Capillary electrophoresis with laser-induced fluorescence: a routine method to determine moxifloxacin in human body fluids in very small sample volumes

Eco-friendly approach for determination of moxifloxacin in pharmaceutical preparations and biological fluids through fluorescence quenching of eosin Y

An easy, verified spectrofluorimetric approach was established for the investigation of moxifloxacin in pure forms, pharmaceutical preparations, and biological fluids. The approach involves forming a binary complex of moxifloxacin and eosin Y in an acetate buffer with a pH of 3.6. The highest quenching of eosin Y with moxifloxacin occurs at 545 nm. Several factors, such as pH, buffer type and concentration, and eosin Y concentration, were carefully studied. The calibration graph showed a linear relationship between fluorescence intensity and moxifloxacin concentrations between 0.2 and 10 µg mL^-1 with a correlation coefficient of 0.998. It was determined that the detection and quantification limits were 0.0322 µg mL^-1 and 0.0976 µg mL^-1, respectively. The impact of common excipients was investigated, but no interferences were discovered. Standard forms of moxifloxacin, pharmaceuticals, and biological samples have all been studied using the established methodology. The method, which successfully complied with ICH requirements, was used for the analysis of moxifloxacin in its pure form, pharmaceutical dosage forms, and biological samples. The percentage recoveries obtained were ranged from 99.50 to 102.50% for pharmaceutical preparations and from 100.50 to 102.50% for human blood plasma and urine. Proposed mechanisms for the reaction between moxifloxacin and eosin Y.

Potentiometric Determination of Moxifloxacin by Solid-Contact ISEs in Wastewater Effluents

In recent years, the use of ion-selective membranes in the sensing and assessment of environmental contaminants has become a critical goal. Using sodium tetraphenylborate (TPB) and phosphotungstic acid (PTA) as ion-pairing agents, two sensitive and selective sensors were manufactured to evaluate the electrochemical response of moxifloxacin hydrochloride (MOX). The optimal electrochemical behavior was attained by fine-tuning all assay parameters. The manufactured membranes’ performance was optimal in a pH range from 1.0 to 5.0 with a linearity between 1 × 10−6 M and 1 × 10−2 M. The MOX–TPB and MOX–PTA membrane electrodes have Nernstian slopes of 59.2 ± 0.60 mV/decade and 58.4 ± 0.50 mV/decade, respectively. The proposed method was used to determine MOX in its pure form as well as real pharmaceutical wastewater effluents. The fabricated electrodes were effectively applied for the sensitive and selective determination of MOX in actual wastewater effluents without the need for any pre-treatment processes.

A ratiometric fluorescence platform based on carbon dots for visual and rapid detection of copper(II) and fluoroquinolones

A simple smartphone-integrated ratiometric fluorescent sensing system for visual determination of copper ions (Cu²⁺) and fluoroquinolones (FQs) was developed based on carbon dots (CDs) which were synthesized through the high-temperature pyrolysis of citric acid. In this system, with the fluorescence resonance energy transfer effect between CDs and 2,3-diaminophenazine (oxOPD), the detection of Cu²⁺ and ciprofloxacin (CIP, an example for FQs) was realized. Cu²⁺ catalyzes the oxidation of OPD to form oxOPD with yellow fluorescence, resulting in the quenching of CDs. In addition, CIP can inhibit the catalytic activity of Cu²⁺ and induce the recovery of CDs fluorescence. Under the excitation of 400 nm, the changes of CDs fluorescence at 472 nm and oxOPD fluorescence at 556 nm were monitored. The detection results showed that the sensing system exhibited good selectivity and sensitivity to Cu²⁺ and CIP with the limit of detection of 2.32 × 10^-8 mol L^-1 and 0.2 ng mL^-1, respectively. In addition, a smartphone was developed as a portable analyzer to capture the change of fluorescence color and quickly analyze the concentration of Cu²⁺ and CIP. The proposed smartphone-based sensing platform has satisfactory sensitivity, and it has application prospects for detecting Cu²⁺ and FQs in food safety monitoring.

