A comparative study of validated spectrophotometric and TLC- spectrodensitometric methods for the determination of sodium cromoglicate and fluorometholone in ophthalmic solution

An integrated framework to develop an efficient valid green (EVG) HPLC method for the assessment of antimicrobial pollutants with potential threats to human health in aquatic systems

The persistence of antimicrobial drugs in aquatic environments has raised critical concerns about their possible impact on drinkable water quality and human health. The Nile River is experiencing water pollution owing to increasing discharges of highly contaminated home and industrial effluents and inadequate water management systems. Investigations of the presence of three antimicrobial agents, ciprofloxacin (CIP), sulfamethoxazole (SMZ), and albendazole (ALB), in the Egyptian aquatic system are recommended using a chromatographic method because of their reported existence in the African aquatic environment. In this study, an integrated framework, Efficient Valid Green (EVG), for analytical techniques is proposed and displayed via its radar chart. The EVG framework is achieved through three main pillars: efficiency, validation, and greenness. The proposed EVG-HPLC method was developed and optimized using the AQbD methodology via a face-centered composite (FCC) design by identifying the proper critical method parameters (CMPs) that influence critical quality attributes (CQAs). The method was fully validated according to ICH guidelines, including a factorial robustness study within concentration ranges of 1-100 μg mL-1, 2-100 μg mL-1, and 10-100 μg mL-1 for CIP, SMZ, and ALB, respectively. The proposed method was evaluated in terms of greenness using AGREE (score 0.55) and ComplexGAPI metrics. The optimized chromatographic conditions included a C18 column and a mobile phase of water : acetonitrile : methanol in a ratio of 60 : 19 : 21, v/v/v, respectively, with an aqueous solution of pH 3.5 adjusted with phosphoric acid at a flow rate of 1.57 mL min-1 at 285 nm. The raw water samples collected from Nile River freshwater at different locations were treated using Oasis® PRiME HLB cartridges with satisfactory recoveries for the three analytes (>90%), and the three drugs were detected using the proposed EVG-HPLC method.

UV spectrophotometric methods for simultaneous determination of ketorolac tromethamine and olopatadine hydrochloride: Application of multiple standard addition for assay of ophthalmic solution

Ophthalmic preparations that contain ketorolac tromethamine (KET) and olopatadine HCl (OLO) are used to relieve seasonal allergies and allergic conjunctivitis. Simultaneous quantification of KET and OLO was held by validated and simple spectrophotometric methods. KET was determined directly from the fundamental UV absorption spectra (at 323 nm), while OLO was determined after performing either dual wavelength or ratio derivative methods. The first method was based on measuring the absorbance difference (ΔA) between 243 and 291 nm, while the second depended on generating first derivative ratio spectra using 3.0 µg/mL KET as a divisor and measuring OLO responses at 234 nm (minima). Multiple standard addition method was applied to enable the determination of OLO which is considered as the weakly absorbing species as well as the minor component in a challenging dosage form ratio (4:1). The linearity ranges of the developed methods were 3-12 μg/mL and 4-40 μg/mL for KET and OLO, respectively. Simultaneous determination of both drugs was successfully implemented to lab prepared eye drops that contain KET, OLO and benzalkonium chloride as an inactive ingredient. Greenness assessment indicates minimal impact on environment. The developed methods determined the cited drugs with % recovery ± SD of 99.63 ± 0.01 for KET, 100.90 ± 0.02 and 100.31 ± 0.01 for OLO using dual wavelength and first derivative ratio methods, respectively. Using F-test and t-test at confidence level %95 to compare between the results of the presented methods and a reported method show no significant difference which allows precise, accurate, rapid, and simple quantification of quality control samples that contain KET and OLO.

