Nm For Method Research Articles

Investigation of facile spectroscopic approaches for rapid calycosin determination in invitro biological samples and pharmaceuticals; application to the content uniformity of capsules

Calycosin, the major bioactive isoflavonoid inAstragali Radix and an important anti-viral drug with a variety of pharmacological actions, is being determined by five different spectroscopic methods. Two spectrophotometric methods have been investigated including measuring the absorption spectra at λmax = 270 nm and the first derivative spectra at λ = 288 nm for methods I and II, respectively. For the first time; the native fluorescence of calycosin is measured without adding any reagents. The fluorescence intensity was measured at 340 nm after excitation at 282 nm in method III. The fourth method involves the direct measuring of a first derivative spectrofluorimetric emission peak at 292 nm. In method V synchronous fluorescence spectra were recorded in methanol at Δλ = 70 nm. The linear range for the fluorescence-based methods was 0.05–1.0 µg/mL and for the UV-based methods was 0.5–10.0 µg/mL. The methods were validated per International Council of Harmonization (ICHQ2R1) guidelines. The limits of detection were found to be down to 0.11 and 0.12 µg/mL for the spectrophotometric methods, and 15.0, 18.0,16.0 ng/ mL, for the spectrofluorimetric approaches respectively, representing the high sensitivity. Accordingly, this permitted the quantitation of calycosin in spiked human plasma samples with satisfactory percentage recoveries (94.50.–102.50 %). The methods were utilized for calycosin analysis in different matrices including plasma and capsules with high precision and accuracy.

Simultaneous Estimation of Nebivolol Hydrochloride and Hydrochlorothiazide in Tablets

A method was established for simultaneous valuation of Nebivolol hydrochloride (NBH) and Hydrochlorothiazide (HYT) from the tablet dosage form by partial simultaneous equation method, the method was found to be sensitive and accurate. The maxima of both the drugs were noted in 0.1 N hydrochloric acid. The NBH has lambda maxima at 283 nm and HYT at 270 and 320 nm. As NBH shows no absorbances at 320nm. So effective wavelengths designated were 283 nm and 270 nm for Method I, 283 nm, and 320 nm for

Development and Validation of Direct Spectrophotometric Method for the Estimation of Glimepiride

Aims: To develop simple, sensitive and direct spectrophotometric methods for the estimation of widely prescribed antidiabetic hypoglycemic agent Glimepiride in pure and pharmaceutical dosage form.
 Place and duration of study: Research Centre of Taywade Group of Institution Koradi, Nagpur affiliated to Rashtrasant Tukadoji Maharaj Nagpur University Nagpur between June 2020 and March 2021.
 Methodology: Two spectrophotometric methods were developed based on ion-pair formation of drug with Cresol Red dye (Method A) and Bromophenol Blue dye (Method B) in methanol and chloroform. The possible reaction mechanism was proposed with evaluation of statistical parameters. The methods were validated for its application to determine Glimepiride in bulk as well as in pharmaceutical formulations
 Results: The Beer's law was found linear in the range 10 - 60 µgml-1 at 450 nm for method A and 2 - 20 µgml-1 at 578 nm for method B, respectively. The linear regression equation obtained by applying least square regression analysis for Glimepiride were found to be Absorbance = 0.0136 x Concentration in µgml-1 + 0.028; R2 = 0.9965 for method A and Absorbance = 0.0428x Concentration in µgml-1 +0.0722; R2 = 0.9949 for method B. The Sandell's sensitivity was found to be 0.0696 and 0.0177 for method A and B respectively. The apparent molar absorptivity calculated to be for both methods were 6.6724 x103 and 2.0999 x104 l mol-1 cm-1.
 Conclusion: Two direct spectrophotometric methods for determination of Glimepiride have been developed successfully and validated for sensitivity, accuracy, precision, repeatability and robustness as per ICH guidelines. The developed methods are suitable for the routine estimation of Glimepiride in pure and dosage form.