Moxifloxacin Hydrochloride Electrochemical Detection at Gold Nanoparticles Modified Screen-Printed Electrode

It appeared that either the carbon paste or the screen-printed carbon electrodes that were modified with gold nanoparticles (AuNPs) gave rise to the largest current responses after a rapid screening of various nanomaterials as modifiers of carbon composite electrodes in view of designing an electrochemical sensor for Moxifloxacin Hydrochloride (Moxi). The screen-printed electrode (SPE) support was preferred over the carbon paste one for its ability to be used as disposable single-use sensor enabling the circumvention of the problems of surface fouling encountered in the determination of Moxi. The response of AuNPs modified SPE to Moxi was investigated by cyclic voltammetry (CV) (including the effect of the potential scan rate and the pH of the medium), chronoamperometry, and differential pulse voltammetry (DPV) after morphological and physico-chemical characterization. DPV was finally applied to Moxi detection in phosphate buffer at pH 7, giving rise to an accessible concentration window ranging between 8 µM and 0.48 mM, and the detection and quantification limits were established to be 11.6 µM and 38.6 µM, correspondingly. In order to estimate the applicability of Moxi identification scheme in actual trials, it was practiced in a human baby urine sample with excellent recoveries between 99.8 % and 101.6 % and RSDs of 1.1-3.4%, without noticeable interference.

A Validated Spectrofluorimetric Method for the Determination of Moxifloxacin in Its Pure Form, Pharmaceutical Preparations, and Biological Samples

This research work presents a simple, sensitive, selective, economic, and widely applicable and interferences-free spectrofluorimetric method estimating moxifloxacin in the pure form, commercial formulations and biological samples. The method is based on the reaction of moxifloxacin with Ce(IV) in an acidic medium to generate fluorescent active species Ce(III). The excitation and emission of the fluorescent species are 250 and 362 nm, respectively. Different variables that might influence the oxidation of moxifloxacin, including the Ce(IV) concentration and volume, the effect of temperature and the heating time, the type of acids and its concentration were analyzed and boosted. The linearity was observed in the concentration range of 0.2 - 5.0 μg mL^-1 with a correlation coefficient of 0.9991. The limit of detection and the limit of quantification were calculated and observed to be 0.016 and 0.056 μg mL^-1 respectively. The effects of the common excipients and some co-administrated drugs usually used in the determination of moxifloxacin were investigated, and no interferences were noted. The planned method has been successfully practical for the analysis of moxifloxacin in its pure form, in pharmaceutical products and in biological samples. The obtained percent recoveries ranged from 95.50 to 101.37% for pharmaceutical products and from 95.15 to 103.18% for human blood plasma and urine.

Silver nanoparticles enhanced fluorescence for sensitive determination of fluoroquinolones in water solutions

A new type of silver nanoparticle (AgNPs) was prepared with simple and fast methods and low-toxic compounds. With the addition of different concentrations of AgNPs, the effects of AgNPs on the fluorescence properties of three different kinds of fluoroquinolones (enrofloxacin ENR, lomefloxacin LMF and norfloxacin NOR) in water solutions were studied, respectively. The experimental results demonstrated that the fluorescence intensity for each of the fluoroquinolones (FQ)was firstly enhanced and then quenched with the increased concentration of AgNPs in water solutions. The possible mechanisms about the AgNPs on the fluorescence behaviors of each FQ were also investigated, respectively. In addition, new silver enhanced nanoparticles materials fluorescence methods were established for the separate determination of ENR, LMF and NOR in water solutions. As compared with the identical control fluorimetric methods with no addition of AgNPs, the new enhanced fluorimetic methods were also investigated, respectively. The experimental results indicated that the new enhanced methods could detect lower concentrations of ENR, LMF and NOR in water solutions. Moreover, the newly enhanced fluorimetric methods were validated and successfully applied for the quantitative assay of ENR, LMF and NOR in different kinds of medicinal preparations, respectively.

Simultaneous Determination of Moxifloxacin and Flavoxate by RP-HPLC and Ecofriendly Derivative Spectrophotometry Methods in Formulations

