Quartz Cell Research Articles

SIMPLE AND SENSITIVE SPECTROPHOTOMETRIC ASSAYS FOR THE DETERMINATION OF TERBINAFINE HCL ANTIFUNGAL DRUG IN PHARMACEUTICALS

Objective: Two highly sensitive, accurate, inexpensive, and simple spectrophotometric assays were developed and validated for the determination of an anti-fungal drug, Terbinafine HCl (TBH), in pure drug and tablets using potassium permanganate (PP) and disodium 2-(1,3-dioxo-2,3-dihydro-1H-inden-2-yl)quinoline-6,8-disulfonate (DSOQ). Material and Method: In the present study, Sebifin and Terbiforce 250 mg tablets were used as pharmaceuticals, potassium permanganate KMnO4 and disodium 2-(1,3-dioxo-2,3-dihydro-1H-inden-2-yl)quinoline-6,8-disulfonate in water were used as reagents, and DR 3900 spectrophotometer equipped with 1cm matched quartz cells was used for absorbance measurements. Result and Discussion: The amount of terbinafine hydrochloride reacting with permanganate and disodium 2-(1,3-dioxo-2,3-dihydro-1H-inden-2-yl)quinoline-6,8-disulfonate in an acidic medium has been determined. The colored reaction products in both cases were measured at the maximum absorptions of 540 nm and 440 nm, respectively. The absorbance measured in each assay as a function of TBH concentration was related to TBH concentrations. Different experimental and variable conditions of assays were done carefully, accurately studied, and optimized. The validation of two assays also was done by following the current guidelines of the International Conference on Harmonization (ICH). Beer’s law for the two methods is obeyed over the concentration ranges 1-15 µg/ml (Correlation coefficient = 0.9983) and 1-18 µg/ml (Correlation coefficient = 0.9989) for methods PP and DSOQ, respectively. Molar absorptivity, limits of detection, and quantification (LOD & LOQ) values were (1.38×104 l/ mol cm, 0.92 & 2.78 µg/ml) for PP assay, and (1.73×104 l/ mol cm, 0.09 & 0.27 µg/ml) for DSOQ assay, respectively. The two assays were successfully applied for the determination of TBH in commercial tablets with reliable and satisfactory results, and hence the proposed assays can be applied in pharmaceutical laboratories of quality control.

THE SIMULTANEOUS SPECTRAL DETERMINATION OF CANDESARTAN CILEXETIL AND HYDROCHLOROTHIAZIDE IN TABLETS USING THE TRIVARIATE CLASSICAL LEAST SQUARES METHOD

Objective: Candesartan cilexetil (CDS) is a member of the sartan group of drugs and is widely used to lower blood pressure. Hydrochlorothiazide (HCT) is the most commonly used diuretic group of drugs and is prescribed together with candesartan cilexetil in cases where blood pressure cannot be reduced. Pharmaceutical preparations containing these two active compounds in combination are preferred today to provide a more effective pharmacological effect. Therefore, it is of great importance to determine the quantities of these combined pharmaceutical preparations with new analytical methods that are fast, easy, and sensitive in quality control and routine analysis. In this study, a new trivariate classical least squares calibration method (TCLS) was developed for the simultaneous quantification of candesartan cilexetil (CDS) and hydrochlorothiazide (HCT) in binary mixtures and commercial tablets without using a preliminary separation step. Material and Method: CDS and HCT compounds were kindly donated by National Pharm Ind., Turkey. HPLC-grade methanol (J.T. Baker, Netherlands) was used as a solvent for the spectrophotometric analysis. In the application of the TCLS method, the determination and quantification of CDS and HCT were carried out using UV spectrophotometric measurements with 1 cm quartz cells in the 200-310 nm spectral region (slit range 2 nm). The newly developed TCLS method was tested using a validation set consisting of eight synthetic mixture solutions within the working ranges of 4.0-20.0 μg/ml for CDS and HCT. Simultaneous quantification analyses of CDS and HCT were performed on ATACAND PLUS® Tablet supplied by Astra Zeneca İlaç Ltd Şti. Result and Discussion: The method is based on the application of TCLS to the absorbance measurements at three different wavelength points (223.5, 240.0, and 268.5 nm). The absorptivity values (µg-1mlcm-1) of pure CDS and pure HCT were 6.67x10-2, 2.76x10-2, 2.33x10-2, and 11.41x10-2, 0.46x10-2, 6.42x10-2 at the selected wavelengths, respectively. Recovery values and relative standard deviation values were calculated as 97.2% and 1.61% for CDS and 99.7% and 3.67% for HCT, respectively. This method was successfully applied to the spectrophotometric quantitative analysis of tablets containing CDS and HCT, and then, a good agreement was reported.