Determination of Meloxicam Using Direct and Indirect Flow Injection Spectrophotometry

Background: Meloxicam is a non-steroidal anti-inflammatory drug, known to inhibit cyclooxygenase, a key enzyme of prostaglandin biosynthesis at the site of inflammation. Objectives: Two sensitive and fast spectrophotometric methods (direct and indirect) using flOW INJection Analysis (FIA) have been described for the assay of meloxicam in pure and in pharmaceutical formulations. Methods: The direct method (method A) depended on the coupling of meloxicam with diazotized procaine benzylpenicillin in alkaline medium. In contrast, the indirect method (method B) involved a charge transfer reaction between the alkaline hydrolytic product of meloxicam as n-donor with metol (p-methylaminophenol sulfate) as a π- acceptor using sodium periodate as an oxidant. Results: The colored products exhibited absorption maxima at 492 and 656 nm for method A and B respectively. The methods obeyed Beer’s low over concentration ranges of 5-80 and 15-225 μg/mL, respectively. The detection limits were 2.73 and 5.26 μg/mL for direct and indirect methods, respectively. The chemical and physical parameters associated with FIA manifolds were optimized to construct the most sensitive and reproducible results. Conclusion: Methods described herein are cheap, environmentally friendly and showed no significant difference with those of the official method indicated no significant difference in accuracy and precision.

SPECTROPHOTOMETRIC DETERMINATION OF ATORVASTATIN CALCIUM AND PITAVASTATIN CALCIUM THROUGH ION-PAIR COMPLEX FORMATION USING ACID DYES IN PHARMACEUTICAL FORMULATIONS AND HUMAN URINE SAMPLES

Objective: The main objective was to develop simple, cost-effective, rapid and selective spectrophotometric methods for the determination of atorvastatin calcium and pitavastatin calcium in pure and pharmaceutical formulations using acid dyes like bromothymol blue, bromocresol purple and bromocresol green and also in human urine samples.
 Methods: The developed methods were based on the formation of ion-pair complexes between statin drugs and acid dyes after studying the optimization conditions. The association constants of the developed ion-pair complexes were evaluated using Benesi–Hildebrand equation. The methods were validated according to ICH guidelines.
 Results: The formed ion-pair complexes showed maximum absorbance which was measured at 637 nm for both methods A and D, 601 nm, 606 nm for methods B and E and 631 nm for both methods C and F respectively with correlation coefficients 0.999. The analytical parameters and their effects in the developed methods were investigated. The ion-pair complexes were stable up to 24 h and showed good linearity. The molar absorptivity, Sandell sensitivity, detection, and quantification limits were also calculated. The stoichiometry ratio in all the cases was 1:2 by using Job’s method of continuous variation. The recovery studies again showed good results because co-formulated substances did not interfere for the determination of ATC and PTC in the developed methods.
 Conclusion: The developed methods were applicable for routine quality control analysis of ATC and PTC in pure and pharmaceutical dosage forms. Good results were obtained when the developed methods were applied in healthy human urine samples.

Spectrophotometric Microdetermination of Alzheimer’s Drug Memantine HCl in Biological Samples

Three simple, rapid, accurate and precise methods are described for the determination of memantine hydrochloride (MEM) by oxidation with cerium (IV) sulphate. Method (A) is based on the oxidation of the drug by a known excess amount of cerium (IV) sulphate and the unreacted Ce4+ is treated with ammonium ferrous sulphate, and the iron (III) sulphate produced is complexed with thiocyanate and measured at 480 nm. The methods B and C involve the addition of excess Ce4+ and determination of the unreacted oxidant by decrease the red color of chromotrope 2R (C2R) at a suitable λmax 528 nm for method B or decrease the orange pink color of rhodamine 6G (Rh6G) at a suitable λmax 525 nm for method C. Different variables affecting the reaction between memantine HCl and Ce4+ were studied and optimized. The molar absorptivity and Sandell sensitivity of the procedure were calculated in addition to limits of detection and quantification. Excipients used as additives in pharmaceutical formulations did not interfere in the proposed procedures, which successfully applied to the determination of MEM in bulk drug forms, tablets and spiked human plasma.