Simple, fast, and precise reversed-phase (RP)-high-performance liquid chromatography (HPLC) and two ecofriendly spectrophotometric methods were established and validated for the simultaneous determination of moxifloxacin HCl (MOX) and flavoxate HCl (FLX) in formulations. Chromatographic methods involve the separation of two analytes using an Agilent Zorbax SB C18 HPLC column (150 mm × 4.6 mm; 5 µm) and a mobile phase consisting of phosphate buffer (50 mM; pH 5): methanol: acetonitrile in a proportion of 50:20:30 v/v, respectively. Valsartan was used as an internal standard. Analytes were monitored by measuring the absorbance of elute at 299 nm for MOX and 250 nm for FLX and valsartan. Two environmentally friendly spectrophotometric (first derivative and ratio first derivative) methods were also developed using water as a solvent. For the derivative spectrophotometric determination of MOX and FLX, a zero-crossing technique was adopted. The wavelengths selected for MOX and FLX were −304.0 nm and −331.8 nm for the first derivative spectrophotometric method and 358.4 nm and −334.1 nm for the ratio first-derivative spectrophotometric method, respectively. All methods were successfully validated, as per the International Conference on Harmonization(ICH) guidelines, and all parameters were well within acceptable ranges. The proposed analytical methods were successfully utilized for the simultaneous estimation of MOX and FLX in formulations.

Fiber-Enhanced Raman Sensing of Cefuroxime in Human Urine

Fiber-enhanced Raman spectroscopy was developed for the chemically selective and sensitive quantification of the important antibiotic cefuroxime in human urine. A novel optical sensor fiber was drawn and precisely prepared. In this fiber structure, light is strongly confined in the selectively filled liquid core, and the Raman scattered signal is collected with unprecedented efficiency over an extended interaction length. The filling, emptying, and robustness are highly improved due to the large core size (>30 μm). Broadband step-index guidance allows the free choice of the most suitable excitation wavelength in complex body fluids. The limit of detection of cefuroxime in human urine was improved by 2 orders of magnitude (to μM level). The quantification of cefuroxime was achieved in urine after oral administration. This method has great potential for the point-of-care monitoring of antibiotics concentrations and is an important step forward to enable clinicians to rapidly adjust doses.

Development and validation of sensitive kinetic spectrophotometric method for the determination of moxifloxacin antibiotic in pure and commercial tablets

New, accurate, sensitive and reliable kinetic spectrophotometric method for the assay of moxifloxacin hydrochloride (MOXF) in pure form and pharmaceutical formulations has been developed. The method involves the oxidative coupling reaction of MOXF with 3-methyl-2-benzothiazolinone hydrazone hydrochloride monohydrate (MBTH) in the presence of Ce(IV) in an acidic medium to form colored product with lambda max at 623 and 660 nm. The reaction is followed spectrophotometrically by measuring the increase in absorbance at 623 nm as a function of time. The initial rate and fixed time methods were adopted for constructing the calibration curves. The linearity range was found to be 1.89-40.0 μg mL(-1) for initial rate and fixed time methods. The limit of detection for initial rate and fixed time methods is 0.644 and 0.043 μg mL(-1), respectively. Molar absorptivity for the method was found to be 0.89×10(4) L mol(-1) cm(-1). Statistical treatment of the experimental results indicates that the methods are precise and accurate. The proposed method has been applied successfully for the estimation of moxifloxacin hydrochloride in tablet dosage form with no interference from the excipients. The results are compared with the official method.

On the performance of multiway methods for simultaneous quantification of two fluoroquinolones in urine samples by fluorescence spectroscopy and second-order calibration strategies

In the present work, the analytical performance of three multi-way algorithms has been evaluated. The proposed analytical problem was the simultaneous determination of moxifloxacin and ciprofloxacin in human urine samples using fluorescence spectroscopy. Parallel factor analysis (PARAFAC), self-weighted alternating trilinear decomposition (SWATLD) and unfolded partial least squares combined with the residual bilinearization procedure (U-PLS/RBL) have been compared, regarding their ability to solve the proposed problem. In this study, "second-order advantage" was also exploited for the mentioned algorithms through different calibration strategies. The three-way data was obtained via fluorescence spectroscopy, so that excitation-emission matrices (EEM) of the samples were recorded as the analytical signals. The accuracy and precision of each individual algorithm for analyzing the drugs in urine samples were compared using root mean square error of prediction (RMSEP), recovery and elliptical joint confidence region (EJCR) plots. The results revealed that each of the three algorithms could be applied for determination of moxifloxacin and ciprofloxacin, despite different EEM subsets and calibration strategies. However, better analytical performances were observed through PARAFAC and U-PLS/RBL modeling for MOX and CIP, respectively. So, by coupling the multi-way decomposition algorithms with fluorescence spectroscopy, a main part of preliminary sample preparation steps can be eliminated and experimental procedure might be significantly simplified, while achieving desirable analytical performance.

