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.

Derivatization-free conventional and synchronous spectrofluorimetric estimation of atenolol and amlodipine

Fixed-dose combinations for treatment of hypertension are observed in many dosages in the global market because of their high efficacy compared to single component dosage forms. One of these effective combinations is atenolol/amlodipine which is usually administered to patients with hypertension. Hence, development of facile, accurate, and sensitive methods for simultaneous estimation of atenolol and amlodipine is of great importance for quality control testing and pharmacokinetic studies. In our study, we developed two spectrofluorimetric methods to estimate both compounds in different pharmaceuticals. The first method is based on the estimation of atenolol and amlodipine by double-scan conventional spectrofluorimetry where the fluorescence intensities of atenolol and amlodipine were measured at 299 and 434 nm after excitation at 274 and 358 nm, respectively. The second method depends on synchronous spectrofluorimetric measurements at Δλ = 70 nm, where atenolol is assayed at 266 nm and amlodipine is assayed at 363 nm. Methods' optimizations were carried out to select the optimum conditions that render high selectivity and sensitivity. Such optimizations included assessment of solvents, surfactants, buffer volumes and pHs. The conventional spectrofluorimetric method was rectilinear over concentration range of 30.0-300.0 ng mL-1 for atenolol and 0.25-7.00 µg mL-1 for amlodipine while the synchronous spectrofluorimetric method showed linearity over the ranges of 0.60-6.00 µg mL-1 for atenolol and 0.25-7.00 µg mL-1 for amlodipine with low detection limits (≤0.12 µg mL-1) for both compounds in the two methods. It is the first work that demonstrates estimation of atenolol and amlodipine in their combinations by conventional and synchronous spectrofluorimetry. Both methods were applied to estimate atenolol and amlodipine in different pharmaceuticals with high %recovery and low %RSD.

Advances in miniaturized nanosensing platforms for analysis of pathogenic bacteria and viruses

Pathogenic bacteria and viruses are the main causes of infectious diseases all over the world. Early diagnosis of such infectious diseases is a critical step in management of their spread and treatment of the infection in its early stages. Therefore, the innovation of smart sensing platforms for point-of-care diagnosis of life-threatening infectious diseases such as COVID-19 is a prerequisite to isolate the patients and provide them with suitable treatment strategies. The developed diagnostic sensors should be highly sensitive, specific, ultrafast, portable, cheap, label-free, and selective. In recent years, different nanosensors have been developed for the detection of bacterial and viral pathogens. We focus here on label-free miniaturized nanosensing platforms that were efficiently applied for pathogenic detection in biological matrices. Such devices include nanopore sensors and nanostructure-integrated lab-on-a-chip sensors that are characterized by portability, simplicity, cost-effectiveness, and ultrafast analysis because they avoid the time-consuming sample preparation steps. Furthermore, nanopore-based sensors could afford single-molecule counting of viruses in biological specimens, yielding high-sensitivity and high-accuracy detection. Moreover, non-invasive nanosensors that are capable of detecting volatile organic compounds emitted from the diseased organ to the skin, urine, or exhaled breath were also reviewed. The merits and applications of all these nanosensors for analysis of pathogenic bacteria and viruses in biological matrices will be discussed in detail, emphasizing the importance of artificial intelligence in advancing specific nanosensors.

Acriflavine: an efficient green fluorescent probe for sensitive analysis of aceclofenac in pharmaceutical formulations

Acriflavine is a multipurpose drug that shows antibacterial, antiviral, antimalarial, and antifungal activities. The remarkable native fluorescence of acriflavine is exploited in analytical chemistry field as an efficient probe for analysis of pharmaceutical and biological compounds. The fluorescent probe action of acriflavine is based on the remarkable fluorescence turning-off via formation of ion-pair complexes with acidic drugs at a specific pH. Herein, the acidic drug aceclofenac is analysed for the first time using acriflavine as a fluorescent probe. Aceclofenac can form an ion-pair complex with acriflavine at pH 8.5, and hence it partially turns off the fluorescence intensity of acriflavine over a concentration range of 1-20 µg/mL. The fluorescence quenching was monitored at 502 nm following an excitation at 265 or 451 nm. The reaction stoichiometry between acriflavine and aceclofenac was found to be 1:1 using limiting logarithmic method. The type of quenching was confirmed to be static using Stern-Volmer plot. The method showed low values of quantitation limit (0.89 µg/mL) and detection limit (0.29 µg/mL). Moreover, the method was linear (r = 0.9999), accurate, precise (RSD < 1.7%), robust, and specific. The proposed method was successfully employed to analyse aceclofenac in its dosage forms with high %recovery (98-101%). Additionally, GAPI and AGREE approaches were used to guarantee the suggested techniques' greenness, and the findings showed an excellent level of greenness.