Spectrophotometric determination of Mefenamic acid viadiazo coupling reaction using different reagents in dosage forms

Three simple, accurate and precise spectrophotometric methods were proposed for determining of mefenamic acid in pure form as well as in dosage forms. The proposed methods were based on the coupling of mefenamic acid with diazotized 4-aminohippuric acid, 4-nitroaniline and 4-aminoantipyrine in alkaline medium for methods A, B and C, respectively. The colored azo dyes were quantitated photometrically at 432, 453, and 406 nm for methods A, B and C, respectively. Different variables affecting the reactions were optimized. Beer’s law was obeyed over the concentration ranges of 0.5-20, 1.0-16 and 0.2-14 μg/ml for methods A, B, and C, respectively. The colored azo dyes remained stable for more than 3 hours in the three methods. The proposed methods were applied successfully to determine mefenamic acid in dosage forms.

Advanced Spectrophotometric Analysis of Sunset Yellow Dye E110 in Commercial Food Samples

Sunset Yellow E110 is one of the famous synthetic food dyes, which belongs to the family of azo dyes and widely used in food industry as additives and nutrient sources. Two highly sensitive and simple spectrophotometric methods are developed for determination of Sunset Yellow E110 in some commercial food samples. The first method is based on redox reaction of Sunset Yellow with copper (II) followed by complex formation. Results indicated the formation of 1:1 metal-dye complex at pH 9.0. The second one is based on its oxidation by alkaline KMnO4 to green manganate species. The two reactions are monitored spectrophotometrically at maximum absorbance 350 and 610 nm for methods I and II, respectively. Variables are carefully studied, and the conditions are optimized. Under the optimized experimental conditions, Beer’s Law was obeyed in the concentration ranges 9.05–67.87 and 13.57–72.38 μg ml−1 for the two methods, respectively. The apparent molar absorptivities, Sandell’s sensitivity, and detection and quantification limits are calculated. Matrix effects are also investigated. The proposed methods are successfully applied for the determination of Sunset Yellow dye in commercial food products. The concentration level of the dye is found to be within the safe recommended limits.

Oxidation and Complexation-Based Spectrophotometric Methods for Sensitive Determination of Tartrazine E102 in Some Commercial Food Samples

Two new sensitive spectrophotometric methods are reported for determination of tartrazine (Tz) (E102) in some commercial food samples. The first method involves two coupled reactions, the reduction of Cu(II) to Cu(I) by the analyte in acetate buffer medium (pH = 5.9) at 30°C and the complexation reaction between Cu(I) and Tz oxidized form to yield Cu-Tz complex (method I). The other method is based on oxidation of Tz by alkaline KMnO4. These reactions are monitored spectrophotometrically at maximum absorbances 332 and 610 nm for methods (I and II) respectively. Variables affecting these reactions are carefully studied and the conditions are optimized. The stability constants are calculated at 293, 303, 313 and 323 K. The thermodynamic parameters, Gibb’s free energy change (ΔG), entropy change (ΔS), and enthalpy change (ΔH) associated with the complexation reaction are calculated and discussed. Under optimized conditions the proposed methods (I, II) obey Beer’s law 10.69 - 85.50, 5.34 - 34.12 μg·ml-1 of Tz respectively. The molar absorptivity, sandel sensitivity, detection and quantification limits are calculated. Matrix effects are also investigated. The methods are successfully applied to the quantification of Tz in different commercially food samples. The results obtained are in good agreement with those obtained by the reported methods at the 95% confidence level.

