Investigating the interaction of terbinafine with xanthenes dye for its feasible determination applying the resonance Rayleigh scattering technique

Utility of green chemistry for spectrofluorometric and spectrophotometric analysis of vericiguat via reaction with erythrocin B

Food colorant Erythrosine B (EB) is an antiviral xanthene dye with a wide range of uses as a colorant in cosmetics and medications. Its availability, affordability, quick labeling, and high sensitivity make it an excellent choice for spectrofluorometric and spectrophotometric examination of amine-based medications. Two quick and accurate spectrophotometric and spectrofluorometric methods were developed for the estimation of vericiguat in this case. To create an ion-pair complex at pH 4 using the Britton Robinson buffer, the suggested methods relied on the interaction between the amino groups of the medication under study and the phenolic group of EB. The quenching effect of the vericigaute drug of EB at excitation/emission wavelengths of 530.0/550.0 nm. This method demonstrated a limit of detection (LOD) of 0.036 µg/mL and a limit of quantification (LOQ) of 0.110 µg/mL, showing rectilinear response in the concentration range of 0.05-0.5 µg/mL. Additionally, the absorbance of the produced ion-pair complex was evaluated using the colorimetric approach at 560 nm, displaying a linearity range of 0.5-10.0 µg/mL with LOD = 0.428 µg/mL and LOQ = 1.298 µg/mL. The greenness of the developed approaches was determined by GAPT and AGREE software for evaluating the suggested methods.

Development of Eco-Friendly Scattering and Fluorimetric Methods for the Determination of Clemastine Through Its Interaction with Eosin Y: Assessment of Whiteness, Blueness, and Greenness Tools

For the first time, clemastine was estimated in this work utilizing two validated resonance Rayleigh scattering (RRS) and fluorimetric methods. The methods relied on forming an association complex in an acidic medium between eosin Y reagent and clemastine. In the spectrofluorimetric approach, the investigated drug was quantified by quenching the fluorescence-emission intensity of eosin Y at 543.5 nm. The RRS method relied on enhancing the RRS spectrum at 331.8 nm, which is produced when eosin Y interacts with clemastine. Suitable conditions were established for the reaction to achieve maximum sensitivity. The linear values obtained from the spectrofluorimetric approach and the RRS method fall into the ranges of 0.2-1.5 µg mL- 1 and 0.25-2.0 µg mL- 1, respectively. It was established that the detection limits for these methods were 0.045 µg mL- 1 and 0.059 µg mL- 1, respectively. The developed methodologies yielded acceptable recoveries when used to estimate the quantity of clemastine in its pharmaceutical tablet dosage form. Regarding the use of greener solvents that were chosen, the suggested and reported methods were compared with the help of the Green Solvents Selecting (GSST) tool for assessing hazardous solvents to achieve sustainability. Furthermore, analytical Eco scale and comprehensive assessments of whiteness, blueness, and greenness were carried out utilizing Modified NEMI, ComplexGAPI, and AGREE evaluation tools. Additionally, recently developed tools such as BAGI and RGB 12 were applied to assess the blueness and the whiteness of the suggested methods.

Full green assay of parenteral dosage forms of polymyxins utilizing xanthene dye: application to content uniformity testing

Due to the lack of other treatment options, a rebirth of polymyxins is urgently required. Colistin (also called polymyxin E) and polymyxin B are the only two examples of this antibiotic class that were effectively employed in such critical situations. In the present work, both of the two studied medications were quantified via a simple, green, and non-extracting spectrophotometric approach based on the formation of ion-pair complexes with Erythrosine B. Without using any organic solvents, the pink color of the created complexes was detected at wavelength = 558 nm. To achieve the highest intensity of absorbance, optimum conditions were established by the screening of many experimental factors such as pH, buffer volume, the volume of Erythrosine B, and the time consumed to undergo the reaction. For Colistin and Polymyxin B respectively, Beer-Lambert's law was observed at the concentration ranges of 1-6, 1-9 µg mL- 1. The technique was approved and validated following ICH recommendations. Lastly, the suggested approach has been successfully implemented to quantify the cited medications colorimetrically, for the first time, in their parenteral dosage forms with excellent recoveries. Also, Content uniformity testing was implemented.