Potentiometric determination of moxifloxacin in some pharmaceutical formulation using PVC membrane sensors

BACKGROUND

The construction and electrochemical response characteristics of Poly (vinyl chloride) membrane sensors for moxifloxacin HCl (MOX) are described. The sensing membranes incorporate ion association complexes of moxifloxacin cation and sodium tetraphenyl borate (NaTPB) (sensor 1), phosphomolybdic acid (PMA) (sensor 2) or phosphotungstic acid (PTA) (sensor 3) as electroactive materials.

RESULTS

The sensors display a fast, stable and near-Nernstian response over a relative wide moxifloxacin concentration range (1 × 10(-2) - 4.0 × 10(-6), 1 × 10(-2) - 5.0 × 10(-6), 1 × 10(-2) - 5.0 × 10(-6) M), with detection limits of 3 × 10(-6), 4 × 10(-6) and 4.0 × 10(-6) M for sensor 1, 2 and 3, respectively over a pH range of 6.0 - 9.0. The sensors show good discrimination of moxifloxacin from several inorganic and organic compounds. The direct determination of 400 μg/ml of moxifloxacin show an average recovery of 98.5, 99.1 and 98.6% and a mean relative standard deviation of 1.8, 1.6 and 1.8% for sensors 1, 2 and 3 respectively.

CONCLUSIONS

The proposed sensors have been applied for direct determination of moxifloxacin in some pharmaceutical preparations. The results obtained by determination of moxifloxacin in tablets using the proposed sensors are comparable favorably with those obtained using the US Pharmacopeia method. The sensors have been used as indicator electrodes for potentiometric titration of moxifloxacin.

Moxifloxacin hydrochloride

A comprehensive profile of moxifloxacin HCl with 198 references is reported. A full description including nomenclature, formulae, elemental analysis, and appearance is included. Methods of preparation for moxifloxacin HCl, its intermediates, and derivatives are fully described. In addition, the physical properties, analytical methods, stability, uses and applications, and pharmacology of moxifloxacin HCl are also discussed.

Simultaneous determination of moxifloxacin and cefixime by first and ratio first derivative ultraviolet spectrophotometry

BACKGROUND

The new combination of moxifloxacin HCl and cefixime trihydrate is approved for the treatment of lower respiratory tract infections in adults. At initial formulation development and screening stage a fast and reliable method for the dissolution and release testing of moxifloxacin and cefixime were highly desirable. The zero order overlaid UV spectra of moxifloxacin and cefixime showed >90% overlapping. Hence, simple, accurate precise and validated two derivative spectrophotometric methods have been developed for the determination of moxifloxacin and cefixime.

METHODS

In the first derivative spectrophotometric method varying concentration of moxifloxacin and cefixime were prepared and scanned in the range of 200 to 400 nm and first derivative spectra were calculated (n = 1). The zero crossing wavelengths 287 nm and 317.9 nm were selected for determination of moxifloxacin and cefixime, respectively. In the second method the first derivative of ratio spectra was calculated and used for the determination of moxifloxacin and cefixime by measuring the peak intensity at 359.3 nm and 269.6 nm respectively.

RESULTS

Calibration graphs were established in the range of 1-16 μg /mL and 1-15 μg /mL for both the drugs by first and ratio first derivative spectroscopic methods respectively with good correlation coefficients. Average accuracy of assay of moxifloxacin and cefixime were found to be 100.68% and 98 93%, respectively. Relative standard deviations of both inter and intraday assays were less than 1.8%. Moreover, recovery of moxifloxacin and cefixime was more than 98.7% and 99.1%, respectively.

CONCLUSIONS

The described derivative spectrophotometric methods are simple, rapid, accurate, precise and excellent alternative to sophisticated chromatographic techniques. Hence, the proposed methods can be used for the quality control of the cited drugs and can be extended for routine analysis of the drugs in formulations.

validated microbiological and HPLC methods for the determination of moxifloxacin in pharmaceutical preparations and human plasma