Adjusted green spectrophotometric determination of favipiravir and remdesivir in pharmaceutical form and spiked human plasma sample using different chemometric supported models

The environmentally friendly design of analytical methods is gaining interest in pharmaceutical analysis to reduce hazardous environmental impacts and improve safety and health conditions for analysts. The adaptation and integration of chemometrics in the development of environmentally friendly analytical methods is strongly recommended in the hope of promising benefits. Favipiravir and remdesivir have been included in the COVID-19 treatment guidelines panel of several countries. The main objective of this work is to develop green, tuned spectrophotometric methods based on chemometric based models for the determination of favipiravir and remdesivir in spiked human plasma. The UV absorption spectra of favipiravir and remdesivir has shown overlap to some extent, making simultaneous determination difficult. Three advanced chemometric models, classical least squares, principal component regression, and partial least squares, have been developed to provide resolution and spectrophotometric determination of the drugs under study. A five-level, two-factor experimental design has been used to create the described models. The spectrally recorded data of favipiravir and remdesivir has been reviewed. The noise region has been neglected as it has a negative impact on the significant data. On the other hand, the other spectral data provided relevant information about the investigated drugs. A comprehensive evaluation and interpretation of the results of the described models and a statistical comparison with accepted values have been considered. The proposed models have been successfully applied to the spectrophotometric determination of favipiravir and remdesivir in pharmaceutical form spiked human plasma. In addition, the environmental friendliness of the described models was evaluated using the analytical eco-scale, the green analytical procedure index and the AGREE evaluation method. The results showed the compliance of the described models with the environmental characteristics.

Label-free green estimation of atenolol and ivabradine hydrochloride in pharmaceutical and biological matrices by synchronous spectrofluorimetry

In this work, a label-free, rapid, and sensitive synchronous spectrofluorometric method was implemented to assay atenolol (ATL) and ivabradine hydrochloride (IVB) in pharmaceutical and biological matrices. Simultaneous determination of ATL and IVB by conventional spectrofluorometry cannot be implemented because of the clear overlap of the emmision spectra of ATL and IVB. To overcome this problem, synchronous fluorescence measurements at a constant wavelength difference (Δλ) combined with mathematical derivatization of the zero order spectra were perforemed. The results indicated a good resolution between emission spectra of the studied drugs when the first-order derivative of the synchronous fluorescence scans at Δλ = 40 nm was conducted using ethanol as the optimum solvent which is less hazardous than other organic solvents such as methanol and acetonitrile, keeping the method safe and green. The amplitudes of the first derivative synchronous fluorescent scans of ATL and IVB in ethanol were monitored at 286 and 270 nm to simultaneously estimate ATL and IVB, respectively. Method optimisation was conducted by assessing different solvents, buffer pHs, and surfactants. The optimum results were obtained when ethanol was utilized as a solvent without using any other additives. The developed method was linear over concentration ranges of 10.0-250.0 ng mL^-1 for IVB and 100.0-800.0 ng mL^-1 for ATL with detection limits of 3.07 and 26.49 ng mL^-1 for IVB and ATL, respectively. The method was utilized to assay the studied drugs in their dosages and in human urine samples with acceptable % recoveries and RSD values. The greenness of the method was implemented by three approaches involving the recently reported metric (AGREE) which ensured the eco-freindship and safety of the method.

Eco-friendly spectrophotometric methods for determination of remdesivir and favipiravir; the recently approved antivirals for COVID-19 treatment

Remdesivir (REM) and Favipiravir (FAV) are recently approved antivirals prescribed in severely ill COVID-19 patients. Therefore, development of new, simple, rapid, sensitive, and selective methods for analysis of such drugs in their pharmaceutical formulations will be highly advantageous. Herein, we have developed different spectrophotometric methods for analysis of the studied analytes. Method I is based on direct spectrophotometric analysis of REM and FAV in ethanol at λ_max 244 and 323 nm, respectively. For simultaneous quantitation of REM and FAV, methods II-V were followed. Method II is based on derivative spectrophotometry in which REM was determined in second-order derivative spectra at 248 nm (the zero-crossing wavelength for FAV), while FAV was measured in first-order derivative spectra at 337 nm (the zero-crossing point for REM). Method III is the dual-wavelength method in which spectral intensities were subtracted at 244-207 nm for REM and at 330-400 nm for FAV. Method IV is the ratio subtraction in which ratio spectra were obtained by a suitable divisor followed by subtraction of intensities at 272-340 nm and 335-222 nm for REM and FAV, respectively. Method V is the derivative ratio method in which the obtained ratio spectra in method IV were converted to first-order derivative and then REM and FAV were recorded at 280 and 340 nm, respectively. Calibration graphs were linear in the ranges of 1-10 µg/mL for REM through all methods and 1-20 µg/mL for FAV in methods I and II, and 2-20 µg/mL by the other methods. The evolved methods were applied to pharmaceutical dosage forms of REM and FAV. All the proposed methods were further applied to human plasma samples containing both drugs with acceptable mean recoveries.