Exploitation of erythrosine B as a fluorometric marker for lurasidone determination through electrostatic attraction; application to content uniformity test

A recently developed antipsychotic drug, lurasidone, was determined using a simple, sensitive, and eco-friendly spectrofluorimetric approach. The suggested approach was based on the quantifiable quenching impact of lurasidone on the inherent fluorescence of erythrosine B in an acidic environment employing a Teorell-Stenhagen buffer (pH 4). Following excitation at 530 nm, the quenching of erythrosine B fluorescence was monitored at 552 nm. The system variables were systematically optimized to enhance the formation of the lurasidone-erythrosine B ion pair for analytical purposes. A linear calibration graph was built in the range of 20-600 ng mL-1 with 0.9998 as a coefficient of correlation. The quantitation and detection limits were 13.5 and 4.5 ng/mL, respectively. The analytical validity of the designed approach was assessed with respect to International Council on Harmonization (ICH) guiding principles. The proposed methodology was employed with high recoveries for assessing lurasidone in bulk powder and its therapeutic tablet dosage form. Additionally, the uniformity of tablet formulations was tested using the developed approach. Finally, the established approach was assessed for its greenness using various tools.

An ingenious technique based on the usage of fluorone-based dye; pyrosin B in prucalopride assay in different matrices through an "on-off" dye native fluorescence probe

Prucalopride (PCD), is a modern medication approved by the United States in 2018 to alleviate constipation caused by motility issues. PCD demonstrates a strong affinity and selectivity toward the 5-HT4 receptor. The study here introduces a feasible, direct, non-extractive, and affordable pathway for PCD analytical tracking. The fluorimetric study is based on the on-off effect on the emission amplitude of fluorone-based dye (pyrosin B). In a one-pot experiment, the complex between PCD and pyrosin B is formed instantly in an acidic medium. Correlation between decreased pyrosin B emission and PCD concentrations provides a linear calibration plot from 50 to 900 ng/mL. PCD-dye complex system affecting variables were meticulously tuned. The values of the estimated limit of quantitation and limit of detection for the current methodology were 47.5 and 15.7 ng/mL, respectively. Conformity of the strategy validity was achieved by a comprehensive study of the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use criteria. The method was convincingly applied for PCD assay in tablets and content uniformity investigation. Furthermore, PCD tracking in the spiked biological fluid was applied. Finally, the method uses distilled water as dispersing medium which rise accommodation with the green chemistry principle.

Design of resonance Rayleigh scattering and spectrofluorimetric methods for the determination of the antihistaminic drug, hydroxyzine, based on its interaction with 2,4,5,7-tetraiodofluorescein: Evaluation of analytical eco-scale and greenness/whiteness algorithms

In this work, two validated approaches were used for estimating hydroxyzine HCl for the first time using resonance Rayleigh scattering (RRS) and spectrofluorimetric techniques. The suggested approaches relied on forming an association complex between hydroxyzine HCl and 2,4,5,7-tetraiodofluorescein (erythrosin B) reagent in an acidic media. The quenching in the fluorescence intensity of 2,4,5,7-tetraiodofluorescein by hydroxyzine at 551.5 nm (excitation = 527.5 nm) was used for determining the studied drug by the spectrofluorimetric technique. The RRS approach is based on amplifying the RRS spectrum at 348 nm upon the interaction of hydroxyzine HCl with 2,4,5,7-tetraiodofluorescein. The spectrofluorimetric methodology and the RRS methodology produced linear results within ranges of 0.15-1.5 μg ml-1 and 0.1-1.2 μg ml-1, respectively. LOD values for these methods were determined to be 0.047 μg ml-1 and 0.033 μg ml-1, respectively. The content of hydroxyzine HCl in its pharmaceutical tablet was estimated using the developed procedures with acceptable recoveries. Additionally, the application of four greenness and whiteness algorithms shows that they are superior to the previously reported method in terms of sustainability, economics, analytical performance, and practicality.