Enhanced fluorimetric detection of diphenylpyraline HCl using micelle and cyclodextrin mediated approach: Spectrofluorimetric and micellar liquid chromatographic application for either single or combined formulation with caffeine and paracetamol

Highly sensitive micellar spectrofluorimetric method (Method I) has been developed and validated for the determination of diphenylpyraline HCl in pharmaceutical tablets and in plasma. Sodium dodecyl sulfate improves the intensity of fluorescence of diphenylpyraline at 286 nm at pH 5 that allow its determination in plasma at nano-level. the mean percent recovery ± S.D was 99.719 ± 0.338 in plasma. In addition, Green cyclodextrin-modified micellar liquid chromatographic method (Method II) has been developed and validated for simultaneous determination of diphenylpyraline, paracetamol and caffeine using cyclodextrin micellar mobile phase consisted of 30 mM Brij*35, 0.5 mM hydroxypropyl β-cyclodextrin and phosphate buffer pH 4: MeOH (95:5, %v/v) that allows their simultaneous determination with enhanced spectrofluorimetric detection of diphenylpyraline. Method II was effectively applied for the simultaneous determination of diphenylpyraline, paracetamol and caffeine in a ternary laboratory prepared mixture which contained all possible excipients with mean percent recoveries ± S.D of 100.176 ± 1.008, 101.166 ± 0.415 and 100.708 ± 1.836, respectively. Linearity range for Method I was 0.1-1 μg. mL^-1 for diphenylpyraline and for Method II was 0.3-50, 25-350, and 0.5-50 for caffeine, paracetamol and diphenylpyraline, respectively. Method I was also applied in spiked human plasma with linearity range 0.2-0.5 μg. mL^-1. The methods are verified to have excellent greenness.

Selective spectrofluorimetric determination of two corticosteroids along with their co-formulated drugs and degradation products in ophthalmic solution and aqueous humour

Prednisolone acetate (PNO) and fluorometholone (FRT) are corticosteroids, co-formulated with moxifloxacin HCl (MFX) and cromolyn sodium (CML), respectively. PNO has a negligible quantum yield and its hydrolytic degradation products have enhanced fluorescence, which is 250-fold greater. FRT is a nonfluorescent drug, but its hydrolytic degradation products show reasonable fluorescence; MFX and CML have native fluorescence. Two methods were proposed based on the determination of PNO and FRT via their hydrolytic degradation products in the presence of other degradation products. Method (A) was developed for simultaneous determination of PNO and MFX in the presence of PNO degradation products by measuring peak amplitudes of the first derivative (¹ D) of its enhanced fluorescence; PNO and MFX were measured at 345 and 473 nm, respectively. Method (B) is a synchronous fluorescence spectroscopic method for simultaneous determination of FRT and its co-formulated drug CML in the presence of its degradation products. Fluorescence intensities were measured at λ_em 283 and 347 nm for FRT and CML, respectively, using Δλ = 99.20 nm. Validation of the proposed methods was conducted as per International Council for Harmonisation (ICH) guidelines. The proposed methods were successfully applied for the determination of the proposed drugs in bulk powder, ophthalmic solution, and rabbit's aqueous humour.

Micelle-enhanced spectrofluorimetric determination of diphenhydramine: application to human plasma and its simultaneous determination with naproxen in pharmaceutical tablets

Two simple and sensitive spectrofluorimetric methods were developed and validated for determination of diphenhydramine. The use of sodium dodecyl sulfate surfactant at pH 7 enhances the fluorescence intensity of diphenhydramine at 286 nm (method I) enabling its nanodetermination in biological samples with mean per cent recovery ± SD of 100.33 ± 1.519. Method I was validated according to ICH-Q2R1 guidelines and was successfully applied for determination of diphenhydramine in pharmaceutical dosage form and spiked human plasma in the concentration ranges 0.1-4.0 μg/mL and 0.2-1.0 μg/mL, respectively. Method I acted as a basis for the development of a first derivative synchronous spectrofluorimetry (method II) for simultaneous analysis of diphenhydramine and naproxen using a zero-crossing approach. Method II determines both drugs with linearity ranges of 0.05-3.0 μg/mL and 0.1-0.9 μg/mL for diphenhydramine and naproxen, respectively. The developed method was applied for the simultaneous determination of both drugs in their laboratory-prepared mixtures containing all expected excipients. Method II determines both drugs with a mean percent recovery ± SD of 100.56 ± 0.891 and 100.20 ± 1.125 for diphenhydramine and naproxen, respectively. The method was statistically compared with a reported method using Student's t- and F- tests, and no significant differences were observed.