Enhanced Luminol Chemiluminescence with Oxidase-like Properties of FeOOH Nanorods for the Sensitive Detection of Uric Acid

FeOOH nanorods, as one-dimensional nanomaterials, have been widely used in many fields due to their stable properties, low cost, and easy synthesis, but their application in the field of chemiluminescence (CL) is rarely reported. In this work, FeOOH nanorods were synthesized by a simple and environmentally friendly one-pot hydrothermal method and used for the first time as a catalyst for generating strong CL with luminol without additional oxidant. Remarkably, luminol-FeOOH exhibits about 250 times stronger CL than the luminol-H₂O₂ system. Its CL intensity was significantly quenched by uric acid. We established a simple, rapid, sensitive, and selective CL method for the detection of uric acid with a linear range of 20-1000 nM and a detection limit of 6.3 nM (S/N = 3). In addition, we successfully applied this method to the detection of uric acid in human serum, and the standard recoveries were 95.6-106.4%.

Recent advances in microchip electrophoresis for analysis of pathogenic bacteria and viruses

Life-threatening diseases, such as hepatitis B, pneumonia, tuberculosis, and COVID-19, are widespread due to pathogenic bacteria and viruses. Therefore, the development of highly sensitive, rapid, portable, cost-effective, and selective methods for the analysis of such microorganisms is a great challenge. Microchip electrophoresis (ME) has been widely used in recent years for the analysis of bacterial and viral pathogens in biological and environmental samples owing to its portability, simplicity, cost-effectiveness, and rapid analysis. However, microbial enrichment and purification are critical steps for accurate and sensitive analysis of pathogenic bacteria and viruses in complex matrices. Therefore, we first discussed the advances in the sample preparation technologies associated with the accurate analysis of such microorganisms, especially the on-chip microfluidic-based sample preparations such as dielectrophoresis and microfluidic membrane filtration. Thereafter, we focused on the recent advances in the lab-on-a-chip electrophoretic analysis of pathogenic bacteria and viruses in different complex matrices. As the microbial analysis is mainly based on the analysis of nucleic acid of the microorganism, the integration of nucleic acid-based amplification techniques such as polymerase chain reaction (PCR), quantitative PCR, and multiplex PCR with ME will result in an accurate and sensitive analysis of microbial pathogens. Such analyses are very important for the point-of-care diagnosis of various infectious diseases.

Conventional and synchronous spectrofluorometric determination of the recently administered drugs for treatment of COVID-19 favipiravir and apixaban

COVID-19 is a fast-spreading pandemic that is caused by SARS-CoV-2 viral pathogen. Combination therapy of the antiviral favipiravir and the anticoagulant apixaban is one of the efficient treatment regimens. Therefore, development of novel and sensitive methods for simultaneous analysis of such combination is highly advantageous. Herein, two eco-friendly, simple, rapid, and cost-effective spectrofluorometric methods were evolved for the estimation of favipiravir and apixaban in pharmaceutical and biological matrices. Method I was based on analysis of favipiravir and apixaban by the first-order derivative of the conventional fluorescence spectra obtained after excitation at 300 nm, where favipiravir and apixaban were detected at 468.8 and 432.0 nm, respectively. Method II relied on dual scan synchronous spectrofluorometry, in which favipiravir was determined at 364 nm using Δλ = 60 nm while apixaban was analyzed at 274 nm using Δλ = 200 nm. Method optimization was performed for selecting the optimum conditions at which maximum sensitivity and selectivity were obtained. This report is the first one that describes simultaneous analysis of favipiravir and apixaban by synchronous spectrofluorometry. The developed methods were successfully applied to evaluate favipiravir and apixaban in spiked human plasma and in pharmaceutical dosages with high %recoveries and low RSD.

Development of lucigenin-N-hydroxyphthalimide chemiluminescence system and its application to sensitive detection of Co2

N-hydroxyphthalimide (NHPI) is an efficient organic catalyst and an important chemical raw material which can be used as an intermediate in organic synthesis of drugs and pesticides. In this study, NHPI has been used as a coreactant of lucigenin chemiluminescence (CL) for the first time. The CL of the developed system is significantly enhanced in the presence of Co²⁺. Therefore, we developed a novel lucigenin-NHPI CL method coupled with flow injection analysis for the sensitive, precise, and selective determination of Co²⁺. The linear range of this method is 1-1000 nM, and the detection limit is 67 pM (S/N = 3). In addition, this method has a good selectivity for Co²⁺. It has been applied to the detection of Co²⁺ in lake water, and the standard recovery rate is 95.9-103.2%, indicating that the method is feasible.