Utility of native emission quenching of erythrosine B for the determination of diltiazem in different dosage forms

This study introduces a practical and cost-effective method for tracking diltiazem (DLZ) analytically. It utilizes a fluorimetric approach that relies on the modulation of fluorescence intensity of a dye called erythrosine B. Through a one-pot experiment performed in an acidic environment, a complex is rapidly formed between DLZ and erythrosine B. By observing the decrease in erythrosine B emission, a linear calibration plot is established, enabling the detection and quantification of DLZ concentrations ranging from 40 to 850 ng/ml. The estimated limits of detection and quantitation were 10.5 and 32.1 ng/ml, respectively. The variables affecting the DLZ-dye complex system were carefully adjusted. The validity of the approach was confirmed through a thorough evaluation based on the criteria set by ICH guidelines. The accuracy and precision of the methodology were evaluated, and the standard deviation and relative standard deviation were below 2. The strategy was successfully employed to analyze DLZ in tablets and capsules, and no significant variation between the proposed and reported methods as the values of the estimated t-test and F-test at five determinations were below 2.306 and 6.338, respectively. Notably, the method adheres to the principle of green chemistry by utilizing distilled water as the dispersing medium.

Study on the interaction between erythrosine B and the cardiac drug amiodarone using fluorescence, scattering, and absorbance spectra and their analytical application

In an acidic buffered solution, erythrosine B can react with amiodarone to form an association complex, which not only generates great enhancement in resonance Rayleigh scattering (RRS) spectrum of erythrosine B at 346.5 nm but also results in quenching of fluorescence spectra of erythrosine B at λemission = 550.4 nm/λexcitation = 528.5 nm. In addition, the formed erythrosine B-amiodarone complex produces a new absorbance peak at 555 nm. The spectral characteristics of the RRS, absorbance, and fluorescence spectra, as well as the optimum analytical conditions, were studied and investigated. As a result, new spectroscopic methods were developed to determine amiodarone by utilizing erythrosine B as a probe. Moreover, the ICH guidelines were used to validate the developed RRS, photometric, and fluorimetric methods. The enhancements in the absorbance and the RRS intensity and the decrease in the fluorescence intensity of the used probe were proportional to the concentration of amiodarone in ranges of 2.5-20.0, 0.2-2.5, and 0.25-1.75 μg/mL, respectively. Furthermore, limit of detection values were 0.52 ng/mL for the spectrophotometric method, 0.051 μg/mL for the RRS method, and 0.075 μg/mL for the fluorimetric method. Moreover, with good recoveries, the developed spectroscopic procedures were applied to analyze amiodarone in its commercial tablets.

Green spectrophotometric and spectrofluorimetric determination of biperiden hydrochloride using erythrosine B sensing probe

Erythrosine B (EB) is a food colorant antiviral xanthene dye that has many applications as a color additive in pharmaceuticals and cosmetics. Its use as a sensor for spectrofluorimetric and spectrophotometric analysis of amine-based pharmaceuticals renders many advantages because of its availability, low cost, rapid labeling, and high sensitivity. Herein, two fast and sensitive spectrofluorimetric and spectrophotometric methods were established for the estimation of the anti-Parkinson drug, biperiden (BIP) hydrochloride (HCl), in its raw material and tablet forms. The proposed methods depended on the interaction between the phenolic group of EB and the tertiary amino group of the studied analyte to form an ion-pair complex at pH 4 using the Britton Robinson buffer. The spectrofluorimetric method is based on the measurement of the quenching power of BIP HCl on the fluorescence intensity of EB at λex/em = 527.0/550.9 nm. This method was rectilinear over the concentration range of 0.1-1.0 μg/mL with a limit of detection (LOD) = 0.017 μg/mL and a limit of quantification (LOQ) = 0.05 μg/mL. Meanwhile, the colorimetric method involved monitoring the absorbance of the formed ion-pair complex at 555 nm, showing a linearity range of 0.4-5.0 μg/mL with LOD = 0.106 μg/mL and LOQ = 0.322 μg/mL. The proposed methods were assessed for the greenness, indicating the greenness of the developed methods.