Spectrophotometric determination and spectroscopic studies on Schiff base and charge transfer complex of ketorolac tromethamine

Ketorolac tromethamine is a versatile analgesic drug used extensively for the treatment of fever and moderate to severe pain. It is a potent non-steroidal anti-inflammatory drug that extends opioid-level analgesia to patients. Two new selective methods are proposed for spectrophotometric determination of ketorolac tromethamine (KT) in pure and pharmaceutical formulation. The determination procedures are based on the condensation reaction of KT with 2,4-dinitrophenylhydrazine (DNPH) in strongly alkaline medium resulting in the formation of red-colored hydrazones which is quantitated at 424 nm for method A and method B involves the charge transfer reaction between KT as electron donor and 7,7′,8,8′-tetracyanoquinodimethane (TCNQ) as π-acceptor to form dark green-colored complex which is measured at 842 nm. Linear correlation is obtained in the range 0.50–18.50 μg mL−1 and 2.00–50.00 μg mL−1 with detection limits of 0.1579 and 0.3721 μg mL−1 for method A and method B, respectively. The optimum analytical conditions are analyzed, and the proposed assay is validated as per the ICH guidelines. The developed methods are effectively applied to the determination of KT in tablets, injections, and ophthalmic formulations with good percentage recoveries. The final reaction products are characterized by spectral analysis (FT-IR and 1H NMR). In addition, the surface morphology of the reaction products are also studied using scanning electron microscopy.

Indirect Spectrophotometric Methods for the Determination of Tadalafil

Two spectrophotometric methods were developed for the determination Tadalafil in pharmaceutical preparations. The methods are based on the oxidation reaction with known excess amount of Ce(IV) and estimation of the unreacted amount using Indigo carmine dye (Method A) and in Methylene blue dye (Method B). the factors affecting the reaction conditions were studied and the absorbance of absorbance of the oxidation reaction products were monitored at 610 and 600 nm for methods A and B respectively. Beer's law is obeyed in the concentration ranges 11 to 50 and 10 to 55 ppm, the limits of detection and quantification are reported. The proposed method was applied to the determination of the drug in pharmaceutical formulations and the results demonstrated that the method is equally accurate, precise and reproducible as the official methods. The validity of method was established by recovery studies with satisfactory results.

Assay of Dexmedetomidine in Bulk Samples and Pharmaceutical Formulations by Extractive Spectrophotometry

Three simple and sensitive spectrophotometric methods (A-C) for the assay of dexmedetomidine in pure and dosage forms based on the formation of chloroform soluble ion- associates under specified experimental conditions are described. Three acidic dyes, namely Wool Fast Blue BL (WFB BL, method A), Tropaeolin ooo (Tpooo, method B), Naphthol Blue 12BR (NB 12BR, method C) were utilized. The extracts of the ion-associates exhibit absorption maxima at 580 nm, 480 nm, and 590 nm for methods A, B and C respectively. Beer's law and the precision and accuracy of the methods are checked by the UV reference method. The results are reproducible with an accuracy of ±1.0%. The methods are found to be suitable for the determination of dexmedetomidine in the presence of the other ingredients that are usually present in dosage forms.

SIMPLE AND SELECTIVE SPECTROPHOTOMETRIC ASSAY OF DIETHYLCARBAMAZINE CITRATE USING 2,3-DICHLORO-5,6-DICYANO-p-BENZOQUINONE AND 2,4-DINITRO PHENOL

Two simple, rapid and inexpensive spectrophotometric methods are described for the determination of diethylcarbamazine citrate (DEC) in bulk drug and formulations. The methods are based on the charge–transfer (CT) complexation reaction involving DEC as the n- donor and 2,3-dichloro-5,6-dicyano-p-benzoquinone [DDQ] (method A) and 2,4-dinitro phenol [DNP] (method B) as π-acceptors in chloroform. The absorbance of CT complexes was measured at 480 nm for method A, and 420 nm for method B. Under optimum conditions, Beer’s law was obeyed over the concentration ranges 4-90 and 4-100 μg mL-1 for methods A and B, respectively.