The article presents a comparison between microbiological and high performance liquid chromatographic (HPLC) assays for quantification of moxifloxacin in tablets, ophthalmic solutions and human plasma. The microbiological method employed a cylinder-plate agar diffusion assay using a strain of Esherichia coli ATCC 25922 as the test organism and phosphate buffer (pH8) as the diluent. The calibration curves were linear (R² > 0.98) over a concentration range of 0.125 to 16 µgml^-1. The within day and between days precisions were ≤ 4.47% and ≤ 6.39% respectively. Recovery values were between 89.4 and 110.2%. The HPLC assay used Hypersil^® BDS C₁₈ reversed phase column (250×4.6 mm, 5µm) with a mobile phase comprising 20 mM ammonium dihydrogen orthophosphate (pH3) and acetonitrile (75:25) and flowing at 1.5 ml/min. The detection was at 295nm. The calibration curves were linear (R² > 0.999) over the range of 0.125 to 16 µg ml^-1. The within day and between days precisions were ≤ 4.07% and ≤ 5.09% respectively. Recovery values were between 97.7 and 107.6%. Similar potencies were obtained after the analysis of moxifloxacin tablets and ophthalmic solutions by both methods. Also pharmacokinetic parameters were calculated after the analysis of plasma samples of six male healthhy volunteers by both validated methods.

A 5-kg time-resolved luminescence photometer with multiple excitation sources

A luminescence photometer was developed based on lanthanide-sensitized luminescence to detect environmental pollutants and residues in foods including, in particular, two classes of antibiotics: tetracyclines and fluoroquinolones. Multiple excitation sources, a xenon flashlamp and ultraviolet light-emitting diodes (UV LEDs), were used to their advantages. A photomultiplier tube module, gated to reject time-domain interferences, was used as a photodetector. Using danofloxacin as a model analyte, luminescence signal was linear in more than three decades (0.5-2000 ng/mL) with R(2) > 0.998 in each decade. This photometer achieved a limit of detection of 2.0 ng/mL with 1.3% average relative standard deviation. It is field deployable at 4.6 kg and 15 W power consumption.

Spectrofluorimetric study of the interaction between europium(III) and moxifloxacin in micellar solution and its analytical application

A sensitive spectrofluorimetric method has been developed for the determination of moxifloxacin (MOX) using europium(III)-MOX complex as a fluorescence probe in the presence of an anionic surfactant, sodium dodecyl benzene sulfonate (SDBS). The fluorescence (FL) intensity of Eu(3+) was enhanced by complexation with MOX at 614 nm after excitation at 373 nm. The FL intensity of the Eu(3+)-MOX complex was significantly intensified in the presence of SDBS. Under the optimum conditions, it was found that the enhanced FL intensity of the system showed a good linear relationship with the concentration of MOX over the range of 1.8 × 10(-11)-7.3 × 10(-9) g mL(-1) with a correlation coefficient of 0.9998. The limit of detection of MOX was found to be 2.8 × 10(-12) g mL(-1) with relative standard deviation (RSD) of 1.25% for 5 replicate determination of 1.5 × 10(-8) g mL(-1) MOX. The proposed method is simple, offers higher sensitivity with wide linear range and can be successfully applied to determine MOX in pharmaceutical and biological samples with good reproducibility. The luminescence mechanism is also discussed in detail with ultraviolet absorption spectra.

Simultaneous determination of proline and pipemidic acid in human urine by capillary electrophoresis with electrochemiluminescence detection

Pipemidic acid is extensively used in the treatment of Gram-negative urinary tract infections, and the contents of proline in human urine vary in association with chronic uremia. The simultaneous determination of pipemidic acid and proline in human urine is of significance for quality control of the dosage and clinical study. The coupling of Ru(bpy)(3)(2+)-based electrochemiluminescence detection with capillary electrophoresis was developed for the simultaneous determination of proline and pipemidic acid in human urine. Parameters related to the separation and detection were investigated and optimized. The standard curves were linear between 0.1 and 90 µg mL(-1) for proline and between 0.4 and 100 µg mL(-1) for pipemidic acid. Underoptimized conditions, the detection limits (3σ) were 0.02 µg mL(-1) for proline and 0.06 µg mL(-1) for pipemidic acid. Relative standard derivations for the electrochemiluminescence intensity and the migration time were 3.2 and 0.9% for proline and 3.7 and 1.2% for pipemidic acid, respectively. The developed method was successfully applied to determine proline and pipemidic acid in human urine. The result showed that the content and decreasing rates of proline in urine for male were higher than that for female, and the content and decreasing rate of pipemidic acid in urine for male and female were consistent, respectively.