Utility of the food colorant erythrosine B as an effective green probe for quantitation of the anticancer sunitinib. Application to pharmaceutical formulations and human plasma

Sunitinib is a tyrosine kinase inhibitor used for the treatment of renal cell carcinoma and gastrointestinal stromal tumors. In this study, two spectroscopic methods, spectrofluorometric and spectrophotometric, were utilized to quantify sunitinib in different matrices. In method I, the native fluorescence of erythrosine B was quenched by forming ion-pair complex with increasing quantities of sunitinib. This approach was utilized for measuring sunitinib in its dosage forms and spiked plasma. After excitation at 528 nm, the quenching of fluorescence is linearly related to the concentration across the range of 0.05-0.5 μg mL-1 at 550 nm in Britton-Robinson buffer (pH 4.0), with a correlation value of 0.9999 and a high level of sensitivity with detection limit down to 10 ng mL-1 . Method II relies on spectrophotometric measurements of the produced complex at 550 nm across a range of 0.5-10.0 μg mL-1 , with good correlation value of 0.9999. This method has a detection limit down to 0.16 μg mL-1 . The proposed methodologies were validated according to International Conference on Harmonization (ICH) guidelines with satisfactory results. The stoichiometry of the reaction was determined through the application of Job's method, while the mechanism of quenching was investigated by employing the Stern-Volmer plot. The designated methods were used to estimate sunitinib in its capsules and in spiked human plasma. Additionally, the statistical analysis of the data revealed no substantial differences when compared to previous reported spectroscopic method. Green assessment tools provide further details about the eco-friendly nature of the methods.

Resonance Rayleigh scattering technique-using chitosan-capped gold nanoparticles, approaches spectrofluorimetric method for determination of Bentazone residual in water samples

In this study, a resonance Rayleigh scattering technique-based sensing method for detecting Bentazone residual in water samples has been developed. This technique was carried out using chitosan-capped gold nanoparticles with a spectrofluorimetric method. Experimental results revealed that the developed method could allow the detection of Bentazone residual as low as a concentration of 0.02 ng mL-1 within 50-sec time. Overall results confirmed the very low detection limit for measuring the Bentazone. The chitosan-capped gold nanoparticles as an excellent sensor were applied to measure and analyze Bentazone in water samples.

Validated spectrofluorimetric and resonance Rayleigh scattering methods for determining naftidrofuryl in varied pharmaceutical samples based on its interaction with erythrosin B

Naftidrofuryl is a vasodilator medication used for treating cerebral and peripheral vascular diseases. In this study, two spectroscopical techniques, spectrofluorimetric and resonance Rayleigh scattering (RRS), were utilized to quantify naftidrofuryl in its pharmaceutical samples. The developed methodologies in this study rely on a facile process of forming an association complex between erythrosine B reagent and naftidrofuryl under acidic conditions. The fluorimetric assay is based on the ability of naftidrofuryl to quench and decrease the native fluorescence intensity of the reagent when measured at λ emis . = 550 nm ( λ excit . = 526 nm). Under similar reaction conditions, the RRS method relies on the observed amplification in the RRS spectrum of the reagent at a wavelength of 577 nm following its interaction with naftidrofuryl. The methods exhibited linearity within the ranges 0.2-1.6 μg/ml (r2  = 0.999) and 0.1-1.4 μg/ml (r2  = 0.9994), with limit of quantitation values of 0.146 and 0.099 μg/ml, and limit of detection values of 0.048 and 0.032 μg/ml, for the fluorometric and the RRS methods, respectively. Moreover, the quenching between the dye and naftidrofuryl was studied using Stern-Volmer analysis, and the methodologies were experimentally optimized and validated. Additionally, acceptable recoveries were achieved when the procedures were applied to determine naftidrofuryl in pharmaceutical samples.