First derivative synchronous spectrofluorimetric analysis of bisoprolol fumarate and ivabradine in pharmaceutical and biological matrices. Investigation of the method greenness

A novel, facile, rapid, and precise synchronous spectrofluorimetric method was evolved for the simultaneous estimation of bisoprolol fumarate and ivabradine in dosage forms and biological fluids. The estimation is based on measuring the first derivative of the synchronous fluorescence spectra of ivabradine and bisoprolol fumarate in ethanol at Δλ = 80nm. The peak amplitudes are measured at 234.4 nm (zero-crossing point of ivabradine) and 244.0 nm (zero-crossing point of bisoprolol fumarate) to simultaneously analyse bisoprolol fumarate and ivabradine, respectively. The spectrofluorimetric method was optimized by investigating different solvent systems, pH values, and surfactants. The proposed method was linear over concentration ranges of 30.0-200.0 ng/mL and 30.0-180.0 ng/mL for ivabradine and bisoprolol fumarate, respectively with detection limits of 4.88 and 5.28 ng/ml. The developed method was employed for individual assay of the studied compounds in their pharmaceutical dosage forms with high %recoveries. Moreover, the method was applied to analyse ivabradine and bisoprolol fumarate in spiked human urine with %recoveries of 99.98±1.16 and 99.95±1.96 for ivabradine and bisoprolol fumarate, respectively. The method greenness was also investigated by Analytical GREEnness (AGREE), Analytical Eco-Scale, and Green Analytical Procedure Index (GAPI) metrics, which ensured the eco-friendship of the proposed method.

A synchronous spectrofluorometric technique for simultaneous detection of alfuzosin and tadalafil: applied to tablets and spiked biological samples

A facile, accurate, eco-friendly and sensitive spectrofluorometric method was evolved to assay alfuzosin hydrochloride (AFH) and tadalafil (TDF) in different matrices. Such a co-administered combination is clinically used for the treatment of lower urinary tract symptoms. Both compounds are characterized by their native fluorescence spectra upon excitation at specific wavelengths. Their characteristic fluorescence spectra were used for sensitive assay of the studied analytes in tablets and human biological samples. The assay principle is based on first-order synchronous spectrofluorometric scan using Δλ = 60 nm in which AFH peaks were recorded at 366 nm. Meanwhile, TDF measurements were recorded at 293 nm in the same scans without overlap with AFH spectra. Recent analytical chemistry trends were implemented to lessen occupational and environmental perils, using ethanol as a diluting solvent for method optimization and application. Linearity ranges were 5.0-90.0 and 10.0-100.0 ng ml^-1 for AFH and TDF, respectively in their raw materials with average % recoveries of 100.44% and 99.73% in raw materials, 100.15% and 100.20% in spiked plasma, and 97.14% and 99.99% in spiked urine. The proposed method was successfully applied to Prostetrol and Starkoprex commercial tablets with no interference with common tablet additives.

A synchronous spectrofluorometric technique for simultaneous detection of alfuzosin and tadalafil: applied to tablets and spiked biological samples

A facile, accurate, eco-friendly and sensitive spectrofluorometric method was evolved to assay alfuzosin hydrochloride (AFH) and tadalafil (TDF) in different matrices. Such a co-administered combination is clinically used for the treatment of lower urinary tract symptoms. Both compounds are characterized by their native fluorescence spectra upon excitation at specific wavelengths. Their characteristic fluorescence spectra were used for sensitive assay of the studied analytes in tablets and human biological samples. The assay principle is based on first-order synchronous spectrofluorometric scan using Δλ = 60 nm in which AFH peaks were recorded at 366 nm. Meanwhile, TDF measurements were recorded at 293 nm in the same scans without overlap with AFH spectra. Recent analytical chemistry trends were implemented to lessen occupational and environmental perils, using ethanol as a diluting solvent for method optimization and application. Linearity ranges were 5.0-90.0 and 10.0-100.0 ng ml^-1 for AFH and TDF, respectively in their raw materials with average % recoveries of 100.44% and 99.73% in raw materials, 100.15% and 100.20% in spiked plasma, and 97.14% and 99.99% in spiked urine. The proposed method was successfully applied to Prostetrol and Starkoprex commercial tablets with no interference with common tablet additives.

Highly Sensitive Detection of the Insecticide Azamethiphos by Tris(2,2'-bipyridine)ruthenium(II) Electrogenerated Chemiluminescence

Azamethiphos (AZA) is an insecticide and neurotoxic agent that causes the inhibition of acetylcholinesterase (AChE). AChE is a vital enzyme for neurotransmission because it metabolizes acetylcholine neurotransmitter at the synaptic cleft and terminates synaptic transmission. It is worth mentioning that organophosphates and carbamates inhibit AChE. These AChE inhibitors bind to the active site of the enzyme and inactivate it, leading to paralysis and death. Herein, for the first time, we develop a sensitive, low-cost, and rapid electrogenerated chemiluminescence (ECL) system for the detection of AZA. The designed ECL sensor was applied for the highly sensitive detection of AZA with a wide dynamic range (from 0.1 μM to 1000 μM) and low detection limit of 0.07 μM (S/N = 3). The practical utility of the sensor demonstrates high recoveries (96-102%) in real samples of lake water and wastewater.