Spectrofluorimetric determination of fluoroquinolones in pharmaceutical preparations

Simple, rapid and highly sensitive spectrofluorimetric method is presented for the determination of four fluoroquinolone (FQ) drugs, ciprofloxacin, enoxacin, norfloxacin and moxifloxacin in pharmaceutical preparations. Proposed method is based on the derivatization of FQ with 4-chloro-7-nitrobenzofurazan (NBD-Cl) in borate buffer of pH 9.0 to yield a yellow product. The optimum experimental conditions have been studied carefully. Beer's law is obeyed over the concentration range of 23.5-500 ng mL(-1) for ciprofloxacin, 28.5-700 ng mL(-1) for enoxacin, 29.5-800 ng mL(-1) for norfloxacin and 33.5-1000 ng mL(-1) for moxifloxacin using NBD-Cl reagent, respectively. The detection limits were found to be 7.0 ng mL(-1) for ciprofloxacin, 8.5 ng mL(-1) for enoxacin, 9.2 ng mL(-1) for norfloxacin and 9.98 ng mL(-1) for moxifloxacin, respectively. Intra-day and inter-day relative standard deviation and relative mean error values at three different concentrations were determined. The low relative standard deviation values indicate good precision and high recovery values indicate accuracy of the proposed methods. The method is highly sensitive and specific. The results obtained are in good agreement with those obtained by the official and reference method. The results presented in this report show that the applied spectrofluorimetric method is acceptable for the determination of the four FQ in the pharmaceutical preparations. Common excipients used as additives in pharmaceutical preparations do not interfere with the proposed method.

Atomic absorption spectroscopic, conductometric and colorimetric methods for determination of some fluoroquinolone antibacterials using ammonium reineckate

Three accurate, rapid and simple atomic absorption spectrometric (AAS), conductometric and colorimetric methods were developed for the determination of gatifloxacin (GTF), moxifloxacin (MXF) and sparfloxacin (SPF). The proposed methods depend upon the reaction of ammonium reineckate with the studied drugs to form stable precipitate of ion-pair complexes, which was dissolved in acetone. The pink coloured complexes were determined either by AAS or colorimetrically at lambda(max) 525 nm directly using the dissolved complex. Using conductometric titration, the studied drugs could be evaluated in 50% (v/v) acetone. The optimizations of various experimental conditions were described. Optimum concentration ranges for the determination of GTF, MXF and SPF were 5.0-150, 40-440 microg mL(-1) and 0.10-1.5 mg mL(-1) using atomic absorption (AAS), conductometric and colorimetric methods, respectively. Detection and quantification limits are ranges from 1.5 to 2.3 microg mL(-1) using AAS method or 30-45 microg mL(-1) using colorimetric method. The proposed procedures have been applied successfully to the analysis of these drugs in pharmaceutical formulations and the results are favourably comparable to the reference methods.

Validated spectrophotometric methods for the estimation of moxifloxacin in bulk and pharmaceutical formulations

New, simple, cost effective, accurate and reproducible UV-spectrophotometric methods were developed and validated for the estimation of moxifloxacin in bulk and pharmaceutical formulations. Moxifloxacin was estimated at 296 nm in 0.1N hydrochloric acid (pH 1.2) and at 289 nm in phosphate buffer (pH 7.4). Beer's law was obeyed in the concentration range of 1-12 microg ml(-1) (r2=0.9999) in hydrochloric acid and 1-14 microg ml(-1) (r2=0.9998) in the phosphate buffer medium. The apparent molar absorptivity and Sandell's sensitivity coefficient were found to be 4.63 x 10(4) l mol(-1) cm(-1) and 9.5 ng cm(-2)/0.001 A in hydrochloric acid; and 4.08 x 10(4) l mol(-1) cm(-1) and 10.8 ng cm(-2)/0.001 A in phosphate buffer media, respectively indicating the high sensitivity of the proposed methods. These methods were tested and validated for various parameters according to ICH guidelines. The detection and quantitation limits were found to be 0.0402, 0.1217 microg ml(-1) in hydrochloric acid and 0.0384, 0.1163 microg ml(-1) in phosphate buffer medium, respectively. The proposed methods were successfully applied for the determination of moxifloxacin in pharmaceutical formulations (tablets, i.v. infusions, eye drops and polymeric nanoparticles). The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation <2%), while being simple, cheap and less time consuming and hence can be suitably applied for the estimation of moxifloxacin in different dosage forms and dissolution studies.

