An automated method for the determination of diclofenac sodium in human plasma

An automated method utilizing laboratory robotics has been developed for quantifying diclofenac sodium concentrations in human plasma. The robotic system aliquots the biological sample, adds the internal standard (CGP 4287), extracts the compounds from the acidified biological matrix (pH less than 2) into an organic phase (hexane-isopropyl alcohol), and concentrates the extracts for reversed-phase, high-performance liquid chromatographic (HPLC) analysis. The laboratory robot is directly interfaced to the HPLC system, and the data are automatically collected and results calculated. Separation is achieved on a 3-microns ODS (6.2-mm x 8.0-cm) column with ultraviolet (UV) detection of the drug and internal standard at 280 nm. Recovery and reproducibility assessments indicate good accuracy (overall mean relative recovery of 99.8%) and precision (coefficient of variation from 0.5 to 11.1%) over the diclofenac sodium concentration range of 5.0-1000 ng/mL, with a quantification limit of 5.0 ng/mL. The method has been successfully applied to a pharmacokinetic study in which normal volunteers received 150 mg of a prototype controlled-release formulation of diclofenac sodium.     

Development and validation of stability-indicating HPLC method for the simultaneous determination of paracetamol, tizanidine, and diclofenac in pharmaceuticals and human serum

A method is described for the simultaneous determination of paracetamol, tizanidine, and diclofenac in mixtures. The method was based on HPLC separation of the three drugs followed by UV detection at 254 nm. The separation was carried out on a Hypersil ODS, C18 (250 x 4.6 mm id, 10 microm particle size) column using the mobile phase aqueous 0.2% ammonium carbonate-methanol (60 + 40, v/v) at a flow rate of 1 mL/min. The linear regression analysis data were used for the regression curve in the range of 170-10 000 ng/mL for paracetamol, 120-10 000 ng/mL for tizanidine, and 20-10 000 ng/mL for diclofenac. No chromatographic interference from tablet excipients was found. In order to check the selectivity of the proposed method, degradation studies were carried out using hydrolysis (acid, basic, and neutral), thermolysis, and oxidation. The developed method, after being validated in terms of precision, robustness, recovery, LOD, and LOQ, was successively applied to the analysis of pharmaceutical formulations and human serum.     

Extraction and Spectrophotometric Determination of Diclofenac in Pharmaceuticals

A new simple, rapid and sensitive spectrophotometric method has been developed for the determination of diclofenac sodium (Dicl) in pharmaceutical preparations. This method is based on the reaction of diclofenac sodium with an analytical reagent 1,3,3‐trimethyl‐5‐thiocyanato‐2‐[3‐(1′,3′,3′‐trimethyl‐3′‐H‐indol‐2′‐ylidene)‐propenyl]‐indolium cloride (TIC) at pH 8.0‐11.0 and the extraction of ion associate colored complex. Optimal conditions for the complex formation between Dicl and TIC were studied. This ion associate complex (1:1) was detected and extracted with toluene and an absorption maximum at 566.2 nm against a blank reagent. The calibration graph was linear from 0.9‐11.0 μg/mL of diclofenac and the detection limit was 0.86 μg/mL.     

Determination of diclofenac in plasma by high-performance liquid chromatography with electrochemical detection

A reversed-phase high-performance liquid chromatographic method with electrochemical detection for the quantitative determination of diclofenac potassium in plasma was developed. Naproxen was used as the internal standard. The drug and internal standard were isolated from plasma by extraction with dichloromethane and 2 M hydrochloric acid. Chromatographic separation was performed on a C18 column with methanol-water (68:32, v/v) adjusted to pH 3.2 with phosphoric acid as mobile phase. The oxidation potential for detection was established by constructing a voltammogram for diclofenac. The quantification limit for diclofenac in plasma was 5 ng mL(-1). Linearity of the method was confirmed in the range 5-2000 ng mL(-1), correlation coefficient 0.9998. Within-day relative standard deviations (RSDs) ranged from 0.66 to 14.00% and between-day RSDs from 0.59 to 15.78%. The method was successfully applied for the determination of pharmacokinetic parameters after ingestion of a 50 mg dose of diclofenac. Studies were performed on 18 healthy volunteers of both sexes.     