Dimeric G-Quadruplex: An Efficient Probe for Ultrasensitive Fluorescence Detection of Mustard Compounds

Some mustard compounds (mustards) are highly toxic chemical warfare agents. Some are explored as new anticancer drugs. Therefore, the fast, selective, and sensitive detection of mustards is extremely important for public security and cancer therapy. Mustards mostly target the N7 position on the guanine bases of DNA. The guanine-rich G-quadruplex DNA (G4) has been widely studied in the sensing area, and it was found that dimeric G4 (D-G4) could dramatically light up the fluorescence intensity of thioflavin T (ThT). Based on this, we used for the first time the D-G4 DNA as a selective probe for ultrasensitive fluorescence detection of nitrogen mustard (NM). When NM occupies the N7 on guanine, it can block the formation of the D-G4 structure due to the steric hindrance, and hence, it inhibits the combination of D-G4 with ThT, leading to a sharp decrease of fluorescence intensity. The proposed reaction mechanism is proved using ultraviolet-visible (UV-Vis) spectra, circular dichroism (CD) spectra, and polyacrylamide gel electrophoresis. Herein, the concentration of D-G4/ThT used is as low as 50 nM due to its highly fluorescent performance, enabling both high sensitivity and low cost. NM can be detected with a wide linear range from 10 to 2000 nM. The detection limit of NM reaches a surprisingly low concentration of 6 nM, which is 2 or 3 orders of magnitude lower than that of previously developed fluorescence methods for mustards and simulants.

First-order derivative synchronous spectrofluorimetric determination of two antihypertensive drugs, metolazone and valsartan, in pharmaceutical and biological matrices

In this study, a facile, rapid, and sensitive spectrofluorimetric method was evolved to analyse two antihypertensive drugs, namely, metolazone (MTZ) and valsartan (VST), in pharmaceutical and biological matrices. Both analytes exhibited intrinsic fluorescence activities which were significantly affected by environmental factors such as pH and solvent systems. However, simultaneous determination of MTZ and VST by conventional spectrofluorometry cannot be achieved simply because of the strong overlap between their fluorescence spectra. Thus, a combination of derivative and synchronous spectrofluorometry was conducted to overcome this dilemma. The proposed method relies on measurement of the first-order derivative of synchronous fluorescence intensity of the studied drugs at Δλ = 160 nm using 0.1 M acetic acid as the optimum solvent. The amplitudes of the first derivative synchronous fluorescence spectra of MTZ and VST were recorded at 236.0 nm (zero-crossing point of VST) and at 262.8 nm (zero-crossing point of MTZ) for simultaneous analysis of MTZ and VST, respectively. The fluorescent method was optimized efficiently to get the maximum selectivity and sensitivity by investigating different solvents, different buffer pHs, and different surfactants. The highest sensitivity and selectivity were achieved when 0.1 M acetic acid was used as a solvent. The method showed a linear concentration range of 10.0-100.0 ng mL^-1 and a limit of detection of <3.0 ng mL^-1 for each analyte. Statistical data analysis confirmed that no significant difference between the proposed spectrofluorometric method and the reference methods. The validity of the proposed spectrofluorometric method approved its suitability for quality control work. The proposed spectrofluorometric method was applied to assay the studied drugs in pharmaceutical dosage and in biological matrices with acceptable %recoveries and small RSD values.

Utilization of a micellar matrix for simultaneous spectrofluorimetric estimation of alfuzosin hydrochloride and vardenafil hydrochloride

A sensitive and direct spectrofluorimetric method was developed for simultaneous quantitation of two co-administered drugs, namely, alfuzosin hydrochloride (AFH) and vardenafil hydrochloride (VRH). Both drugs exhibited native fluorescence properties that could be exploited to assay them in biological fluids with high sensitivity. Spectrofluorimetric analysis of AFH and VRH is based on excitation of both drugs at 265 nm where emission spectra were recorded separately for AFH and VRH at 380 and 485 nm, respectively. Micellar trends in analytical chemistry were adopted to minimize both environmental and occupational hazards, using distilled water and sodium dodecyl sulphate (serves as a micellar medium that enhanced the sensitivity of AFH and VRH) for analysis of both drugs in their raw materials, tablets, and human biological fluids (plasma and urine). Linearity ranges were 1.0-16.0 and 10.0-700.0 ng mL^-1 for AFH and VRH, respectively. The proposed method was successfully assessed for analysis of AFH and VRH in spiked human plasma and urine samples over the following concentrations: 1.0-12.0 ng mL^-1 and 4.0-400.0 ng mL^-1 for both drugs, simultaneously with mean recoveries of 101.08 % and 102.06 % in plasma and 96.75 % and 92.8 % in urine. Statistical analysis of the practical results has proved quite good agreement and revealed there were no significant differences in the accuracy and precision with those obtained by the comparison methods. The proposed method was applied successfully to Prostetrol® and Powerecta® commercial tablets without interference with tablet additives.

