwithstanding, no degradation products of diclofenac were found in the hospital effluent.

Kinetic-Spectrophotometric Method for Diclofenac Quantification

–This paper introduces a kinetic-spectrophotometric method for diclofenac quantification and its application to pharmaceutical preparations. The redox reaction rate between diclofenac and KMnO4 in a strong acidic environment is determined. Plotting initial slope vs. concentration a good linearity has been found. Linear range of the essay was 5-20 ppm. The effect of temperature on the reaction rate has been studied and Ea was 21.48 kJ/mol. The proposed method was found to be highly precise, having a relative standard deviation, CV% = 1.3% for repeatability (n=10). Recovery of analyte in placebo 98.7 108.15%, values that fall within the requirements set by USP and ANMAT (National Drug, Food and Medical Technology Administration of Argentina). This spectrophotometric method was compared with HPLC. Statistical data show no significant difference between them. The proposed method was found to be simple, rapid, specific, allowing the determination without preliminary extraction procedures. Keywords––Diclofenac, kinetics, quantification, spectrophotometry, tablets.

HPLC Method for Determination of Diclofenac in Human Plasma and Its Application to a Pharmacokinetic Study in Turkey

A simple high-performance liquid chromatography (HPLC) method has been developed for determination of diclofenac in human plasma. The method was validated on Ace C(18) column using UV detection. The mobile phase consisted of 20 mM phosphate buffer (pH 7) containing 0.1% trifluoroacetic acid-acetonitrile (65:35, v/v). Calibration curve was linear between the concentration range of 75-4000 ng/mL. Intra- and inter-day precision values for diclofenac in plasma were less than 3.6, and accuracy (relative error) was better than 5.3%. The limits of detection and quantification of diclofenac were 25 and 75 ng/mL, respectively. Also, this assay was applied to determine the pharmacokinetic parameters of diclofenac in healthy Turkish volunteers who had been given 50 mg diclofenac.

Stir bar sorptive extraction of diclofenac from liquid formulations: A proof of concept study

A new stir bar sorptive extraction (SBSE) technique coupled with HPLC-UV method for quantification of diclofenac in pharmaceutical formulations has been developed and validated as a proof of concept study. Commercially available polydimethylsiloxane stir bars (Twister™) were used for method development and SBSE extraction (pH, phase ratio, stirring speed, temperature, ionic strength and time) and liquid desorption (solvents, desorption method, stirring time etc) procedures were optimised. The method was validated as per ICH guidelines and was successfully applied for the estimation of diclofenac from three liquid formulations viz. Voltarol® Optha single dose eye drops, Voltarol® Ophtha multidose eye drops and Voltarol® ampoules. The developed method was found to be linear (r=0.9999) over 100–2000ng/ml concentration range with acceptable accuracy and precision (tested over three QC concentrations). The SBSE extraction recovery of the diclofenac was found to be 70% and the LOD and LOQ of the validated method were found to be 16.06 and 48.68ng/ml, respectively. Furthermore, a forced degradation study of a diclofenac formulation leading to the formation of structurally similar cyclic impurity (indolinone) was carried out. The developed extraction method showed comparable results to that of the reference method, i.e. method was capable of selectively extracting the indolinone and diclofenac from the liquid matrix. Data on inter and intra stir bar accuracy and precision further confirmed robustness of the method, supporting the multiple re-use of the stir bars.

Determination of diclofenac on a dysprosium nanowire- modified carbon paste electrode accomplished in a flow injection system by advanced filtering.

A new detection technique called Fast Fourier Transform Square-Wave Voltammetry (FFT SWV) is based on measurements of electrode admittance as a function of potential. The response of the detector (microelectrode), which is generated by a redox processes, is fast, which makes the method suitable for most applications involving flowing electrolytes. The carbon paste electrode was modified by nanostructures to improve sensitivity. Synthesized dysprosium nanowires provide a more effective nanotube-like surface [1-4] so they are good candidates for use as a modifier for electrochemical reactions. The redox properties of diclofenac were used for its determination in human serum and urine samples. The support electrolyte that provided a more defined and intense peak current for diclofenac determination was a 0.05 mol L−1 acetate buffer pH = 4.0. The drug presented an irreversible oxidation peak at 850 mV vs. Ag/AgCl on a modified nanowire carbon paste electrode which produced high current and reduced the oxidation potential by about 100 mV. Furthermore, the signal-to-noise ratio was significantly increased by application of a discrete Fast Fourier Transform (FFT) method, background subtraction and two-dimensional integration of the electrode response over a selected potential range and time window. To obtain the much sensivity the effective parameters such as frequency, amplitude and pH was optimized. As a result, CDL of 2.0 × 10−9 M and an LOQ of 5.0 × 10−9 M were found for the determination for diclofenac. A good recovery was obtained for assay spiked urine samples and a good quantification of diclofenac was achieved in a commercial formulation.