Development of Advanced Chemometric-Assisted Spectrophotometric Methods for the Determination of Cromolyn Sodium and Its Alkaline Degradation Products

Advanced and sensitive spectrophotometric and chemometric analytical methods were successfully established for the stability-indicating assay of cromolyn sodium (CS) and its alkaline degradation products (Deg1 and Deg2). Spectrophotometric mean centering ratio spectra method (MCR) and chemometric methods, including principal component regression (PCR) and partial least square (PLS-2) methods, were applied. Peak amplitudes after MCR at 367.8 nm, 373.8 nm and 310.6 nm were used within linear concentration ranges of 2-40 µg mL^-1, 5-40 µg mL^-1 and 10-100 µg mL^-1 for CS, Deg1 and Deg2, respectively. For PCR and PLS-2 models, a calibration set of eighteen mixtures and a validation set of seven mixtures were built for the simultaneous determination of CS, Deg1 and Deg2 in the ranges of 5-13 µg mL^-1, 8-16 µg mL^-1, and 10-30 µg mL^-1, respectively. The authors emphasize the importance of a stability-indicating strategy for the investigation of pharmaceutical products.

Advanced approaches for the treatment and amplification of weak spectral signals produced by critical concentrations in white multicomponent systems

An analytical investigation was carried out to study the treatment and amplification of the spectral signals produced by critical concentrations with high accuracy and precision using two advanced approaches. The factorized-spectrum approach was applied through two novel methods which were: absorptivity centering technique via both: factorized zero order absorption spectrum (ACT-FSD⁰_ΔA) and factorized ratio spectrum (ACT-FSR_ΔP). The proposed methods were found to be linear in the ranges of (15-100 μg/mL) and (3-40 μg/mL) for ASP and MTO, respectively. Those methods were compared to the methods following the geometrical standard addition approach: ratio H-point standard addition method (RHPSAM) and geometrical induced amplitude modulation (GIAM). The approaches were applied for the determination of the minor component metoclopramide in its mixture with the major component aspirin in the challengeable ratio of (1,90) respectively in a white multicomponent system. The results obtained from the proposed approaches were statistically compared with each other. The methods were validated according to ICH guidelines where the results were found to be within the acceptable limits. The methods were found to be accurate and reliable for the determination of metoclopramide critical concentration besides aspirin concentration. The results of single factor ANOVA analysis indicated that there is no significant difference among the developed methods. These methods provided simple resolution of this binary combination from synthetic mixtures and pharmaceutical preparation and can be conveniently adopted for routine quality control analysis.

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.

Application of 19F NMR Spectroscopy for Content Determination of Fluorinated Pharmaceuticals

A simple, rapid, and selective quantitative nuclear magnetic resonance spectroscopic method was evaluated for the determination of the content of fluorinated pharmaceuticals. ¹⁹F NMR spectra were either obtained in dimethylsulfoxide-d₆ or aqueous buffer, using trifluoroacetic acid as internal standard. Quantification of 13 fluorine-containing pharmaceuticals spanning various pharmacological classes was accomplished using the proposed method. The method was found to be fit for purpose (interday precision 1.2% relative standard deviation) and may thus be applied for routine analysis and quality control of fluorine-containing pharmaceuticals due to its simplicity, nondestructive sample measurement, reliability, and high specificity. Therefore, ¹⁹F NMR may serve as a suitable analytical tool for the identification and selective determination of fluorinated pharmaceuticals used as reference materials and bulk samples.