Etching Rate Analysis Model Based on Quartz Bond Angle Characteristics

This paper proposes a method for classifying crystal planes based on the bond angle characteristics of quartz unit cells and constructs an etch rate model for quartz crystal planes at both macro and micro scales. By omitting oxygen atoms from the quartz cell structure, a method based on bond angle characteristics was established to partition the atomic arrangement of the crystal surface. This approach was used to analyze the etching processes of typical quartz crystal planes (R, r, m, and (0001)), approximating the etching process of crystals as a cyclic removal of certain bond angle characteristics on the crystal planes. This led to the development of an etch rate model based on micro-geometric parameters of crystal planes. Additionally, using the proposed bond angle classification method, the common characteristics of atomic configurations on the crystal plane surfaces within the X_cut type were extracted and classified into seven regions, further expanding and applying the etch rate model. The computational results of this model showed good agreement with experimental data, indicating the rationality and feasibility of the proposed method. These also provide a theoretical basis for understanding the microstructural changes during quartz-based MEMS etching processes.

Development of the spectrophotometric method for the determination of meldonium in capsules by using alizarine

The aim of the work was to develop a simple, rapid, economic spectrophotometric method for the determination of meldonium in capsules based on the reaction with alizarin.
 Materials and methods. Analytical equipment: double-beam UV-visible spectrophotometer Shimadzu UV 1800 (Japan), a pair of 1 cm matched quartz cells, software UV-Probe 2.62, laboratory electronic balance RAD WAG AS 200/C, pH-meter И-160МИ. Pharmacopoeial standard sample (CRS) of meldonium dihydrate (Sigma-Aldrich, (≥ 98 %, HPLC)), alizarin (Synbias), capsules Metamax (Darnytsia) 250 mg, Vasopro (Farmak) 500 mg, Mildronate (Grindex) 500 mg, dimethylformamide (“Honeywell Riedel-de Haen”).
 Results and discussion. A spectrophotometric method for determining meldonium in capsules by reaction with alizarine has been developed. The absorption maximum of the formed complex in dimethylformamide was at a wavelength of 517 nm. Stoichiometric ratios of reactive components «meldonium- alizarin» were 1:1. Validation of the developed analytical method for the determination of meldonium in medicines was carried out in accordance with the requirements of the SPhU. The optimal conditions for performing the quantitative determination of meldonium have been established: concentration of alizarin solution – 0.8 %, volume 0.8 % alizarin solution – 0.5 ml, heating time – 20 min, temperature – 95+/- 2 °C. Linearity has been in the concentration range of 0.0402- 0.1073 mg/mL, the limit of detection - 2.84 μg/mL, and the limit of quantification – 8.59 μg/mL. The eco-friendliness of the developed analytical method was carried out using the analytical eco-scale, AGREE, and GAPI methods.
 Conclusions. The developed method can be used as an arbitration method for the routine analysis of meldonium capsules

UV spectrophotometric determination of chlorthalidone in tablet dosage form by using single point standardization method

The current research endeavors to elucidate the creation of an uncomplicated, highly sensitive, swift, precise, and cost-effective UV-accepted spectrophotometric method for the quantitative assessment of Chlorthalidone. This is achieved through the utilization of a visible spectrophotometric approach employing single-point standardization and calibration plot methods, for pharmaceutical dosage forms. The equipment employed includes a double-beam UV-visible spectrophotometer, specifically the Shimadzu Model UV1800, with 1cm quartz cells and 0.2 M Sodium hydroxide serving as the solvent. Notably, an absorption maximum is identified at 219 nm. The developed method strictly adheres to Beer’s law. In the case of single-point standardization, the percentage of Chlorthalidone detected falls below the labeled claimed limit. Simultaneously, the tablet formulation is subjected to a percentage purity test using the calibration plot method, revealing that the observed quantity of Chlorthalidone is below the labeled content. This suggests a potential discrepancy in the marketed product of Chlorthalidone, indicating a probable deficiency in the therapeutic effect of the formulation due to the lower amount of Chlorthalidone present. The overall efficacy of the product hinges on the quality assurance of its constituents.