Iron(II)-phthalocyanine as a novel recognition sensor for selective potentiometric determination of diclofenac and warfarin drugs

Construction and characterization of potentiometric membrane sensors for quantification of diclofenac and warfarin drugs are described. The membranes of the sensors incorporate 1.8 wt.% iron(II)-phthalocyanine (Pc) as a molecular recognition reagent, 64.3 wt.% dibutylsebacate (DBS) solvent mediator, 1.8 wt.% tridodecylmethylammonium chloride (TDMAC) as membrane additive and 32.1 wt.% poly(vinyl chloride) (PVC) as a matrix. The sensors display linear response for 1 × 10 −2 to 9 × 10 −6 mol l −1 (detection limit 5.4 × 10 −6 mol l −1) and 1 × 10 −2 to 5 × 10 −6 mol l −1 (detection limit 3 × 10 −6 mol l −1) with anionic slopes of −61 ± 1 and −63 ± 1 mV decade −1 over the pH range 5.5–9 for declofenac and warfarin, respectively. Validation of the assay methods according to the quality assurance standards confirms their suitability for quality control purposes. Use of the sensor for the assay of various formulations of the drugs shows a mean average recovery of 99.7% of the nominal values and a mean precision of ±0.3%. Significantly improved accuracy, precision, response time, stability, selectivity and sensitivity are offered by these simple and cost-effective potentiometric sensors compared with other standard techniques.

High-performance liquid chromatographic determination of diclofenac in human plasma after solid-phase extraction

A novel high-performance liquid chromatographic (HPLC) method for the quantification of diclofenac in human plasma was set up. Samples, added with ibuprofen (used as internal standard) were purified by solid-phase extraction using Abselut Nexus cartridges (Varian) not requiring pre-conditioning. Drugs of interest were eluted directly into the autosampler vials and injected. The recovery of diclofenac was 92%, the analysis lasted 7 min with a sensitivity of 5 ng/ml and intra- and inter-day RSDs of 3 and 8%, respectively. The pharmacokinetics of diclofenac after oral and rectal administration in 10 healthy volunteers are reported.

Spectrofluorimetric determination of diclofenac in the presence of α-cyclodextrin

This study focuses on the complex formed between α-cyclodextrin (CD) and the anti-inflammatory drug diclofenac in aqueous solution and also on its potential analytical applications. It was corroborated that the fluorescence emission band of diclofenac is significantly intensified in the presence of α-CD. From the changes in the fluorescence spectra, it was concluded that α-CD forms a 1:1 inclusional complex with diclofenac and its equilibrium constant was calculated to be 1.20(3)×10 3 M −1. With the purpose of characterizing the inclusion complex, the acid–base behaviour of diclofenac in both the presence and absence of α-CD was spectrophotometrically investigated. From the results obtained, it was inferred that both the carboxyl and the secondary amino groups of the guest molecule remain outside the cyclodextrin cavity. Further details on the complex structure was obtained by 1H NMR measurements and semiempirical calculations. In addition to the analysis of the α-CD–diclofenac interaction, a new approach for the quantification of diclofenac in the presence of α-CD is described in the range 0–5 μg ml −1. An application of the method to the determination of the studied drug in pharmaceutical preparations is shown.

Complexation study of diclofenac with beta-cyclodextrin and spectrofluorimetric determination.

The inclusional complexation between the anti-inflammatory pharmaceutical diclofenac and beta-cyclodextrin (beta-CD) was studied by potentiometry, spectrophotometry and spectrofluorimetry, in both acid and neutral pH. Guest-host 1:1 stoichiometries for the complexes in both media were determined, and their equilibrium constants were calculated. The values obtained from the different methods used are in very good agreement and are in the order of 10(3). From the analysis of the pKa value for diclofenac in both the absence and presence of beta-CD (4.84 and 4.90 respectively), it was inferred that in the inclusion complex the carboxylic group is located outside the cavity. Further structural characterization of the inclusate was carried out by means of 1H NMR spectra and AM1 semiempirical calculations. Based on the obtained results, a spectrofluorimetric method for the determination of diclofenac in the presence of beta-CD was developed in the range of 0-5 micrograms ml-1. Better limits of detection (0.03 microgram ml-1) and quantification (0.1 microgram ml-1) were obtained in this latter case with respect to those obtained in the absence of beta-CD. The method was satisfactorily applied to the quantification of diclofenac in pharmaceutical preparations.