Simultaneous determination of aceclofenac and three of its metabolites in human plasma by high-performance liquid chromatography

Aceclofenac [[2-(2',6'-dichlorophenyl)amino]phenylacetoxyacetic acid] is a phenylacetic acid derivative with potent analgesic and anti-inflammatory properties and an improved gastro-intestinal tolerance. In the present study, a liquid-liquid extraction-based reversed-phase HPLC method with UV detection was validated and applied for the analysis of aceclofenac and three of its metabolites (4'-hydroxy-aceclofenac, diclofenac, 4'-hydroxy-diclofenac) in human plasma. The analytes were separated using an acetonitrile-phosphate buffer gradient at a flow rate of 1 mL/min, and UV detection at 282 nm. The retention times for aceclofenac, diclofenac, 4'-hydroxy-aceclofenac, 4'-hydroxy-diclofenac and ketoprofen (internal standard) were 69.1, 60.9, 46.9, 28.4 and 21.2 min, respectively. The validated quantitation range of the method was 10-10000 ng/mL for aceclofenac, 4'-hydroxy-aceclofenac and diclofenac, and 25-10000 ng/mL for 4'-hydroxy-diclofenac. The developed procedure was applied to assess the pharmacokinetics of aceclofenac and its metabolites following administration of a single 100 mg oral dose of aceclofenac to three healthy male volunteers.     

Determination of diclofenac sodium in commercial pharmaceutical formulations and human control serum using a kinetic-spectrophotometric method

A kinetic method for the determination of micro quantities of diclofenac sodium (DS) is described in this paper. The method is based on a ligand-exchange reaction. The reaction was followed spectrophotometrically by monitoring the rate of appearance of the cobalt diclofenac complex at 376 nm. The optimum operating conditions regarding reagent concentrations and temperature were established. The optimized conditions yielded a theoretical detection limit of 1.29 microg ml(-1) based on the 3S(b) criterion. The interference effects of certain drugs, foreign ions and amino acids upon the reaction rate were studied in order to assess the selectivity of the method. The developed procedure was successfully applied to the rapid determination of diclofenac sodium in commercial pharmaceutical preparations and human control serum. The unique features of this procedure are that determination can be carried out at room temperature and the analysis time is short. The newly developed method is simple, inexpensive, and efficient for use in the analysis of a large number of samples.     

Simultaneous determination of diclofenac potassium and drotaverine hydrochloride in human plasma using reversed-phase high-performance liquid chromatography

A simple high-performance liquid chromatographic method with ultraviolet detection is proposed for the estimation of diclofenac potassium and drotaverine hydrochloride in human plasma. Liquid-liquid extraction was carried out with a mixture of dichloromethane-isopropyl alcohol (80:20, v/v). Chromatographic separation of the analytes and internal standard was achieved on an analytical 250 × 4.6 mm i.d. reversed-phase Thermo BDS Hypersil C8 (5 μm particle size) column using a mobile phase of acetonitrile-0.02M ammonium acetate buffer (53:47, v/v) at pH 3.5. The run time was less than 15 min. Column eluate was monitored at 230 nm. The linearity over the concentration ranges of 25-1500 ng/mL and 32-960 ng/mL was obtained for diclofenac potassium and drotaverine hydrochloride, respectively. The limit of quantification was 25 and 32 ng/mL for diclofenac potassium and drotaverine hydrochloride, respectively. Recoveries of diclofenac potassium and drotaverine hydrochloride from plasma were 97.45% and 98.27%, respectively.     

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.     

Determination of ceftriaxone sodium in pharmaceutical formulations by flow injection analysis with acid potassium permanganate chemiluminescence detection.

Based on the chemiluminescence (CL) emission generated from the oxidation of ceftriaxone sodium alkali hydrolysate by potassium permanganate in polyphosphoric acid (PPA), a novel determination method for ceftriaxone sodium was developed by using a flow-injection technique. The calibration curve appears to be linear in the range between 0.05 and 100 microg mL(-1) with a detection limit (3sigma) of 25 ng mL(-1), and a relative standard deviation (RSD) of 0.6% for eleven replicate determinations of 5.0 microg mL(-1) ceftriaxone sodium. The proposed method has been successfully utilized for the determination of ceftriaxone sodium in pharmaceutical formulations, while the chemiluminescence reaction mechanisms were investigated.     