Simultaneous Determination of Iron and Copper in Aqueous Solution Using Spectrophotometry

Iron and copper mixtures were quantitatively determined in aqueous solutions for the first time using the analytical method in this approach with the aid of T60U Spectrophotometer. The method is so simple, fast, economic, and can be carried out easily on a bench. The absorbencies for iron, copper and iron-copper mixtures in aqueous solution were measured using T60U adopted with UVWin6 software UV -VIS Spectrometer (pg instruments United Kingdom) by filling two 5 ml quartz cells of dimensions 1*1*5 cm, the first is filled with the blank solution which is a solution containing all the constituents of the sample except iron and copper and the other quartz cell is filled with the stock solution iron and/or copper under investigation. Absorbency of iron was determined by setting T60U spectrometer wavelength at 504 nm, meanwhile for copper absorbency measurements the apparatus is set at 304 nm. Iron, copper, and iron-copper mixture calibration curves were of very high accuracy with the least linear regression value of ≤ 1, i, e the measured data were of relative standard deviation value (RSD) of ≤ 1.5%.

Photophysical and photodynamic analysis of different formulations of riboflavin

Background: Riboflavin (Rb) has been used in the ophthalmological procedure known as corneal cross-linking (CXL). Pathologies requiring this treatment include keratoconus, corneal ectasia, and infectious keratitis. Rb is instilled via different molecules that are transported into the tissues. However, each vehicle imparts different properties that alter the photodynamic behavior of Rb, leading to variable concentrations of free radicals within the medium. The objective of this study was to measure the concentrations of free radicals produced by commonly used Rb formulations. To determine the free radical production level of each formulation, L-tryptophan (L-Tryp) was used as a model substrate because it can be efficiently photo-oxidized.
 Methods: We investigated the photodegradation of L-Tryp and its kinetics upon light exposure. The spectra were recorded using a Shimadzu UV-1800 PC spectrophotometer and a Cary Eclipse fluorescence spectrophotometer. A high-power solid-state LED light source was used for irradiation. L-Tryp degradation was performed using a 9-W LED lamp, and steady-state photolysis was conducted in quartz cells. The observed rate constants for L-Tryp degradation were determined by analyzing the changes in absorbance and fluorescence intensity. Data analysis was performed using Origin software.
 Results: We examined the characteristics of the photophysical and photodynamic action of the carriers in different commercially available Rb formulations. These included a) Rb with dextran, b) Rb without dextran, c) VibeX Rapid® (hydroxypropylmethylcellulose as a vehicle), d) Trans-Epithelial Kit (I) (sodium chloride as a vehicle), and e) Trans-Epithelial Kit (II) (benzalkonium chloride as a vehicle), using L-Tryp as a model substrate, and focusing on absorption and emission spectra. VibeX Rapid® exhibited the highest photo-degradation constant. The study affirmed the stability of Rb formulations for CXL and highlighted the efficacy of VibeX Rapid® in L-Tryp photo-oxidation and this rationalizes its current use as a CXL agent.
 Conclusions: We demonstrated that formulations for transport of Rb are of crucial importance in CXL applications. Rb in the VibeX Rapid® formulation is more effective in generating photo-degradation, and this reflects its superior performance in CXL. Future experiments should be designed and conducted to quantitatively differentiate the production of free radicals. Studies involving human participants could shed light on the clinical efficacy and safety of the available Rb formulations.