Simple and rapid spectrophotometric assay of albendazole in pharmaceuticals using iodine and picric acid as CT complexing agents

Two simple, rapid and inexpensive spectrophotometric methods are described for the determination of albendazole (ALB) in bulk drug and in tablets. The methods are based on charge-transfer (CT) complexation reaction involving ALB as n-donor and iodine as σ-acceptor (method A) in dichloromethane or picric acid (PA) as π-acceptor (method B) in chloroform. The absorbance of CT complexes was measured at 380 nm for method A, and 415 nm for method B. The optimization of the experimental conditions is described. Under optimum conditions, Beer's law obeyed over the concentration ranges 8.0-240 and 2.4-42 μg mL-1 for method A and method B, respectively. The apparent molar absorptivity of CT complexes at the respective λmax are calculated to be 1.17×103 and 5.22×103 L mol-1cm-1 respectively, and the corresponding Sandell sensitivity values are 0.2273 and 0.0509 ng cm-2. The limits of detection (LOD) and quantification (LOQ) are calculated to be (0.69 and 2.08), and (0.10 and 0.30) μg mL-1 with method A, and method B, respectively. The intra-day and inter-day accuracy expressed as % RE and precision expressed as % RSD were less than 3%. The methods were applied to the determination of ALB in tablets.

Two Spectrophotometric Methods for the Assay of Benzalkonium Chloride in Bandage Samples

AbstractTwo rapid, direct, extraction‐free spectrophotometric procedures were developed for the determination of benzalkonium chloride. The procedures were based on the formation of mixed dye‐surfactant aggregates between eosine Y and benzalkonium chloride (Method A), or between eosine B and benzalkonium chloride (Method B) in Clark‐Lubs medium by measuring the increase in absorbance at 556 and 550 nm, respectively. Beer's law was obeyed in the concentration range of 0.5–12 and 0.5–12 μg mL−1 for benzalkonium chloride with good precision and accuracy, whose limits of detection were 0.1 μg mL−1 at 556 nm for Method A and 0.2 μg mL−1 at 550 nm for Method B, respectively. The proposed procedures were successfully applied to the assay of benzalkonium chloride in bandages. The analytical results of the real samples were in good agreement with those by HPLC.

Utilization of a Green Brominating Agent for the Spectrophotometric Determination of Pipazethate HCl in Pure Form and Pharmaceutical Preparations

Five simple, accurate, and sensitive spectrophotometric methods (A–E) have been described for the indirect assay of pipazethate HCl (PZT) either in pure form or in pharmaceutical preparations. The proposed methods are based on the bromination of pipazethate HCl with a solution of excess bromate-bromide mixture in hydrochloric acid medium and subsequent estimation of the residual bromine by different reaction schemes. In the first three methods (A–C), the determination of the residual bromine is based on its ability to bleach the color of methyl orange, indigo carmine, or thymol blue dyes and measuring the absorbance at 520, 610, and 550 nm for methods A, B, and C, respectively. Methods D and E involves treating the unreacted bromine with a measured excess of iron(II), and the remaining iron(II) is complexed with 1,10-phenanthroline, and the increase in absorbance is measured at 510 nm for method D and the resulting iron(III) is complexed with thiocyanate and the absorbance is measured at 480 nm for method E. The different experimental parameters affecting the development and stability of the color are carefully studied and optimized. Regression analysis of the Beer-Lambert plots showed good correlation in the concentration ranges of 0.5–8.0 μg . The apparent molar absorptivity, Sandell's sensitivity, detection and quantitation limits were evaluated. The proposed methods have been applied and validated successfully for the analysis of the drug in its pure form and pharmaceutical formulations with mean recoveries of 99.94%–100.15% and relative standard deviation ≤1.53. No interference was observed from a common pharmaceutical adjuvant. Statistical comparison of the results with the reference method shows excellent agreement and indicates no significant difference in accuracy and precision.

Development and Validation of Spectrophotometric Methods for the Determination of Rasagiline in Pharmaceutical Preparations

This study presents three simple, rapid, and accurate spectrophotometric methods for the determination of Rasagiline (RSG) in pharmaceutical preparations. The determination procedures depend on the reaction of RSG with chloranilic acid for method A, tetrachloro-1,4-benzoquinone for method B, and 7,7,8,8-tetracyanoquinodimethane for method C. The colored products were quantitated spectrophotometrically at 524, 535, and 843 nm for methods A, B, and C, respectively. Different variables affecting the reaction were optimized. Linearity ranges of the methods with good correlation coefficients (0.9988–0.9996) were observed as 25–300 µg mL−1, 25–350 µg mL−1, and 50–500 µg mL−1for methods A, B, and C, respectively. The formation of products takes place through different mechanisms. The sites of interaction were confirmed by elemental analysis using IR and1H-NMR spectroscopy. The validation of the methods was carried out in terms of specificity, linearity, accuracy, precision, robustness, limit of detection, and limit of quantitation. No interference was observed from concomitants usually present in dosage forms. The methods were applied successfully to the determination of RSG in pharmaceutical preparations.

