Simultaneous separation of five fluoroquinolone antibiotics by capillary zone electrophoresis

An AIE active luminogen derived using 2-hydroxy-1-naphthaldehyde and 3-hydroxy-2-naphthohydrazide for the detection of sparfloxacin and azithromycin

Herein, an aggregation-induced emission (AIE) luminogen (AIEgen) NANH was developed by condensing equimolar amounts of 2-hydroxy-1-naphthaldehyde and 3-hydroxy-2-naphthohydrazide. The AIE behaviour of NANH was explored in a mixed DMSO-H2O (HEPES buffer, pH 7.4, 10 mM) medium. The self-aggregates of NANH show enhanced emission at HEPES fractions (fHEPES) ≥70%. AIEgen NANH (fHEPES 95%, λex = 390 nm, λem = 490 nm) was applied for the fluorescence turn-off sensing of sparfloxacin and azithromycin. With the addition of different analytes, the fluorescence intensity of AIEgen NANH was quenched by sparfloxacin and azithromycin. No noticeable changes in the fluorescence of AIEgen NANH were observed with other added analytes. Experimental evidence supported that the fluorescence quenching of AIEgen NANH by sparfloxacin and azithromycin is static in nature. From the fluorescence titrations, the detection limits of AIEgen NANH were estimated down to 0.64 μM and 0.65 μM for sparfloxacin and azithromycin, respectively. Further, blood serum samples spiked with sparfloxacin and azithromycin were used to examine the analytical utility of AIEgen NANH.

Green Approach for Simultaneous Quantitative Analysis of Fluoroquinolones in the Environment using Three-Dimensional Fluorescence Coupled with Second-Order Calibration Method

In this study, a straightforward and quick analytical technique based on the self-weighted alternating trilinear decomposition (SWATLD) algorithm in conjunction with excitation-emission matrix (EEM) fluorescence for the simultaneous determination of the antibiotics levofloxacin (LVFX) and ciprofloxacin (CIP) in environmental waters and sediments was developed. This approach completely utilizes the "second-order advantage" and inherits the great sensitivity of classic fluorescence. It replaces or improves the conventional "physical/chemical separation" with "mathematical separation", enabling direct and quick quantification of the target analytes even in the presence of unknown interferences, greatly streamlining sample preparation procedures, consuming less solvent, and speeding up analysis time, and allows successful and environmentally friendly solution of overlapping fluorescence spectra of multiple components in complicated environmental matrices without cumbersome pretreatment steps and complex and expensive instrumentation. The limits of detection varied between 0.34 and 0.67 ng mL- 1, and the average spiking recoveries of LVFX and CIP in water and sediment ranged from 97.6 to 107.7% with relative standard deviations lower than 6.6%. The developed method shows the reliability of the technology and the ability to quickly detect trace antibiotics in lake water even in the presence of unidentified interferents.

Fast, Selective and Sensitive Fluorescence Detection of Levofloxacin, Fe3+ and Cu2+ Ions in 100% Aqueous Solution Via Their Reciprocal Recognition

The fluorescence detection of ions and pharmaceutical effluents by using organic chemosensors is a valuable surrogate to the currently existing expensive analytical methods. In this regard, the design of multi-functional chemosensors to recognize desirable guests is of utmost importance. In this study, we first show that levofloxacin (LVO) is able to use as a fluorescent chemosensor for the detection of biologically important Cu2+ (turn-off) and Fe3+ (turn-on) ions via independent signal outputs in 100% aqueous buffer solutions. Next, using the reciprocal recognition of LVO and Fe3+ provides a unique emission pattern for the detection of LVO. This approach exhibited a high specificity to LVO among various pharmaceutical samples, namely acetaminophen (AC), azithromycin (AZ), gemifloxacin (GEM) and ciprofloxacin (CIP) and also showed great anti-interference property in urine. The attractive features of this sensing system are availability, easy-to-use, high sensitivity (limit of detection = 18 nM for Cu2+, 22 nM for Fe3+ and 0.12 nM for LVO), rapid response (5 s) with an excellent selectivity.