Synthesis and characterization of phenothiazine sensor for spectrophotometric and fluorescence detection of cyanide

A sensitive and selective phenothiazine-based sensor (PTZ) has been successfully synthesized. The sensor PTZ displayed specific identification of CN^- 'turn-off' fluorescence responses with a quick reaction and strong reversibility in an acetonitrile:water (90:10, V/V) solution. The sensor PTZ for detecting CN^- exhibits the marked advantages of quenching the fluorescence intensity, fast response time (60 s), and low value of the detection limit. The concentration that is authorized for drinking water by the WHO (1.9 μM) is far higher than the detection limit, which was found to be 9.11 × 10^-9 . The sensor displays distinct colorimetric and spectrofluorometric detection for CN^- anion due to the addition of CN^- anion to the electron-deficient vinyl group of PTZ, which reduces intramolecular charge transfer efficiencies. The 1:2 binding mechanism of PTZ with CN^- was validated by fluorescence titration, Job's plot, HRMS, ¹ H NMR, FTIR analysis, and density functional theory (DFT) investigations, among other methods. Additionally, the PTZ sensor was successfully used to precisely and accurately detect cyanide anions in actual water samples.

Utility of a xanthene-based dye for determination of nilotinib using two spectroscopic approaches. Applications to bulk powder, capsules, and spiked human plasma

Novel, selective, facile, and precise spectroscopic approaches were validated to determine nilotinib hydrochloride, a tyrosine kinase inhibitor used to treat patients with chronic myeloid leukemia. These approaches depend on the reaction of the tertiary amine group of nilotinib with erythrosine B in the Britton-Robinson buffer at pH 4. Method I, depends on measuring the absorbance of the formed complex at 551 nm. The absorbance concentration plot showed linearity over the concentration range of 1.0 to 9.0 μg/ml. Method II, involved the measurement of the quenching of the native fluorescence of erythrosine B by adding nilotinib in an acidic medium. The fluorescence quenching of erythrosine B was measured at 549 nm after excitation at 528 nm. This approach showed excellent linearity in the concentration range of 0.04 to 0.7 μg/ml. The limit of detection values for Method I and Method II were 0.225 and 0.008 μg/ml, respectively, while the limit of quantitation values for Method I and Method II were 0.68 and 0.026 μg/ml, respectively. To get the optimal conditions, factors that may affect the formation of the ion-pairing complex were thoroughly examined. The two approaches were carefully validated following the International Conference of Harmonization (ICH Q2R1) guidelines. Statistical assessment of the results achieved using the suggested and previously published comparison approaches showed no significant difference. The approaches were successful in determining nilotinib in a pharmaceutical dosage form as well as spiked human plasma samples. The eco-friendly properties of the methods were evaluated by three different tools.

Detection of Indigo Carmine dye in juices via application of photoluminescent europium-doped carbon dots from tannic acid

Indigo Carmine is a hazardous dye and produces an allergic action for humans despite the excessive use of the dye in several industrial fields. A sensitive and simple fluorescent assay for determining Indigo Carmine relying on quenching of the fluorescent europium-doped carbon dots by the action of inner filter effect was developed. This sensing platform involved the preparation of europium-doped carbon dots from the hydrothermal carbonization of tannic acid and europium chloride, which was used as fluorescent reagent with a distinctive excitation/emission wavelength at 307/340 nm. Both excitation and emission fluorescence of prepared carbon dots can be successfully quenched by adding Indigo Carmine dye. The developed spectrofluorimetric method exhibits good linearity with the concentration of Indigo Carmine dye in the range of 1.5 to 10.0 μg/ml and provided a limit of detection (LOD) value of 0.40 μg/ml. Furthermore, the prepared carbon nanoparticles were identified and characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), and ultraviolet (UV)-spectrophotometer techniques. In addition, the developed detecting approach was applied to determine Indigo Carmine in juice samples with acceptable recovery.

Resonance Rayleigh scattering approach based on association complex formation with erythrosine B for determination of venlafaxine, Application to the dosage form and spiked human plasma

The interaction of Venlafaxine Hydrochloride (VLX) with Erythrosine B was investigated by resonance Rayleigh scattering (RRS) spectroscopic technique. In acetate buffer (pH 3.4), erythrosine B reacted with VLX to form 1:1 ion pair complex with concomitant enhancement in RRS intensity which was measured at 330 nm. In addition, the stability constant and the change in free energy of the reaction were estimated. Based on this interaction a new method was developed for the sensitive VLX analysis using Erythrosine B as a probe. The results indicated that this method had a good selectivity in the presence of coexisting compounds. The scattering intensity (ΔI_RRS ) was linearly depended on VLX concentration over the range of 0.04-1.0 μg mL^-1 with determination coefficient (r) of 0.9998. The detection (LOD) and quantitation limits (LOQ) were 0.01 and 0.03 μg mL^-1 , respectively. This method could be suitably employed to the VLX analysis in pharmaceutical capsules and human plasma.