Determination of norfloxacin in rat liver perfusate using capillary electrophoresis with laser-induced fluorescence detection

A capillary zone electrophoresis method has been developed for the direct determination of norfloxacin in the physiological perfusate of isolated rat liver. Norfloxacin and the internal standard triamterene were detected using laser-induced fluorescence (LIF) detection with the excitation and emission wavelength of 325 and 435 nm, respectively. The background electrolyte (BGE) was 50 mM phosphate buffer (pH 4.6). The effect of pH and concentration of BGE on the electrophoretic migration and fluorescence response of analytes were examined. Calibration curves were linear over a wide range of 0.01-100 microg/mL. The limit of quantitation was 0.01 microg/mL. The intra- and inter-day relative standard deviation was 3.7%, or less, and the accuracy was 93.2% of the nominal concentration. No endogenous substances were found to interfere. The method was used to characterize the steady-state and transient pharmacokinetics of norfloxacin in the rat liver.

Effective separation and simultaneous determination of seven fluoroquinolones by capillary electrophoresis with diode-array detector

A simple, rapid and accurate method has been developed for effective separation and simultaneous determination of lomefloxacin, gatifloxacin, enoxacin, ciprofloxacin, ofloxacin, enrofloxacin and pefloxacin residues in porcine tissue by capillary electrophoresis with diode-array detector. The separation conditions were investigated and optimized. The sample was extracted with acetonitrile, and a mixture consisted of 25 mM NaH(2)PO(4), 25 mM Na(2)B(4)O(7) and 25 mM H(3)BO(3) (pH 9.0) was used as a running buffer. A linear relationship between concentration and peak area for each compound was obtained in the concentration range of 0.5-100 mg/L with a correlation coefficient greater than 0.9994. For analysis of porcine tissue, the detection limits of lomefloxacin, gatifloxacin, enoxacin, ciprofloxacin, ofloxacin, enrofloxacin and pefloxacin were 0.013, 0.012, 0.023, 0.040, 0.037, 0.035 and 0.034 mg/kg, respectively. The recoveries are in the range of 72-93%. The intra-day precision is less than 5%, and the inter-day precision is less than 10%. The proposed method has high resolution, speed and the extremely small sample volume required. It can permit to confirm the presence of the studied seven fluoroquinolones in porcine tissue at the required maximum residue limit (MRL) level.

High-performance liquid chromatography assay for moxifloxacin: Pharmacokinetics in human plasma

A sensitive high-performance liquid chromatographic (HPLC) method for the determination of moxifloxacin in human plasma using fluorescence detection was developed. The drug and an internal standard (norfloxacin) were subjected to precolumn derivatization with 4-chloro-7-nitrobenzodioxazole (NBD-CI). The chromatographic separation was achieved by HPLC using a mixture of acetonitrile-10 mM orthophosphoric acid (pH 2.5) (80:20, v/v) as the mobile phase with isocratically system, a C18 column. The derivative is highly fluorescent at 537 nm, being excited at 464 nm. The linear and reproducible calibration curve over the range was 15-2700 ng/mL of moxifloxacin in human plasma. The limits of detection and quantitation were 6 and 15 ng/mL, respectively. This method was applied in pharmacokinetic studies moxifloxacin preparations in healthy volunteers.

Moxifloxacin and azithromycin but not amoxicillin protect human respiratory epithelial cells against streptococcus pneumoniae in vitro when administered up to 6 hours after challenge

We determined the protective effect of moxifloxacin, azithromycin, and amoxicillin against Streptococcus pneumoniae infection of respiratory cells. Moxifloxacin and azithromycin effectively killed intracellular S. pneumoniae strains and protected respiratory epithelial cells significantly even when given 6 h after S. pneumoniae challenge. Amoxicillin was less effective.

Stability Indicating Methods for the Determination of Some Fluoroquinolones in the Presence of Their Decarboxylated Degradates