Ultrasensitive levofloxacin electrochemical biosensor based on semiconducting covalent organic framework/poly-L-cysteine/triangular Ag nanoplates modified glassy carbon electrode

A novel electrochemical biosensor with excellent performance was fabricated for levofloxacin (LEV) detection, which adopted triangular Ag nanoplates (Tri-AgNP) confined in a poly-L-cysteine (poly-L-Cys) film and a semiconducting covalent organic framework (COF) as the electrochemical sensing material. The developed electrochemical sensor revealed excellent analytical properties because of its good electrical conductivity, fast electron transfer, and abundant bioactive site. Based on this, a linear relationship between the LEV concentration and the peak current response at 0.92 V was obtained under the optimal experimental conditions by differential pulse voltammetry (DPV), with a wide linear range of 0.05 to 600 μM and a low limit of detection (LOD) of 0.0061 μM. The prepared sensor also realized sensitive and accurate determination of LEV in human serum and urine samples by standard addition method, with satisfactory recoveries (97.1 to 104%) and a low relative standard deviation of less than 4.6%. These results indicated that the novel ternary system has a promising application in the development of electrochemical signal probe and electrochemical biosensing platform.

Classical versus chemometrics tools for spectrophotometric determination of fluocinolone acetonide, ciprofloxacin HCl and ciprofloxacin impurity-A in their ternary mixture

Green, simple, accurate and robust univariate and chemometrics assisted UV spectrophotometric approaches have been adopted and validated for concurrent quantification of fluocinolone acetonide (FLU), ciprofloxacin HCl (CIP) together with ciprofloxacin impurity-A (CIP imp-A) in their ternary mixture. Double-divisor ratio spectra derivative (DDRD) method has been used for determination of FLU. On the other hand, the first (D¹) and second (D²) derivative approaches have been applied for the quantification of CIP and CIP imp-A, respectively. For the ratio difference (RD), derivative ratio (DR), and mean centering of ratio spectra (MC) methods, CIP and its impurity A have been simultaneously determined. The acquired calibration plots were linear over the concentration range of 0.6-20.0 μg/mL, 1.0-40.0 μg/mL and 1.0-40.0 μg/mL for fluocinolone acetonide, ciprofloxacin HCl, and ciprofloxacin impurity-A, respectively. The chemometrics methods namely; partial least squares (PLS) and artificial neural networks (ANN) were used for the concurrent determination of the three adopted components via using twenty-five mixtures as calibration set and fifteen mixtures as validation one. The investigated approaches were validated in accordance with International Council for Harmonisation (ICH) guidelines, and statistically compared with the official ones. The proposed methods were acceptably applied to the examination of FLU and CIP in their pure powders and pharmaceutical ear drops.

Two Validated Chromatographic Methods for Determination of Ciprofloxacin HCl, One of its Specified Impurities and Fluocinolone Acetonide in Newly Approved Otic Solution

Two sensitive, selective and precise chromatographic methods have been established for concomitant quantification of ciprofloxacin HCl (CIP), fluocinolone acetonide (FLU) along with ciprofloxacin impurity A (CIP-imp A). The first method was thin-layer chromatography (TLC-densitometry) where separation was accomplished using TLC silica plates 60 G.F254 as a stationary phase and chloroform-methanol-33%ammonia (4.6:4.4:1, by volume) as a developing system. The obtained plates were scanned at 260 nm over concentration ranges of 1.0-40.0, 0.6-20.0 and 1.0-40.0 μg band-1 for CIP, FLU and CIP-imp A, respectively. The second method was based on high-performance liquid chromatography using a Zorbax ODS column (5 μm, 150 × 4.6 mm i.d.) where adequate separation was achieved through a mobile phase composed of phosphate buffer pH 3.6-acetonitrile (45:55, v/v) at flow rate 1.0 mL min-1 with ultraviolet detection at 254 nm. Linear regressions were obtained in the range of 1.0-40.0 μg mL-1 for CIP, 0.6-20.0 μg mL-1 for FLU and 1.0-40.0 μg mL-1 for CIP-imp A. The suggested methods were validated in compliance with the International Conference on Harmonization guidelines and were successfully applied for determination of CIP and FLU in bulk powder and newly marketed otic solution.