CHEMOMETRIC ASSISTED UV SPECTROPHOTOMETRIC METHOD FOR QUANTIFICATION OF EMTRICITABINE AND TENOFOVIR DISOPROXIL FUMARATE

The aim of this study was to verify the ability of the UV spectrophotometric method for the simultaneous determination of emtricitabine and tenofovir disoproxil fumarate in tablet dosage form using the principal Component Regression (pCR) and partial Least Squares (pLS) multivariate calibration methods. Double beam UV-Vis spectrophotometer (Jasco V-730) with 1 cm quartz cell with 1 nm data interval and scanning speed of 400 nm min -1 was used in the study. the optimized wavelength range selected was 225-275 nm. the data obtained was processed using Unscrambler X (10.5) (64bit) software. The developed models showed good results over the concentration range of 6-36 μg mL -1 for tenofovir disoproxil fumarate and 4-24 μg mL-1 for emtricitabine with co-relation coefficient greater than 0.995 and % RSD less than 2%. the accuracy studies show % recovery within limits. The method was validated as per ICH Q2(R1) guideline.

Controlling Circularly Polarized Luminescence Using Helically Structured Chiral Silica as a Nanosized Fused Quartz Cell.

Circularly polarized luminescence (CPL) is typically achieved with a chiral luminophore. However, using a helical nanosized fused quartz cell consisting of chiral silica, we could control the wavelength and helical sense of the CPL of an achiral luminophore. Chiral silica with a helical nanostructure was prepared by calcining a mixture of polyhedral oligomeric silsesquioxane (POSS)-functionalized isotactic poly(methacrylate) (it-PMAPOSS) and a small amount of chiral dopant. The chiral silica encapsulated functional molecules, including luminophores, along the helical nanocavity, leading to induced circular dichroism (ICD) and induced circularly polarized luminescence (iCPL). Because chiral silica can act as a helical nanosized fused quartz cell, it can encapsulate not only the luminophore but also solvent molecules. By changing the solvent in the luminophore-containing nanosized fused quartz cell, the wavelength of the CPL was controlled. This method provides an effective strategy for designing novel CPL-active materials.

Method Development and Validation of UV-Spectrophotometric Estimation of Hydroxychloroquine Sulphate in Bulk and Pharmaceutical Dosage Form

Aims: The devised method for estimating hydroxychloroquine sulphate in bulk and pharmaceutical dose forms (tablets) is the subject of this work. The method can therefore be applied to regular quantitative analysis and stability. The following describes the planned work's goal and scope:
 
 To create an appropriate spectrophotometric method for tablet-based hydroxychloroquine sulphate estimation.
 Carry out the method's validation.
 
 Methodology: These techniques include the area under curve (AUC) method-I and the A1% solution method based on absorbance measurement, or method-II, both of which are chosen at wavelengths of 329.4 nm using a UV-visible spectrophotometer with a 1 cm matched quartz cell and 0.01N acetic acid with water as a solvent.
 Results: Plots of the hydroxychloroquine sulphate absorption spectra in 0.01N acetic acid were made. 329.4 nm was found to be the average maximum. With correlation coefficients of 0.9992 and 0.999 (r2>0.999) for AUC and 1%, respectively, and a linear connection between the absorbance and drug concentration in concentration ranges of 5-35 g/mL, it is clear that the method is linear. The percentage of medication calculated by various methods was close to 100.12, and 99.41% of the results were consistent with the label claim of the commercially available tablet formulation. As per ICH requirements, the validation parameter research was completed.
 Conclusion: The described UV methods offer good accuracy and precision with reduced limits of detection and quantification. They are straightforward, trustworthy, and highly selective. These disclosed methods are ideal for routine quantitative analysis in pharmaceutical dosage forms due to the decreased time required for analysis of hydroxychloroquine sulphate. The time-saving, low-cost alternative to the expensive high-performance liquid chromatographic technology is the applied spectrophotometric approaches.