Development of three ecological spectroscopic methods for analysis of betrixaban either alone or in mixture with lercanidipine: greenness assessment

Three eco-friendly spectrophotometric methods were developed for determination of the novel anticoagulant drug, betrixaban (BTX). The first method (method A) was based on direct analysis of BTX at 229.4 nm on the zero-order spectrum using methanol as the optimum solvent. While the second method (method B) was based on measuring difference absorption value (ΔA) of BTX at 335 nm, which was obtained from pH-induced spectral difference (difference spectra of BTX in 0.1 M NaOH versus 0.1 M HCl). The third method (method C) was based on measurement of the first-derivative amplitudes of BTX and its co-administered Ca channel blocker lercanidipine (LER) at 304 and 229 nm for simultaneous assay of BTX and LER, respectively. All methods were linear over concentration ranges of 1.0-20.0 and 8.0-80.0 µg ml^-1 for BTX in methods A and B, respectively, and of 1.0-20.0 and 1.0-25.0 µg ml^-1 for BTX and LER, respectively, in method C. The three methods were fully validated and assessed for greenness by three metrics: analytical eco-scale, green analytical procedure index and Analytical GREEnness metrics. The results indicated the validity and greenness of the proposed methods. Moreover, the methods were applied to assay the studied analytes in their dosage forms with high percentage of recovery and low percentage of relative s.d. values.

Simultaneous determination of ergotamine, caffeine and dipyrone in their ternary mixture by applying double divisor and first derivative ratio spectra methods

Two validated methods namely, double divisor ratio spectra derivative spectroscopy and derivative ratio spectroscopy with zero crossing point were applied to assay a ternary mixture of ergotamine tartrate (EGT), caffeine (CAF) and dipyrone sodium (DIP) without any additional separation steps. The linearity ranges using both methods were (1.0 µg/mL-70.0 µg/mL), (60.0 µg/mL - 100.0 µg/mL) and (100.0 µg/mL - 300.0 µg/mL) for EGT, CAF and DIP respectively. Double divisor ratio spectroscopy (method A) depends on dividing the different peak responses of EGT on (summation of peaks responses of CAF and DIP each of 10.0 µg/mL concentration) at λ max=342 nm, 310 nm and 315 nm for EGT, CAF and DIP respectively. Derivative ratio spectroscopy with zero crossing point (method B) depends on dividing the peak responses of two drugs (EGT and CAF) on (10.0 µg/mL of DIP) and dividing the peak response of DIP on peak response of (10.0 µg/mL of EGT). The detection limits of the studied drugs applying method A were (3.54, 12.96 and 8.748 µg/mL), with quantitation limits of (10.73, 39.28 and 26.51 µg/mL) for EGT, CAF and DIP respectively. Regarding method B, the limits of detection and quantitation for EGT were 0.604 µg/mL and 1.829 µg/mL respectively: with corresponding values of 19.44 µg/mL and 58.92 µg/mL for CAF and 20.44 µg/mL and 61.9 µg/mL for DIP. The obtained results were compared to those obtained by published methods and were found to be in accordance.

Single-Electrode Electrochemical System for the Visual and High-Throughput Electrochemiluminescence Immunoassay

The electrochemiluminescence (ECL) immunoassay with its visual and high-throughput detection has received considerable attention in the past decade. However, the development of a facile and cost-effective ECL device is still a great challenge. Herein, a single-electrode electrochemical system (SEES) for the visual and high-throughput ECL immunoassay was developed. The SEES was designed by attaching a plastic sticker with multiple holes onto a single carbon ink screen-printed electrode based on a resistance-induced potential difference. Due to its excellent properties of adsorption and bioaffinity, the carbon ink screen-printed electrode is applied to immobilize antibodies. When cardiac troponin I (cTnI), a specific biomarker of acute myocardial infarction, is present, it will be captured by the immobilized cTnI antibodies on the electrode surface, inhibiting electron transfer, resulting in a decrease of the ECL intensity of the luminol-H₂O₂ system. Using a smartphone as the detector, cTnI could be determined, ranging from 1 to 1000 ng mL^-1, with a detection limit of 0.94 ng mL^-1. The SEES based on the carbon ink screen-printed electrode is characterized by its high simplicity, cost effectiveness, and user-friendliness compared with conventional three-electrode systems and bipolar electrochemical systems using electrode arrays and shows superior advantages over other immunoassay strategies, with the elimination of multistep assembling and labeling processes. What is more, the fabricated SEES holds great potential in the point-of-care testing due to its tiny size and the combination of a smartphone detector.