CE-DAD-MS/MS in the simultaneous determination and identification of selected antibiotic drugs and their metabolites in human urine samples

In this study, a new analytical method was developed and validated for the simultaneous analysis of antibiotic drugs (amoxicillin, cefotaxime, ciprofloxacin, clindamycin, linezolid, metronidazole) and their metabolites (amoxycilloic acid, amoxicillin diketopiperazine, 3-desacetyl cefotaxime lactone, clindamycin sulfoxide, ciprofloxacin piperazinyl-N4-sulfate, linezolid N-oxide, metronidazole-OH) in human urine. Capillary electrophoresis (CE) along with the tandem mass spectrometry (MS/MS) was used to determine and identify all analytes. Appropriate conditions for MS/MS measurements along with the use of the central composite design were optimized. The effects of different analytical conditions (the composition, the concentration, and the pH value of the background electrolyte, the time and pressure of the injection, the capillary temperature and influence of the organic modifier) on the migration and separation of antibiotic drugs and metabolites were examined using the CE-DAD. The analytical procedure was linear for concentrations ranging from 20 to 1000 ng/mL, with determination coefficients higher than 0.99 for all the analytes. The validated analytical procedure was then applied to the measurement of antibiotic drugs and their metabolites in human urine samples.

Determination of levofloxacin, ciprofloxacin, moxifloxacin and gemifloxacin in urine and plasma by HPLC-FLD-DAD using pentafluorophenyl core-shell column: Application to drug monitoring

Concentrations of fluoroquinolones, which are used in the treatment of many bacterial infections, should be monitored in biological fluids as they exhibit concentration-dependent bactericidal activity. In this study, a liquid chromatography method for the determination of levofloxacin, ciprofloxacin, moxifloxacin and gemifloxacin in human urine and plasma was developed for the first time. The efficiency of five different columns for the separation of these fluoroquinolones was compared. Experimental parameters that affect the separation, such as percentage of organic solvent, pH, temperature, gradient shape and detector wavelength, were optimized by a step-by-step approach. Using a pentafluorophenyl core-shell column (100 × 4.6 mm, 2.7 μm), the separation of four analytes was accomplished in <7.5 min. The developed method was validated for the determination of analytes in both urine and plasma with respect to sensitivity, specificity, linearity (r ≥ 0.9989), recovery (79.46-102.69%), accuracy, precision and stability (85.79-111.07%). The intra- and inter-day accuracies were within 89.55-111.94% with relative standard deviations of 0.35-8.05%. The feasibility of method was demonstrated by analyzing urine and plasma samples of patients orally receiving levofloxacin, ciprofloxacin or moxifloxacin. The developed method is suitable for therapeutic drug monitoring of these fluoroquinolones and can be applied to pharmacokinetic and toxicological studies.

Rapid and simultaneous determination of three fluoroquinolones in animal-derived foods using excitation-emission matrix fluorescence coupled with second-order calibration method

The matter of fluoroquinolone residues in various foods still arouses wide public concern nowadays. In the present work, the strategy of excitation-emission matrix (EEM) fluorescence data coupled with second-order calibration method based on alternating normalization-weighted error (ANWE) algorithm was used to determine ofloxacin, lomefloxacin and ciprofloxacin in milk powder, milk and beef. Owning the unique "second-order advantage", the ANWE-assisted analytical method was proved to successfully and eco-friendly resolve the overlapped fluorescence spectra of multi-component in complex food matrixes without tedious pretreatment steps and sophisticated high-cost instrumentations. The feasibility of the proposed method was validated by experiments. The average spiked recoveries of three fluoroquinolones range from 82.6% to 110.5% with relative standard deviations lower than 7.4%, and the limits of detection range from 0.18 and 2.41 ng mL^-1. For further evaluation, analytical figures of merit such as sensitivity and selectivity, as well as the RSDs of intra-day (≦10.6%) and inter-day (≦9.4%) were calculated. The satisfactory analytical results demonstrated that the proposed strategy could be a competitive alternative for simple, rapid and simultaneous determination of multiple fluoroquinolones in animal-derived food samples.