Experimental analysis of heat and mass transfer in non-isothermal sloshing using a model-based inverse method

Nonisothermal liquid sloshing in partially filled reservoirs can significantly enhance heat and mass transfer between liquid and ullage gasses. This can result in large temperature and pressure fluctuations, producing thrust oscillations in spacecraft and challenging thermal management control systems. This work presents an experimental characterization of the thermodynamic evolution of a cylindrical reservoir undergoing sloshing-induced thermal de-stratification. We use a 0D model-based inverse method to retrieve the heat and mass transfer coefficients in planar and swirl sloshing conditions from the temperature and pressure measurements in the liquid and the ullage gas. The experiments were carried out in the SHAKESPEARE shaking table of the von Karman Institute in a cuboid quartz cell with a cylindrical cut-out of 80 mm diameter in the center, filled up to 60 mm with the cryogenic replacement fluid HFE-7200. A thermal stratification with ΔT=25 K difference between the ullage gas and liquid was set as the initial conditions. A pressure drop of 90% in the ullage gas was documented in swirling conditions. Despite its simplicity, the model could predict the system’s thermodynamic evolution once the proper transfer coefficients were derived.

Electrical Conductivity and Molar Volume of (LiCl-KCl)eut.–CsCl Molten Mixtures

The electrical conductivity of (LiCl-KCl)eut.–CsCl molten mixtures has been measured over a concentration range of 0–100 mol % CsCl and in a wide temperature span (624–1180 K). The measurements were carried out in quartz cells of the capillary type with platinum electrodes using the AC-bridge method. The molar volume of these mixtures was estimated using similar literature data. The maximum deviations of the molar volume from the additive values are ∼2%. Molar conductivity and its activation energy were calculated using the derived molar volume data. It was found that the electrical conductivity of all melts increases with increasing temperature and decreases with increasing CsCl concentration. In the molten (LiCl-KCl)eut.–CsCl mixtures, the significant negative deviations of the specific and molar electrical conductivities from additive values are observed over the whole concentration range, which indicates that the replacement of one alkaline cation by those, significantly different in size, is accompanied by a noticeable rearrangement of interparticle bonds. Therefore, the complexation in the system becomes different. According to the obtained data on electrical conductivity, the liquidus line of this system was built.

Comparative Spectrophotometric Determination of Neodymium (III), Praseodymium (III), Samarium (III) and Terbium (III) in Aqueous and Micelle Media

This research work titled comparative spectrophotometric determination of neodymium (III), praseodymium (III), samarium (III) and terbium (III)in aqueous and micelle media using schiff base was carried out with the aim to use a simple, rapid and sensitive spectrophotometric method for the determination of Nd (III), Pr (III), Sm(III) and Tb(III) using the Schiff base 2,2′-((1E,1′E)-(1,2-phenylenebis(azanlylidene)bis (methanylylidene))diphenol (BSOPD) as a ligand. Spectral and absorbance measurements were carried out using UV/Visible Spectrophotometer (Jenway model no.: 6305) with 1-cm matched quartz cells. This method of experiment was based on the formation of green coloured complexes, upon the reaction of Nd(III) and Pr(III) and a brown coloured complexes for Sm(III) and Tb(III) having a maximum absorbance of 376, 386, 384 and 380 nm respectively. The comparative analysis of the complexes formed in aqueous and in micellar media were investigated in this study. In the obtained results, it was discovered that, Beer’s law was obeyed in the concentration ranges of 0.001 - 0.02 ppm. The molar absorptivity was found to be in the range of 7,776- 23,197 and 27,087 dm³mol^-1cm^-1 and the Sandell’s sensitivity for the compounds analyzed were in the ranges of 6.13-19.34 g cm^-2. The increase in absorbance in the presence of the surfactants is due to micelle formation. The reactants were bound in a small volume of stern layer of the micelle leading to a greater increase in concentration effect. This effect in concentration reaches a maximum before decreasing due to dilution effect occasioned by increase in metal ion concentration.