PVP-coated silver nanocubes as RRS probe for sensitive determination of Haloperidol in real samples

Polyol synthesis of silver nanocubes (Ag NCs) under dark conditions yielded nanoparticles with high uniformity and purity, as well as edge lengths of 42 nm with good stability and scattering cross-section. These nanoparticles were characterized by SEM, TEM, and Uv-vis spectroscopy. The presence of polyvinylpyrrolidone (PVP) as a capping agent on the surface of Ag NCs, as well as its satisfactory interaction level with Haloperidol (Hp) as an antipsychotic drug, has led to the use of these nanoparticles as Resonance RayleighScattering (RRS) probe to measure Hp. Indeed, Hp resulted in reducing the RRS signal of Ag NCs, and this change in RRS intensity was linear in the range of 10.0 to 800.0 µg L^-1 of Hp. The limits of detection (LOD) and quantification (LOQ) were found to be 1.5 and 5.0 µg L^-1, respectively. The influence of interfering species was studied, and it was found that the suggested method has good selectivity and can be used to monitor Hp in actual samples. As a result, this RRS probe operated well in determining Hp in pharmaceutical and human plasma samples with satisfactory recovery.

Catalytic oxidation of O-phenylenediamine by silver nanoparticles for resonance Rayleigh scattering detection of mercury (II) in water samples

In this study, a facile nanoparticle catalytic sensor for resonance Rayleigh scattering quantification of mercury (II) ion was developed. The developed approach is relied on the selective inhibition of the peroxidase-like activity of polyvinylpyrrolidone-stabilized silver nanoparticles (PVP-Ag-NPs) by mercury (II) ions. The synthesized PVP-Ag-NPs oxidize the aqueous solution of O-Phenylenediamine (colorless) to 2,3-phenazinediamine (bright yellow) and their resonance Rayleigh scattering (RRS) activity was completely suppressed. When mercury (II) was introduced, the RRS activity of PVP-Ag-NPs was turned on combined with a reduction of the intensity of the yellow color. The enhancement in the RRS intensity was related to the concentration of mercury (II) in the linear range of 10-2000 nM. The smaller size (4.5 nm), the large surface area and the uniform size (PDI = 0.379) of the synthesized PVP-Ag-NPs offered a higher chance for interaction between mercury (II) and PVP-Ag-NPs with the advantages of high sensitivity (LOD = 4 nM) and excellent selectivity for mercury (II) detection over several metals and anions.

Micellar sensitized Resonance Rayleigh Scattering and spectrofluorometric methods based on isoindole formation for determination of Eflornithine in cream and biological samples

α-Difluoromethylornithine or Eflornithine is an FDA-approved drug used for the treatment of Sleeping Sickness (as vials dosage form) and also used for diminishing the unwanted excess facial hair in the hirsutism (as creams dosage form). The proposed work is based on the condensation interaction between the amino moiety of Eflornithine and O-phthalaldehyde/2-mercaptoethanol to form a highly fluorescent isoindole derivative. The fluorescence and the Resonance Rayleigh Scattering (RRS) intensities of the reaction product were greatly augmented upon the addition of hexadecyl-trimethyl ammonium bromide by 153% and 250%, respectively. After optimization of the reaction conditions, the formed isoindole derivative was measured fluorometrically at λ_emission= 429 nm after λ_excitation= 337 nm. Moreover, the significant augmentation in the RRS intensity of the formed product was measured at λ_max= 422 nm. In regards to accuracy, sensitivity, robustness and precision, the proposed methods were validated according to ICH guidelines. Furthermore, the proposed methods were successfully applied for the assay of Eflornithine in various commercial brands of the pharmaceutical cream samples with good recovery. In addition to the current fluorometric method was confirmed to be effective in the assaying of Eflornithine in spiked plasma and urine specimens with good recovery.