Simultaneous determination of disopyramide and mono-N-dealkyldisopyramide enantiomers in human plasma by capillary electrophoresis

In this paper, a rapid method for the enantioselective analysis of the antiarrhythmic drug disopyramide and its main metabolite mono-N-dealkyldisopyramide in human plasma by capillary electrophoresis employing the cyclodextrin-modified electrokinetic chromatography mode is described. Sample clean-up was carried out by alkalinization with sodium hydroxide followed by liquid-liquid extraction with toluene. The complete enantioselective analysis was performed within less than 5 min using 20 mmol/L sodium acetate buffer, pH 5.0, containing 0.2% w/v sulfated beta-cyclodextrin as chiral selector. A 40 cm uncoated fused-silica capillary was used for the analysis, performed at a voltage of 15 kV and at 20 degrees C. The calibration curves were linear over the concentration range of 62.5-1850 ng/mL and 125-1850 ng/mL for each enantiomer of disopyramide and mono-N-dealkyldisopyramide. The mean recoveries for disopyramide and mono-N-dealkyldisopyramide enantiomers were up to 87 and 69%, respectively. All four enantiomers studied could be quantified at three different concentrations (200, 400 and 600 ng/mL) with coefficient of variation and % relative error not higher than 15%. The quantitation limit was 62.5 ng/mL for (+)-(S)-and (-)-(R)-disopyramide and (-)-(R)-mono-N-dealkyldisopyramide and 125 ng/mL for (+)-(S)-mono-N-dealkyldisopyramide, using 1 mL of human plasma.     

Flow-injection chemiluminescence determination of penicillin antibiotics in drugs and human urine using luminol-Ag(III) complex system

A chemiluminescent (CL) system based on the reaction of an Ag(III) complex with luminol in alkaline medium is presented. Gamma order of magnitude penicillin species antibiotics could dramatically enhance CL intensities. Coupled with flow injection analysis (FIA), a novel sensitive chemiluminescent analytical technique for some penicillin antibiotics in drugs and urine samples is introduced. Under optimum conditions, benzylpenicillin sodium, amoxicillin, ampicillin and cloxacillin sodium were determinated. Detection limits of this method are 70 ng/mL for benzylpenicillin sodium, 67 ng/mL for amoxicillin, 169 ng/mL for ampicillin and 64 ng/mL for cloxacillin sodium. For the spiked urine samples, the recoveries of the four drugs were in the range of 106–112% for benzylpenicillin sodium, 104–110% for amoxicillin, 104–106% for ampicillin, and 103–105% for cloxacillin sodium. Based on the fluorescence spectra, free radical trapping experiment, and chemiluminescent spectra, a possible reaction mechanism is suggested.     

Enantiomeric determination of praziquantel and its main metabolite trans-4-hydroxypraziquantel in human plasma by cyclodextrin-modified micellar electrokinetic chromatography

A capillary electrophoresis method for the simultaneous quantitation of praziquantel and its main metabolite trans-4-hydroxypraziquantel enantiomers in human plasma was developed and validated using cyclodextrin-modified micellar electrokinetic chromatography. Sample clean-up involved a single-step liquid-liquid extraction of plasma with toluene after the addition of NaCl. The complete enantioselective analysis was obtained in less than 7 min using 2% w/v sulfated beta-cyclodextrin as chiral selector and 20 mmol/L sodium deoxycholate as surfactant, in 20 mmol/L sodium borate buffer, pH 10. A 50 microm x 42 cm uncoated fused-silica capillary was used for the analysis, performed at a voltage of 18 kV and at 20 degrees C. The calibration curves were linear over the 125-625 ng/mL concentration range. The mean recoveries for praziquantel and trans-4-hydroxypraziquantel were up to 96 and 71%, respectively, with good precision. All four enantiomers were quantified at two concentration levels (200 and 600 ng/mL) with precision and accuracy below 15%. The quantitation limit was 50 ng/mL for (-)-(R)- and (+)-(S)-praziquantel and 62.5 ng/mL for (-)-(R)- and (+)-(S)-trans-4-hydroxypraziquantel, using 1 mL of human plasma.     