Development of the spectrophotometric method for the determination of metoprolol in tablets by using bromophenol blue

The aim of the work was to develop a simple, economical and eco-friendly spectrophotometric method for determining metoprolol tartrate in tablets based on the reaction with bromophenol blue (BPB).
 Material and methods: A double–beam Shimadzu UV-Visible spectrophotometer, with a spectral bandwidth of 1 nm wavelength accuracy ±0.5 nm, Model –UV 1800 (Japan), Software UV-Probe 2.62, and a pair of 1 cm matched quartz cells, was used to measure the absorbance of the resulting solution. All the chemicals were used in analytical reagent grade. Pharmacopeial standard samples of metoprolol tartrate and bromophenol blue (BPB) were provided by Sigma-Aldrich (≥ 98%, HPLC). The used dosage forms of metoprolol tartrate are tablets of Metoprolol 50 mg and 100 mg.
 Results and discussion: The method of spectrophotometric determination of the quantitative content of metoprolol tartrate based on its reaction with BPB in a methanol solution has been developed. The stoichiometric ratios of the reactive components as 1:1 were obtained by the methods of continuous changes and the saturation method. The developed method of quantitative determination of metoprolol tartrate was validated. The linearity regression equation was y = 0.0373x + 0.0038, and the obtained correlation coefficient was R2=0.9984. A linear relationship was found between absorbance at λmax and concentration of metoprolol tartrate in the range of 9.56-15.02 µg/mL. The LOD and LOQ values were calculated to be 0.81 µg/mL and 2.67 µg/mL.
 Conclusions. A simple, economical and eco-friendly spectrophotometric method has been developed for the quantitative determination of metoprolol tartrate in tablets based on the reaction with BPB. The developed method of quantitative determination of metoprolol tartrate was validated in accordance with the requirements of SPhU. We suggest our work with offered detailed and successful solutions for the mentioned aim with less sophisticated equipment for QC lab for routine manufacturing control

Experimental Determination of the Effective Areas of Effusion Orifices in Knudsen Quartz Cells

Experimental Determination of the Effective Areas of Effusion Orifices in Knudsen Quartz Cells

Development and Validation of a Simple Spectrophotometric Method for Quantitative Determination of Sodium Diclofenac in Modified-Release Tablets

In this study, a rapid, simple, economical and accurate spectrophotometric process was developed for the determination of sodium diclofenac in modified release tablets using ethanol 96% as an available and non-toxic solvent. Sodium diclofenac standard solution was scanned under UV (200-400 nm) in a 1 cm quartz cell to determine the maximum absorption wavelength which was 285 nm. This method was validated in accordance with the requirements of the International Conference on Harmonization (ICH), where the calibration curve showed linearity in the studied concentration range (5-30 μg mL-1) with correlation coefficient R² = 0.9993. The relative standard deviation of the accuracy studies was within the acceptable range (<2%). This method also achieved an excellent recovery ratio (Mean recovery ± S.D. = 100.44% ± 0.81) with high sensitivity (limit of detection 1.10 μg mL-1 and quantitation limit of 3.34 μg mL-1). The developed process applied successfully to determine sodium diclofenac in four commercial pharmaceuticals products (A, B, C and D) marketed locally as modified-release tablets. The product C showed the highest assay value 106% and product B showed the lowest value 98%. Hence, we recommend using this method to quantitatively determine of sodium diclofenac in pharmaceutical dosage forms.

Tunable Multicolor Circularly Polarized Luminescence via Co-assembly of One Chiral Electron Acceptor with Various Donors

Tunable Multicolor Circularly Polarized Luminescence via Co-assembly of One Chiral Electron Acceptor with Various Donors

Highly Ordered Supramolecular Assembled Networks Tailored by Bioinspired H-Bonding Confinement for Recyclable Ion-Transport Materials

Highly Ordered Supramolecular Assembled Networks Tailored by Bioinspired H-Bonding Confinement for Recyclable Ion-Transport Materials