Applying different spectroscopic techniques for the selective determination of daclatasvir using merbromin as a probe: Applications on pharmaceutical analysis

In this study, rapid resonance Rayleigh scattering (RRS), spectrophotometric, and spectrofluorimetric methods were performed for facile quantitation of daclatasvir dihydrochloride without interference from sofosbuvir (a co-formulated anti-hepatitis C virus drug). The proposed approaches were based on forming a binary complex between daclatasvir dihydrochloride and merbromin reagent at pH 4.1. The binary complex was measured spectrophotometrically at λ_max = 544 nm. The spectrofluorimetric approach relied on the quenching effect of daclatasvir dihydrochloride on the fluorescence strength of merbromin at λ_Emission = 545 nm. The RRS approach depended on augmentation in the merbromin RRS spectrum at 363 nm upon addition of daclatasvir dihydrochloride. The presented methodologies were linear over the concentration ranges 2.5-15.0, 0.2-1.6 and 0.15-3.0 μg ml^-1 with detection limits of 0.45, 0.046, and 0.036 μg ml^-1 for the spectrophotometric approach, the spectrofluorometric approach, and RRS approach, respectively. Current approaches were validated in compliance with International Council for Harmonisation guidelines and utilized practically to estimate daclatasvir dihydrochloride either in binary mixtures with sofosbuvir or in its commercial tablet dosage form with good results. Moreover, the test for content uniformity was applied successfully on commercial tablets using the current spectroscopic approaches.

Application of Hantzsch reaction for sensitive determination of eflornithine in cream, plasma and urine samples

Eflornithine (EFN) is an anti-Trypanosoma brucei agent for the medication of sleeping sickness and widely distributed for the treatment of hirsutism (unwanted facial hair in women). The presented work demonstrates a comprehensive analytical approach for the spectrofluorometric determination of EFN in commercial cream samples and various biological samples. The proposed method is based on the formation of a highly yellow-green fluorescence dihydropyridine derivative after the interaction between EFN and acetylacetone/formaldehyde reagent in a slightly acidic medium. Furthermore, the optimal variables such as reagent volumes, pH of the medium, heating time, buffer volume, heating temperature and diluting solvent were carefully selected to achieve the maximum fluorescence activity. The fluorescence activity for the formed derivative was measured at λ emission = 477 nm after λ excitation = 418 nm. Concerning linearity, accuracy, sensitivity, precision and robustness, the presented method was validated and verified according to ICH guidelines. Moreover, the proposed work offered a selective determination for EFN in various brands of pharmaceutical cream without any interference from excipients. Eventually, the current approach was assured to be successful in the estimation of EFN in urine and plasma samples with acceptable recovery results.

Utility of 4-chloro-7-nitrobenzofurazan for spectrofluorimetric and spectrophotometric determinations of the anti-hirsutism agent (α-difluoromethylornithine) in pharmaceutical cream samples

α-Difluoromethylornithine is an effective medication for the treatment of African Trypanosomiasis and widely distributed for the treatment of hirsutism. This work provides an adequate analytical protocol for the spectrophotometric and the spectrofluorimetric determination of α-difluoromethylornithine through its interaction with 4-chloro-7-nitrobenzofurazan (NBD-chloride) reagent. After optimization of the reaction conditions (NBD-chloride volume, buffer volume, the best diluting solvent, heating time and temperature and pH of the medium) the reaction product was measured spectrophotometrically at λ_max = 478 nm and spectrofluorimetrically at λ_emission = 540 nm after λ_excitation = 475 nm. The proposed methods were linear over the ranges 5-30 μg ml^-1 and 0.4-2 μg ml^-1 for the spectrophotometric method and the spectrofluorimetric method, respectively. Moreover, the proposed work offers an adequate sensitive and selective determination for α-difluoromethylornithine where the detection limits were 0.90 μg ml^-1 and 0.071 μg ml^-1 for the spectrophotometric method and the spectrofluorimetric method, respectively. Furthermore, both methods were successfully applied for the quantification of α-difluoromethylornithine in the pharmaceutical cream samples with acceptable recovery results.