Optimization and Validation of a Facile RP-HPLC Method for Determination of Betrixaban and Lercanidipine in Pharmaceutical and Biological Matrices

A simple, accurate, rapid and sensitive reversed-phase high-performance liquid chromatography (RP-HPLC) method was established for determination of a novel non-vitamin K antagonist oral anticoagulant drug, betrixaban, and its co-administered calcium-channel blocker drug, lercanidipine, in pharmaceutical formulations and biological fluids. The proposed HPLC method was the first chromatographic method applied to estimate this mixture in a short chromatographic run (<6 min), high resolution between betrixaban/lercanidipine (Rs = 7.12) and acceptable values of limit of detection (LOD), limit of quantification (LOQ) and percentage of relative standard deviation (%RSD). The chromatographic separation was performed on a cyano column using a mobile phase composed of acetonitrile:methanol:water (35:35:30, v/v/v) containing 0.2% orthophosphoric acid adjusted to pH 3.2 by triethylamine, programmed with a flow rate of 1 mL/min with UV detection at 240 nm. The proposed method showed linearity over the concentration ranges of (0.20-20.0 μg/mL) and (0.25-25.0 μg/mL) for betrixaban and lercanidipine, respectively. All validation parameters met the acceptance criteria according to ICH guidelines in terms of linearity, LOD, LOQ, accuracy, precision, robustness, specificity and system suitability. The method was applied to assay the studied analytes in their pharmaceutical formulations with high % recovery (98-102%) and low %RSD (<1.5). Furthermore, the proposed method was successfully applied for the determination of betrixaban in spiked human plasma.

Quantitative proton nuclear magnetic resonance method for simultaneous analysis of fluticasone propionate and azelastine hydrochloride in nasal spray formulation

A facile, rapid, accurate and selective quantitative proton nuclear magnetic resonance (¹H-qNMR) method was developed for the simultaneous determination of fluticasone propionate (FLP) and azelastine hydrochloride (AZH) in pharmaceutical nasal spray for the first time. The ¹H-qNMR analysis of the studied analytes was performed using inositol as the internal standard and dimethyl sulfoxide-d₆ (DMSO-d₆) as the solvent. The quantitative selective proton signal of FLP was doublet of doublet at 6.290, 6.294, 6.316 and 6.319 ppm, while that of AZH was doublet at 8.292 and 8.310 ppm. The internal standard (inositol) produced a doublet signal at 3.70 and 3.71 ppm. The method was rectilinear over the concentration ranges of 0.25-20.0 and 0.2-15.0 mg ml^-1 for FLP and AZH, respectively. No labelling or pretreatment steps were required for NMR analysis of the studied analytes. The proposed ¹H-qNMR method was validated efficiently according to the International Council on Harmonisation guidelines in terms of linearity, limit of detection, limit of quantification, accuracy, precision, specificity and stability. Moreover, the method was applied to assay the analytes in their combined nasal spray formulation. The results ensured the linearity (r ² > 0.999), precision (% RSD < 1.5), stability, specificity and selectivity of the developed method.

Simultaneous spectrophotometric quantitative analysis of elbasvir and grazoprevir using assisted chemometric models

Artificial neural networks and genetic algorithm artificial neural networks, chemometric assisted spectrophotometric models, were developed for the quantitative analysis of elbasvir and grazoprevir in their newly FDA approved pharmaceutical dosage form. The UV absorption spectra of elbasvir and grazoprevir show severe degree of overlap which caused difficulty for selecting certain spectrophotometric method with advantage of simultaneous quantitative analysis of the cited drugs. After extensive study and many experimental trials, artificial neural networks and genetic algorithm artificial neural networks were the suitable models for the quantitative analysis of studied drugs in their binary mixture. Experimental design and constructing the calibration and validation sets of the binary mixture were achieved to implement the proposed models. The models were optimized with the aid of five-levels, two factors experimental design. The designed models were successfully applied to the quantitative analysis of Zepatier® tablets. The results were statistically compared with another reported HPLC quantitative analytical method with no significant difference by applying Student t-test and variance ratio F-test.

Simultaneous spectrophotometric quantitative analysis of velpatasvir and sofosbuvir in recently approved FDA pharmaceutical preparation using artificial neural networks and genetic algorithm artificial neural networks

Two chemometric assisted spectrophotometric models were applied for the quantitative analysis of velpatasvir and sofosbuvir in their newly FDA approved pharmaceutical dosage form. The UV absorption spectra of velpatasvir and sofosbuvir showed certain degree of overlap which exhibited degree of difficulty for the choice of certain method provides simultaneous quantitative analysis of the cited drugs. Artificial neural networks and genetic algorithm artificial neural networks were the suitable model for the quantitative analysis of velpatasvir and sofosbuvir in their binary mixture. Experimental design and building the calibration set for the binary mixture were achieved to implement the described models. The proposed models were optimized with the aid of five-levels, two factors experimental design. Spectral region of 380-400 nm was rejected which resulted in 181 variables. GA reduced absorbance matrix to 72 and 36 variables for velpatasvir and sofosbuvir respectively. The models succeeded to estimate the studied drugs with acceptable values of root mean square error of calibration and root mean square error of prediction. The developed models were successfully applied to the quantitative analysis of the two drugs in Epclusa® tablets. The results were statistically compared with another published quantitative analytical method with no significant difference by applying Student t-test and variance ratio F-test.