Validated spectophotometric methods for the assay of cinitapride hydrogen tartrate in pharmaceuticals

Three simple, selective and rapid spectrophotometric methods have been established for the determination of cinitapride hydrogen tartrate (CHT) in pharmaceutical tablets. The proposed methods are based on the diazotization of CHT with sodium nitrite and hydrochloric acid, followed by coupling with resorcinol, 1-benzoylacetone and 8-hydroxyquinoline in alkaline medium for methods A, B and C respectively. The formed azo dyes are measured at 442, 465 and 552 nm for methods A, B and C respectively. The parameters that affect the reaction were carefully optimized. Under optimum conditions, Beer?s law is obeyed over the ranges 2.0-32.0, 1.0-24.0 and 1.0-20.0 ?g. mL-1 for methods A, B, and C, respectively. The calculated molar absorptivity values are 1.2853 x104, 1.9624 x104 and 3.92 x104 L.mol-1.cm-1 for methods A, B and C, respectively. The results of the proposed procedures were validated statistically according to ICH guidelines. The proposed methods were successfully applied to the determination of CHT in Cintapro tablets without interference from common excipients encountered.

Spectrophotometric determination of linezolid in pharmaceuticals on the basis of coupled redox-complexation reactions

The present study describes three simple and sensitive spectrophotometric methods developed for the determination of linezolid (LZD) in pure and tablet forms. These methods are based on the oxidation of LZD by ferric chloride in the presence of 1,10-phenanthroline (method A), or 2,2′-bipyridyl (method B), or potassium ferricyanide (method C). The colored complexes were measured at 510, 522 and 758 nm for methods A, B and C, respectively. In all the methods, the absorbance is found to increase linearly with increasing LZD concentration. Beer’s law is obeyed over the concentration ranges of 0.5–6.0, 0.5–9.0 and 1.0–9.0 μg/mL for methods A, B and C, respectively. The calculated molar absorptivity values are 5.8 × 104, 3.6 × 104 and 4.8 × 104 L/mol cm for methods A, B and C, respectively, and the corresponding Sandell’s sensitivities are 5.8 × 10−3, 9.8 × 10−3 and 7 × 10−3 μg/cm2, respectively. The developed methods are applied successfully to the determination of LZD in the pharmaceutical formulations and the results tallied well with label claims.

Utility of Certain Nucleophilic Aromatic Substitution Reactions for the Assay of Ethamsylate in its Dosage forms and in Presence of its Degradation Product

The study represents the first report on the development of spectrophotometric methods for determination of ethamsylate (EST) in the presence of hydroquinone as an impurity and/or acidic degradation product. The proposed methods are based on the reaction of EST through it,s secondary amino group either with 1,2-naphthoquinone-4-sulphonate sodium (NQS) at pH 10.7 or 2,4-dinitrofluorobenzene (DNFB) at pH 9.3 to form orange and yellow colored reaction products peaking at 478 and 387 nm for methods (I) and (II), respectively. The different experimental parameters affecting the development and stability of the reaction products in methods (I) and (II) were carefully studied and optimized. The absorbance-concentration plots were rectilinear over the concentration ranges of 2-30 and 2-14 µg mL−1 for methods (I) and (II), respectively. The lower detection limits were 0.13 and 0.19 µg mL−1 and the lower quantitation limits were 0.44 and 0.63 µg mL−1 for methods (I) and (II), respectively. Both methods were successfully applied to commercial ampoules and tablets.