Stability-Indicating RP-HPLC Methods for the Determination of Fluorometholone in Its Mixtures with Sodium Cromoglycate and Tetrahydrozoline Hydrochloride

Two stability-indicating reversed-phase liquid chromatographic methods were developed and validated for the determination of fluorometholone (FLU) in its mixtures with sodium cromoglycate (SCG) and tetrahydrozoline hydrochloride (THZ). The first HPLC method (Method 1) was based on isocratic elution of FLU and SCG along with their alkaline degradation products on a reversed phase C18 column (250 × 4.6 mm id)-ACE Generix 5, using a mobile phase consisting of methanol-water (70 : 30, v/v), pH adjusted to 2.5 using orthophosphoric acid at a flow rate of 1.2 mL min(-1) Quantitation was achieved with UV detection at 240 nm. The second HPLC method (Method 2) was based on isocratic elution of FLU, its alkaline degradation product and THZ on a reversed phase C8 column (250 × 4.6 mm)-ACE Generix 5, using a mobile phase consisting of acetonitrile-50 mM potassium dihydrogen orthophosphate (40 : 60, v/v) at a flow rate of 2 mL min(-1) Quantitation was achieved by applying dual-wavelength detection, where FLU and its alkaline degradation product were detected at 240 nm and THZ was detected at 215 nm at ambient temperatures. Linearity, accuracy and precision were found to be acceptable over the concentration range of 5-50 and 10-500 μg mL(-1) for FLU and SCG (Method 1) and over the concentration range of 5-80 and 5-60 μg mL(-1) for FLU and THZ (Method 2), respectively. Besides, the FLU alkaline degradation product was verified using IR, NMR and LC-MS spectroscopy. The two proposed methods could be successfully applied for the routine analysis of the studied drugs either in their pure bulk powders or in their pharmaceutical preparations without any preliminary separation step.

Computation of geometric representation of novel spectrophotometric methods used for the analysis of minor components in pharmaceutical preparations

Novel spectrophotometric methods were applied for the determination of the minor component tetryzoline HCl (TZH) in its ternary mixture with ofloxacin (OFX) and prednisolone acetate (PA) in the ratio of (1:5:7.5), and in its binary mixture with sodium cromoglicate (SCG) in the ratio of (1:80). The novel spectrophotometric methods determined the minor component (TZH) successfully in the two selected mixtures by computing the geometrical relationship of either standard addition or subtraction. The novel spectrophotometric methods are: geometrical amplitude modulation (GAM), geometrical induced amplitude modulation (GIAM), ratio H-point standard addition method (RHPSAM) and compensated area under the curve (CAUC). The proposed methods were successfully applied for the determination of the minor component TZH below its concentration range. The methods were validated as per ICH guidelines where accuracy, repeatability, inter-day precision and robustness were found to be within the acceptable limits. The results obtained from the proposed methods were statistically compared with official ones where no significant difference was observed. No difference was observed between the obtained results when compared to the reported HPLC method, which proved that the developed methods could be alternative to HPLC techniques in quality control laboratories.

Novel spectrophotometric methods for simultaneous determination of Amlodipine, Valsartan and Hydrochlorothiazide in their ternary mixture

This work represents a comparative study of two smart spectrophotometric techniques namely; successive resolution and progressive resolution for the simultaneous determination of ternary mixtures of Amlodipine (AML), Hydrochlorothiazide (HCT) and Valsartan (VAL) without prior separation steps. These techniques consist of several consecutive steps utilizing zero and/or ratio and/or derivative spectra. By applying successive spectrum subtraction coupled with constant multiplication method, the proposed drugs were obtained in their zero order absorption spectra and determined at their maxima 237.6 nm, 270.5 nm and 250 nm for AML, HCT and VAL, respectively; while by applying successive derivative subtraction they were obtained in their first derivative spectra and determined at P230.8-246, P261.4-278.2, P233.7-246.8 for AML, HCT and VAL respectively. While in the progressive resolution, the concentrations of the components were determined progressively from the same zero order absorption spectrum using absorbance subtraction coupled with absorptivity factor methods or from the same ratio spectrum using only one divisor via amplitude modulation method can be used for the determination of ternary mixtures using only one divisor where the concentrations of the components are determined progressively. The proposed methods were checked using laboratory-prepared mixtures and were successfully applied for the analysis of pharmaceutical formulation containing the cited drugs. Moreover comparative study between spectrum addition technique as a novel enrichment technique and a well established one namely spiking technique was adopted for the analysis of pharmaceutical formulations containing low concentration of AML. The methods were validated as per ICH guidelines where accuracy, precision and specificity were found to be within their acceptable limits. The results obtained from the proposed methods were statistically compared with the reported one where no significant difference was observed.