Non-protected fluid room-temperature phosphorimetric procedure for the direct determination of naftopidil in biological fluids

Non-protected fluid room temperature phosphorescence, NPRTP, has been applied to the determination of naftopidil in biological fluids. The proposed method is based on obtaining a phosphorescence signal from naftopidil using potassium iodide as heavy atom perturber and sodium sulfite as a deoxygenating reagent without a protected medium. Optimized conditions for the determination were 1.4 mol L= KI, 5.0 x l0(-3) mol L(-1) sodium sulfite, pH 6.5 (adjusted with sodium hydrogen phosphate-dihydrogen phosphate buffer solution, 5.0 x 10(-2) mol L(-1). The delay time, gate time, and time between flashes were 70 micros, 400 micros, and 5 ms, respectively. The maximum phosphorescence signal appeared instantly and the intensity was measured at lambda(ex)=287 nm and lambda(em)=525 nm. The response obtained was linearly dependent on concentration in the range 50 to 600 ng mL(-1). The detection limit, according to error-propagation theory, was 7.93 ng mL(-1) and the detection limit as proposed by Clayton was 11.12 ng mL(-1). The repeatability was studied by using ten solutions of 400 ng mL(-1) naftopidil; if the theory of error propagation is assumed the relative error is 0.88%. The standard deviation of replicates was found to be 3.5 ng mL(-1). This method was successfully applied to the analysis of naftopidil in human serum and urine with recoveries of 104.0 +/- 0.6% for serum and 106.0 +/- 1.0% for urine.     

Simultaneous Quantitation of Captopril and NSAID's in API,Dosage Formulations and Human Serum by RP‐HPLC

An accurate, sensitive and least time consuming reverse phase high performance liquid chromatographic (RP‐HPLC) method for the estimation of captopril in the presence of non steroidal anti‐inflammatory drugs in formulation and human serum has been developed and validated. Chromatographic separation was conducted on prepacked Purospher star C18 (5 μm, 25 × 0.46 cm) column at room temperature using methanol:water (80:20 v/v) as a mobile phase, pH adjusted at 2.8 with o‐phosphoric acid and at a flow rate of 1.0 mL min⁻¹, while UV detection was performed at 227 nm. The limit of detection and quantification for captopril were 1 and 0.35 ng mL⁻¹, while that for (NSAID's) i.e. flurbiprofen, ibuprofen, diclofenac sodium and mefenamic acid LOD were 0.2, 1, 2 and 0.4 ng mL⁻¹ respectively and LOQ were 0.9, 2.9, 8 and 1 ng mL⁻¹ Analytical recovery was > 98.1%. The method used for the quantitative analysis of commonly administered non steroidal anti‐inflammatory drugs (NSAID's) i.e. ibuprofen, flurbiprofen, diclofenac sodium and mefenamic acid alone or in combination with captopril from API (active pharmaceutical ingredients), dosage formulations and in human serum. The established method is rapid (RT < 12 min), accurate (recovery > 98.1%), selective (no interference of excepients and other commonly used drugs and food) and sensitive (LOQ 3.5 ng mL^;‐1) and reproducible (SD ± 0.003).     

Photokinetic voltammetric method for the determination of thiocyanate

Thiocyanate traces have a strong inhibitory effect on the oxidation of Neutral Red by potassium bromate under UV irradiation in diluted phosphoric acid. Neutral Red exhibits a sensitive second derivative oscillopolarographic wave at -0.6 V(vs. SCE) in diluted phosphoric acid and sodium acetate solution. The oscillopolarographic behavior of Neutral Red was selected as indicator component for its photo-activated oxidation. The photochemical reaction rate equation was determined. A detection limit of 0.3 ng mL(-1) (3sigma/k) and a linear calibration curve from 2.0-48.0 ng mL(-1) thiocyanate were obtained. The method was applied to the determination of thiocyanate in urine, saliva and serum with satisfactory results.     