Desorption of polycyclic aromatic hydrocarbons by cosmic rays

Context. The rate of sputtering and release of condensed species is an important aspect of interstellar chemistry, as is photodesorption for the most volatile species, because in the absence of such mechanisms the whole gas phase would have to condense in times often shorter than the lifetime of the considered medium, in particular for dense clouds. The recent detection of cyclic aromatic molecules by radioastronomy requires an understanding of the potential mechanisms supporting the rather high abundances observed. Aims. We perform experiments to advance our understanding of the sputtering yield due to cosmic rays for very large carbonaceous species in the solid phase. Methods. Thin films of perylene and coronene were deposited on a quartz cell microbalance and exposed to a 1.5 MeV N+ ion beam at the Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab, Orsay, France) and a 230 MeV 48Ca10+ ion beam at the GSI Helmholtzzentrum für Schwerionenforschung (GSI, Darmstadt, Germany). The mass loss was recorded as a function of the fluence for the N+ beam. The microbalance response was calibrated using Fourier transform infrared (FTIR) reflectance measurements of the produced films. In addition, the destruction cross-section of the same species was measured with the 48Ca10+ ion beam by in situ monitoring of the evolution of the infrared spectra of the bombarded films. Results. We deduced the sputtering yield for perylene and coronene and their radiolysis destruction cross-sections. Combining these results with a cosmic ray astrophysical spectrum, we discuss the impact on the possible abundance that may originate from the sputtering of dust grains with these molecules as well as from polycyclic aromatic molecules when they are trapped in ice mantles.

DEVELOPMENT OF SPECTROPHOTOMETRIC METHOD FOR DETERMINATION OF LISINOPRIL IN TABLET DOSAGE FORM

Aim. The research aims at developing a fast, simple, reliable spectrophotometric method according to "green" chemistry principles for the determination of lisinopril in pure substance and in drugs presented on the Ukrainian market.
 Materials and Methods. Chemical reference standard of lisinopril dihydrate (Sigma-Aldrich, ³98%, HPLC), methanol R (Honeywell Riedel-de Haen™, 99.9%), tablets of Lisinopril-Astrapharm 10 mg), Lisinopril-KRKA 10 mg (Slovenia) and Lisinopril-Teva 10 mg (Germany) were used in this study. Double-beam scanning spectrophotometer "Shimadzu UV-1800" (Japan) connected with software package UV-Probe 2.62 were used for measurements. Absorbance of the solutions in the UV region were recorded in 1 cm quartz cells vs. methanol R. Laboratory electronic balance RAD WAG AS 200 / C, ultrasonic bath Sonorex Digitec DT100H and measuring glassware of grade A were used. Statistical processing and determination of validation parameters were performed in accordance with the requirements of State Pharmacopoeia of Ukraine 2.0 and ICH Q2.
 Results and Discussions. The spectrophotometric method for the determination of lisinopril by direct measurement of the absorbance of the tested solutions in the ultraviolet region of the spectrum has been developed (lmax=212 nm). Validation parameters including linearity, range of application, specificity, accuracy, precision, limit of detection and limit of quantification, robustness were calculated for the proposed analytical procedure. The correctness of the analytical method was proved by calculating the complete uncertainty of the latter. The calculated uncertainty of sample preparation (DSP) for the determination of lisinopril in tablets was 2.46%. It was established that the maximum contribution to the uncertainty of sample preparation for operations of the quantification of lisinopril in tablets, make the operations of lisinopril CRS sampling and aliquots pipetting. The total uncertainty of the analytical procedure (DAs) in the analysis of the drug was 2.56%. The predicted complete uncertainty of the analysis results did not exceed critical values (DAs=2.56 % £ maxDAs=3.2 %), the method is correct. The specificity is proved by the absence of interfering influence of excipients due to nonoccurence of absorption at the analytical wavelength in the analysis of methanolic extract of placebo-tested tablets, Beers law was obeyed in the ranges of 20-100 mg / ml. The least squares method was used for statistical processing of the results. Regression analysis yielded the following calibration equation: y=26,791x-0,4398. The limit of detection and the limit of quantification were 2,3 і 6,9 mg/ml. Robustness of the method was estimated by studying of absorbance stability changes of tested solutions over time. Robustness was assessed by studying the absorbance stability of the tested solutions over time. It was found that freshly prepared solutions should be used within 100 min. Developed procedure for lisinopril determination in pure substance and tablet dosage form proved to be an excellent green analysis according to analytical eco-scale.
 Conclusions. Fast, simple, reliable, cost-effective, in accordance with the principles of "green" chemistry spectrophotometric method for determination of lisinopril in pure substance and tablets has been proposed. Validation of the analytical procedure on the parameters of linearity, application range, specificity, accuracy, precision, robustness, limit of detection and limit of quantification was carried out. The complete uncertainty of the analytical procedure at the level of 2.56% was obtained, which proves the possibility of obtaining correct analysis results in other laboratories.