Determination of three antiepileptic drugs in pharmaceutical formulations using microfluidic chips coupled with light-emitting diode induced fluorescence detection

In this study, a facile, sensitive, and precise lab-on-a-chip electrophoretic method coupled with light-emitting diode induced fluorescence (LED-IF) detection was developed to assay three antiepileptic drugs, namely, vigabatrin, pregabalin, and gabapentin, in pharmaceutical formulations. The analytes were derivatised offline for the first time with fluorescine-5-isothiocyanate (FITC) to yield highly fluorescent derivatives with λ_ex/em of 490/520nm. The FITC-labelled analytes were injected, separated, and quantitated by a microfluidic electrophoresis device using fluorescence detection. The labelled analytes were monitored using a blue LED-IF system. The separation conditions were significantly optimised adding specific concentrations of heptakis-(2,6-di-O-methyl)-β-cyclodextrin (HDM-β-CD) and methylcellulose to the buffer solution (40mM borate buffer). HDM-β-CD acted as a selective host for the studied antiepileptic drugs, rendering a high separation efficiency. Methylcellulose was used as an efficient dynamic coating polymer to prevent the labelled drugs from being adsorbed on the inner surfaces of the poly (methylmethacrylate) microchannels. A laboratory-prepared ternary mixture of the three antiepileptic drugs was separated within 100s with acceptable resolution between all the three analytes (R_s>3) and a high number of theoretical plates (N) for each analyte (N≈10⁶ plates/m). The sensitivity of the method was enhanced approximately 80-fold by stacking to yield a detection limit below 0.6ngmL^-1 in the concentration range of 2.0-200.0ngmL^-1. The method was successfully validated for analysing the studied drugs in their pharmaceutical formulations.

Analysis of clozapine in its tablets using two novel spectrophotometric reactions targeting its tertiary amino group

Two simple spectrophotometric methodologies have been proposed and validated for the measurement of an atypical antipsychotic drug Clozapine (CLZ). Method A depends on interaction of CLZ with N-bromosuccinimide(NBS) resulting in formation of a yellowish orange colored product, measured at 320 nm. The linearity range was 5.0-70.0 μg/mL. Method B depends on condensation of the same drug with acetic acid mixed anhydride reagent producing a purple colored product, measured at 319 nm. The linearity range was 8.0-24.0 μg/mL. All parameters affecting the reaction condition (volume of both reagent, temperature, time and the different diluting solvents) were optimized. Both methods were successfully applied to assay CLZ in its pure form and tablets giving mean percentage recoveries of (98.87 ± 1.8 and 100 ± 1.7) for method A, and corresponding values of (98.6 ± 0.96 and 99.5 ± 1) for method B. Besides, the study of reactions stoichiometry was performed and the reaction mechanisms were proposed.

Determination of baclofen and vigabatrin by microchip electrophoresis with fluorescence detection: application of field-enhanced sample stacking and dynamic pH junction

A novel microchip gel electrophoretic method for the assay of baclofen and vigabatrin for the first time.

Determination of six anti-Parkinson drugs using cyclodextrin-capillary electrophoresis method: application to pharmaceutical dosage forms

Addition of β-cyclodextrin to the background electrolyte improves the separation efficiency of multi-component mixtures through inclusion complex formation.

Hepatitis-B virus and schistosomiasis infections in childhood proteinuria

Hepatitis-B surface antigen (HBsAg), circulating anti-schistosomal IgG (CSAb) and circulating specific schistosomal immune complexes (CIC) were detected, using ELISA, in sera of 40 active nephrotic children, 40 active S. mansoni infected cases and 20 apparently normal age-matched controls. The presence of HBsAg cases was significantly higher among nephrotic cases (20%), active S. mansoni cases (17.5%) than controls. Moreover, HBsAg cases were significantly higher in positive CIC S. mansoni cases than negative CIC ones. The mean O.D. readings of CSAb was significantly higher in positive HBsAg nephrotic cases than negatives. At the same time, the anti-schistosomal antibodies were higher in S. mansoni cases with proteinuria than those without. Specific CIC level was significantly higher among nephrotic and schistosomiasis cases than controls. The CIC were significantly higher in schistosomiasis cases with positive HBsAg than those with negative HBsAg and were detected in 80% of cases with proteinuria compared to 37% of cases without proteinuria with a statistically significant difference. On the other hand, CIC level was not influenced, in nephrotic cases, by the presence or absence of HBsAg. It was concluded that the presence of proteinuria was considered as a good monitor of the kidney affection either with schistosomiasis or the nephrotic syndrome or the HBsAg. The detection of CIC can be used as a good monitor too and could be included in methods of early diagnosis and/or following the disease prognosis.