Two stability-indicating methods, namely densitometric TLC and derivative spectrophotometry for the determination of the fluoroquinolone antibacterials lomefloxacin (Lfx), moxifloxacin (Mfx), and sparfloxacin (Sfx) in the presence of their acid degrades are described. Acid degradation was adopted and the main decarboxylated product separated by TLC. Degradation products were identified confirming a previously mentioned degradation scheme. The densitometric method is based on the separation of the intact drug from its acid degradation product on silica gel G plates using different mobile phases and the spots of the intact drugs were scanned at 288, 290, and 292 nm for Lfx, Mfx, and Sfx, respectively. The derivative spectrophotometric method utilizes first derivative D(1) UV spectrophotometry with zero crossing points at 295.2 nm for Lfx, 280.4 and 303.4 nm for Mfx, and 280.8 nm for Sfx. Regression analysis of Beer's plots showed good correlation in the concentration ranges 0.2-1.2, 0.1-1.4, and 0.5-2.0 microg/spot for Lfx, Mfx, and Sfx, respectively, in the densitometric method and 2-16 microg/ml for all drugs in the derivative spectrophotometric method. The proposed methods were successfully applied for the determination of the investigated drugs in bulk powder with mean percentage accuracy ranges from 98.93 to 101.25% for the TLC method and from 98.18 to 100.35% for the D(1) method. The proposed methods were also applied for the determination of the investigated drugs in their pharmaceutical dosage forms and their validity was assessed using the standard addition technique with mean percentage recovery ranging from 100.25 to 101.70% in the TLC method and from 99.27 to 102.12% in the D(1) method. The selectivity of the proposed methods was tested by the analysis of laboratory-prepared mixtures containing different percentages of the studied drugs and their acid degrades. The proposed methods were found selective for the determination of the intact drugs in the presence of up to 90% of their degrades in the TLC method and 70% for Lfx and 90% for Mfx and Sfx in the D(1) method.

An ionizable chromophoric reagent for the analysis of primary amine-containing drugs by capillary electrophoresis

We found that ofloxacin acyl chloride is a potential chromophoric reagent for labeling amino analytes for capillary electrophoresis. Ofloxacin acyl chloride has a tertiary amino function in its structure and the derivatives from ofloxacin acyl chloride reacting with amino analytes can be ionized by an acid treatment and analyzed by simple capillary zone electrophoresis. Ofloxacin acyl chloride was used to derivatize model analytes (without chromophore) of amantadine (amino drug), tranexamic acid (non-protein amino carboxylic acid), glycine, and methionine (protein amino acids). The resulting derivatives were analyzed by capillary zone electrophoresis with ultraviolet detection (300 nm). The detection limits of the analytes studied were in the range of 1.0-2.5 microM (S/N = 3, injection 3 s). The precision (relative standard deviation) and accuracy (relative error) of the method for intra- and inter-day analyses of the analytes were respectively below 4.5% and 3.9%. Application of the method to the analysis of tranexamic acid in plasma proved feasible.

Overview of the status and applications of capillary electrophoresis to the analysis of small molecules

The status of capillary electrophoresis (CE) in the analysis of small molecules is reviewed and summarised with the illustrative use of recent literature references. Examples are cited in this review which demonstrate that CE is now a recognised and established technique in many industries, law courts and government regulatory agencies. Each of the principal areas of CE application in small molecule analysis are covered in sections which highlight the recent developments and possibilities within that area. Application areas include the analysis of pharmaceuticals, agrochemicals, chiral separations, and forensics is covered. This is an update to a previous review article [J. Chromatogr. A 856 (1999) 443] and covers papers published between 1999 and 2002. Technical developments and improvements, such as the advent of capillary array instrumentation for increased sample throughput, and improved detection options are described. Overall it is concluded that CE has become a recognised and established technique in many areas and is still within a period of development of both instrumentation and application which will continue to expand usage.

The benefit of the retrofitting of a conventional LC system to micro LC: a practical evaluation in the field of bioanalysis with fluorimetric detection

The interests in liquid micro-chromatography (higher column efficiencies, increase in sensitivity) are now well established. The enhancement of fluorimetric response induced by the reduction of the inner diameter of columns (4.6, 3.0, 1.0 and 0.3 mm respectively) coupled with adapted detection cells to control the loss of efficiency (8 micro L for the two first columns and 100 nL for the two smaller ones) has been studied in the bioanalytical field, using the plasma determination of native fluorescent antibacterial agents: fluoroquinolones. Ten-fold enhancement of the signal can easily be obtained when substituting a 0.3 mm i.d. column and 100 nL detection cell for a 4.6 mm i.d. column, and 8 micro L detection cell. In addition to inner diameter reduction, the detection cell geometry appears to be an essential parameter to obtain the best enhancement of the recorded signal. Hence, the enhancement of signal with micro-chromatography with fluorimetric detection appears to be a compromise between column inner diameter and flow cell volume reduction.