Catalytic determination of ultra trace amounts of tellurium by 2.5-order differential oscillopolarography

A highly sensitive and selective catalytic method with 2.5-order differential oscillopolarographic detection is described for the determination of tellurium, based on its activation effect on the slow Pd(II)-catalyzed reaction of sodium hypophosphite and methyl red in hydrochloric acid medium at 100 degrees C. Methyl red exhibited a sensitive 2.5-order differential polarographic wave at -0.35 V (vs. SCE) in the supporting electrolyte of pH 5.0 acetate buffer solution and was chosen as the indicating component for the indirect determination of tellurium. A calibration curve of tellurium in the range of 0.02-2.0 ng mL(-1) was obtained by the fixed-time procedure. The detection limit was 0.007 ng mL(-1). Possible interferences by co-existing substances were examined. The new method has been used to analyze trace tellurium in organs of white mice with satisfactory results. RSD was 0.54% to 2.10%, recovery 98.4% to 95.7%. The mechanism is also discussed.     

Determination of sodium tanshinone IIA sulfonate in plasma by liquid chromatography-electrospray ionisation-tandem mass spectrometry

Sodium tanshinone IIA sulfonate (STS) is a water-soluble derivative of tanshinone IIa, an important lipophilic component contained in Salvia miltiorrhizae. A simple, sensitive and robust quantification method for STS based on LC-ESI-MS/MS was developed and validated, and has been successfully applied to the pharmacokinetic study. Liquid-liquid extraction was used for extracting STS from biological samples, with a satisfactory recovery exceeding 75% at all test concentrations. Isocratic mobile phase consisted of 75% acetonitrile and 25% water containing 0.005% ammonia acetate (pH 3). Good retention and baseline separation for STS and the selected internal standard, diclofenac sodium, were obtained on a Shim-pack VP-ODS analytical column under this condition. The method was linear in the concentration range of 1-500 ng/mL. The intra- and inter-day precisions (RSD%) were within 9.0%. The deviation of the assay accuracies was within +/-10.0%. STS was proved to be stable during all sample storing, preparation and analytic procedures. With a lower limit of quantitation at 1 ng/mL, this method has been proved to be sensitive enough for the pharmacokinetic study of STS. The plasma profile of STS followed a single intravenous dosing was well fitted to a three compartmental model.     

增效试剂在动力学分析法中的应用研究Ⅱ: 锰(Ⅱ)-氨三乙酸-十二烷基硫酸钠-高碘酸钾-罗丹明B催化体系

基于存在活化剂氨三乙酸和增敏剂十二烷基硫酸钠, 锰(Ⅱ)催化高碘酸钾氧化罗丹明B的反应, 拟定了测定痕量锰的新催化光度法。讨论了有关的反应机理。本法由于添加了表面活性剂, 灵敏度提高3.4倍。测定锰含量线性范围为10-120ng·25mL^-^1, 相对标准偏差为2.6%(n=9), 检出限为8.0×10^-^1^1g·mL^-^1。用于测定水样和酒样中锰。     

Determination of Tributyltin in Sea Water by Hydride Generation-Atomic Absorption Spectrometry

A hydride generation-atomic absorption spectrometry (HG-AAS) procedure is described for the analysis of tributyltin (TBT) in sea water. TBT is first converted to its volatile hydride form by reaction with sodium borohydride, followed by cryogenic trapping at ?196°C, and finally detection by atomic absorption spectrometry using an electrically heated quartz atomization cell. The linear range of calibration is 5-250 ng TBT (as tin). At the 5-ng level, the relative standard deviation (RSD) is 13%. The absolute detection limit (3σ) is 1.8 ng. Based on a sample volume of 500 mL, this value corresponds to a concentration detection limit 3.6 ng L^?1 TBT This method has been successfully applied to the analysis of TBT in sea water collected from Keelung and Kaohsiung harbors.     

Reagent injection FIA system for lead determination by hydride generation - quartz-tube atomic absorption spectrometry

A method is proposed for the determination of lead by generation of its hydride and detection by quartz-tube AAS using a reagent injection FIA system based on the injection of sodium tetrahydroborate. Lead hydride generation was carried out using a combination of 0.5 M nitric acid, 10% m/ v hydrogen peroxide and 10% m/ v sodium tetrahydroborate. The characteristic concentration obtained was 3.1 ng mL(-1) and the detection limit was 2.6 ng mL(-1) for an injected volume of 0.125 mL of tetrahydroborate.