A comparative study of different aspects of manipulating ratio spectra applied for ternary mixtures: derivative spectrophotometry versus wavelet transform

This work represents a comparative study of different aspects of manipulating ratio spectra, which are: double divisor ratio spectra derivative (DR-DD), area under curve of derivative ratio (DR-AUC) and its novel approach, namely area under the curve correction method (AUCCM) applied for overlapped spectra; successive derivative of ratio spectra (SDR) and continuous wavelet transform (CWT) methods. The proposed methods represent different aspects of manipulating ratio spectra of the ternary mixture of Ofloxacin (OFX), Prednisolone acetate (PA) and Tetryzoline HCl (TZH) combined in eye drops in the presence of benzalkonium chloride as a preservative. 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, limitation 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.

A comparative study of smart spectrophotometric methods for simultaneous determination of sitagliptin phosphate and metformin hydrochloride in their binary mixture

Simple, specific, accurate and precise spectrophotometric methods were developed and validated for the simultaneous determination of the oral antidiabetic drugs; sitagliptin phosphate (STG) and metformin hydrochloride (MET) in combined pharmaceutical formulations. Three methods were manipulating ratio spectra namely; ratio difference (RD), ratio subtraction (RS) and a novel approach of induced amplitude modulation (IAM) methods. The first two methods were used for determination of STG, while MET was directly determined by measuring its absorbance at λmax 232 nm. However, (IAM) was used for the simultaneous determination of both drugs. Moreover, another three methods were developed based on derivative spectroscopy followed by mathematical manipulation steps namely; amplitude factor (P-factor), amplitude subtraction (AS) and modified amplitude subtraction (MAS). In addition, in this work the novel sample enrichment technique named spectrum addition was adopted. The proposed spectrophotometric methods did not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined. The selectivity of the developed methods was investigated by analyzing laboratory prepared mixtures of the drugs and their combined pharmaceutical formulations. Standard deviation values were less than 1.5 in the assay of raw materials and tablets. The obtained results were statistically compared to that of a reported spectrophotometric method. The statistical comparison showed that there was no significant difference between the proposed methods and the reported one regarding both accuracy and precision.

A comparative study of novel spectrophotometric methods based on isosbestic points; application on a pharmaceutical ternary mixture

This work represents the application of the isosbestic points present in different absorption spectra. Three novel spectrophotometric methods were developed, the first method is the absorption subtraction method (AS) utilizing the isosbestic point in zero-order absorption spectra; the second method is the amplitude modulation method (AM) utilizing the isosbestic point in ratio spectra; and third method is the amplitude summation method (A-Sum) utilizing the isosbestic point in derivative spectra. The three methods were applied for the analysis of the ternary mixture of chloramphenicol (CHL), dexamethasone sodium phosphate (DXM) and tetryzoline hydrochloride (TZH) in eye drops in the presence of benzalkonium chloride as a preservative. The components at the isosbestic point were determined using the corresponding unified regression equation at this point with no need for a complementary method. The obtained results were statistically compared to each other and to that of the developed PLS model. The specificity of the developed methods was investigated by analyzing laboratory prepared mixtures and the combined dosage form. The methods were validated as per ICH guidelines where accuracy, repeatability, inter-day precision and robustness were found to be within the acceptable limits. The results obtained from the proposed methods were statistically compared with official ones where no significant difference was observed.