Fingerprint Spectrophotometric Methods for the Determination of Co-Formulated Otic Solution of Ciprofloxacin and Fluocinolone Acetonide in Their Challengeable Ratio

Six spectrophotometric methods were developed to determine a new single-dose otic solution known as "Otovel®," which consists of two components: the major one is ciprofloxacin (CIP) and the minor is fluocinolone acetonide (FLU). The ratio of (CIP) and (FLU) in Otovel® is 12 : 1, which is considered a challengeable ratio for UV determination. Thus, spectrum addition as a sample enrichment technique was required for the analysis of (FLU) low concentration. All these methods were capable of resolving the spectra for each component in D 0 belonging to the fingerprint resolution technique. The former absorptivity centering (a-centering) method was recently developed in 2018; it was effectively applied for its solution of both binary components in Otovel®, while another method, ratio subtraction (RS), is considered as an original resolution method that could be applied to determine only one component in mixtures. However, the other four methods that are related to their original method (RS) were extended ratio subtraction (EXRS), constant multiplication (CM), unified constant subtraction (UCS), and spectrum subtraction (SS). They were also easily applied for completing the quantification of binary mixture drugs present in Otovel®. The linearity ranges were found to be 3.0-15.0 μg/mL for (CIP) and (FLU), respectively. All results acquired from the proposed methods were successfully estimated according to ICH criteria and were statistically compared with official ones where no differences were noticed.

Spectrophotometric strategies for the analysis of binary combinations with minor component based on isoabsorptive point's leveling effect: An application on ciprofloxacin and fluocinolone acetonide in their recently delivered co-formulation

Comparative study of the spectrophotometric strategies utilizing the isoabsorptive point present in overlapped absorption spectra of ciprofloxacin and fluocinolone acetonide in their recently delivered co-formulation, was presented. Four spectrophotometric approaches were developed, dependent on the determination of the leveling effect of isoabsorptive point in their zero order absorption spectra or its manipulated form ratio spectra as it retains an isosbestic point. The proposed strategy was based on determination of the total concentrations of the proposed drugs at iso-point, either via zero order or ratio spectra, while one of the recommended methods determined the concentration of the major component, so the concentration of the minor component was obtained by differentiation. The first, second and third methods are utilizing isoabsorptive point at zero order absorption spectrum to quantify total concentration of the cited component, while the major component could be selectively determined using either absorbance at its maxima (IsoP_D⁰-D⁰_max), or area under the peak method (IsoP_D⁰-AUC), or first derivative technique (IsoP_D⁰-D¹). The fourth method is ratio manipulated isoabsorptive point in ratio spectrum, namely the amplitude modulation method (AM), using an unified regression equation for the total and major component concentrations, separately. The four methods were applied practically for the analysis of the binary mixtures of ciprofloxacin hydrochloride (CIP) and fluocinolone acetonide (FLU) in a recently otic solution form in challengeable ratio12:1respectively, without the need of any previous stages such as separation, dilution or standard addition. The methods were successfully validated as per ICH guidelines. The outcomes data gained from those submitted techniques were statistically assimilated with official ones. However, no radical differences were noticed.

Application of a definitive screening design for the synthesis of a charge-transfer complex of sparfloxacin with tetracyanoethylene: spectroscopic, thermodynamic, kinetics, and DFT computational studies

Herein, a spectrochemical approach was adopted to study the charge-transfer (CT) complexation of sparfloxacin (SFX) with tetracyanoethylene (TCNE). In this study, a three-level design of experiments (DOE) involving a definitive screening design (DSD) was implemented. This is the first effort to operate this new category of design to determine a pharmaceutical compound in its pure form and in formulations. The proposed design allowed the establishment of a regression model that described the relation between the factorial input and the response surface. Moreover, two charge-transfer states (CTSs) were observed at 390 and 464 nm. The DFT calculations conducted using B3LYP/6-31+G showed that SFX had several donation sites (donor, D), whereas TCNE had two acceptor (A) sites. The two states were influenced differently by the experimental conditions as per the findings of the DSD analysis. In general, the diluting solvent had the largest impact. Probability plots, histograms, individual value plots, residual plots as well as analysis of variance (ANOVA) were delineated at the 95.0% confidence interval (CI). A Job's plot showed that a 1 : 1 complex was formed. The results were further confirmed using Benesi–Hildebrand plots. The proposed approach was proved to be linear in the range of 10–90 μg mL⁻¹ SFX when the absorbance was measured at 464 nm. Different set-ups were adopted for studying the reaction kinetics. Analytical method performance was assessed following the ICH guiding principles, and the results obtained were found to be satisfactory. Complex formation was found to be an exothermic reaction.

A spectrochemical approach was adopted to study the charge-transfer (CT) complexation of sparfloxacin (SFX) with tetracyanoethylene (TCNE). Definitive screening design (DSD) was used to investigate the reaction variables.

Analytical investigation of different mathematical approaches utilizing manipulation of ratio spectra

This work represents a comparative study of different approaches of manipulating ratio spectra, applied on a binary mixture of ciprofloxacin HCl and dexamethasone sodium phosphate co-formulated as ear drops. The proposed new spectrophotometric methods are: ratio difference spectrophotometric method (RDSM), amplitude center method (ACM), first derivative of the ratio spectra (¹DD) and mean centering of ratio spectra (MCR). The proposed methods were checked using laboratory-prepared mixtures and were successfully applied for the analysis of pharmaceutical formulation containing the cited drugs. The proposed methods were validated according to the ICH guidelines. A comparative study was conducted between those methods regarding simplicity, limitations and sensitivity. The obtained results were statistically compared with those obtained from the reported HPLC method, showing no significant difference with respect to accuracy and precision.

Analytical Methods for Determining Third and Fourth Generation Fluoroquinolones: A Review

ABSTRACT

Fluoroquinolones of the third and fourth generation posses wide bactericidal activity. Monitoring concentrations of antibacterial agents provides effective therapy and prevents the increase of bacterial resistance to antibiotics. The pharmacodynamic parameters that best describe fluoroquinalone activity are AUC/MIC and Cmax/MIC. Determining the level of this type of drug is essential to reach the effective concentration that inhibits the growth of bacteria. Determining the pharmaceutical formulation confirms the purity of a substance. Many methods have been developed to determine the level of these substances. They involve mainly the following analytical techniques: chromatography, capillary electrophoresis, and spectroscopy. The separation techniques were combined with different measuring devices, such as ultraviolet (UV), fluorescence detector (FLD), diode array detector (DAD), and mass spectrometry (MS). The analytical procedures require proper sample pre-conditioning such as protein precipitation, extraction techniques, filtration, or dilution. This paper reviews the reported analytical methods for the determining representatives of the third and fourth generation of fluoroquinolones. Attention was paid to pre-conditioning of the samples and the applied mobile phase. This report might be helpful in the selection of the proper procedure in determining the abovementioned drugs in different matrices.

GRAPHICAL ABSTRACT

Broad-Specificity Chemiluminescence Enzyme Immunoassay for (Fluoro)quinolones: Hapten Design and Molecular Modeling Study of Antibody Recognition

On the basis of the structural features of (fluoro)quinolones (FQs), pazufloxacin was first used as a generic immunizing hapten to raise a broad-specificity antibody. The obtained polyclonal antibody exhibited broad cross-reactivity ranging from 5.19% to 478.77% with 21 FQs. Furthermore, the antibody was able to recognize these FQs below their maximum residue limits (MRLs) in an indirect competitive chemiluminescence enzyme immunoassay (ic-CLEIA), with the limit of detection (LOD) ranging from 0.10 to 33.83 ng/mL. For simply pretreated milk samples with spiked FQs, the ic-CLEIA exhibited an excellent recovery with a range of 84.6-106.9% and an acceptable coefficient of variation below 15%, suggesting its suitability and reliability for the use of a promising tool to detect FQs. Meanwhile, comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) models, with statistically significant correlation coefficients (q(2)CoMFA = 0.559, r(2)CoMFA = 0.999; q(2)CoMSIA = 0.559, r(2)CoMSIA = 0.994), were established to investigate the antibody recognition mechanism. These two models revealed that in the antibody, the active cavity binding FQs' 7-position substituents worked together with another cavity (binding FQs' 1-position groups) to crucially endow the high cross-reactivity. This investigation will be significant for better exploring the recognition mechanism and for designing new haptens.

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.

Supramolecular interaction of Moxifloxacin and β-cyclodextrin spectroscopic characterization and analytical application

The supramolecular interaction of Moxifloxacin (Moxi) and β-cyclodextrin (β-CD) has been examined by UV-VIS, FTIR, H(1)NMR, SEM and fluorescence spectroscopy. The formation of inclusion complex has been confirmed on the base of changes of spectroscopy properties. The results showed that β-CD reacted with Moxi to form an inclusion complex. The Moxi and β-CD complex formed a host-guest complex in 1:1 stoichiometry and inclusion constant (K=3.95×10(2) L mol(-1)) was ascertained by the typical double reciprocal plots. Furthermore, the thermodynamic parameters (ΔH°, ΔS° and ΔG°) associated with the inclusion process were also determined. Based on the significant enhancement of the fluorescence intensity of Moxi produced through complex formation, a simple, accurate, rapid and highly sensitive spectrofluorometric method for the determination of Moxi in pharmaceutical formulation was developed. The measurement of relative fluorescence intensity was carried out at 464 nm with excitation at 289 nm. The factors affecting the inclusion complex formation were studied and optimized. Under the optimum reaction conditions, linear relationships with good correlation coefficients (0.99973) were in the concentration range of 10-60 ng/mL for spectrofluorimetry. The limit of detection (LOD) was found to be 1.6 ng/mL. The proposed method was successfully applied to the analysis of Moxi in pharmaceutical preparation.

Spectrophotometric determination of gemifloxacin mesylate, moxifloxacin hydrochloride, and enrofloxacin in pharmaceutical formulations using Acid dyes

SIMPLE, RAPID, AND EXTRACTIVE SPECTROPHOTOMETRIC METHODS WERE DEVELOPED FOR THE DETERMINATION OF SOME FLUOROQUINOLONES ANTIBIOTICS: gemifloxacin mesylate (GMF), moxifloxacin hydrochloride (MXF), and enrofloxacin (ENF) in pure forms and pharmaceutical formulations. These methods are based on the formation of ion-pair complexes between the basic drugs and acid dyes, namely, bromocresol green (BCG), bromocresol purple (BCP), bromophenol blue (BPB), bromothymol blue (BTB), and methyl orange (MO) in acidic buffer solutions. The formed complexes were extracted with chloroform and measured at 420, 408, 416, 415, and 422 nm for BCG, BCP, BPB, BTB, and MO, respectively, for GMF; at 410, 415, 416, and 420 nm for BCP, BTB, BPB, and MO, respectively, for MXF; and at 419 and 414 nm for BCG and BTB, respectively, in case of ENF. The analytical parameters and their effects are investigated. Beer's law was obeyed in the ranges 1.0-30, 1.0-20, and 2.0-24  μ g mL(-1) for GMF, MXF, and ENF, respectively. The proposed methods have been applied successfully for the analysis of the studied drugs in pure forms and pharmaceutical formulations. Statistical comparison of the results with the reference methods showed excellent agreement and indicated no significant difference in accuracy and precision.