Mean Centering Of Ratio Spectra Research Articles

Cutting-edge HPLC and MCR techniques for synchronically quantifying anticholinergic drugs in the presence of C12 and C14 homologs: Robust application to green and white chemistry.

Green and white chemistry are vital to revolutionizing the chemical industry through their unparalleled potential to enhance sustainability and efficiency. In this study, nine sustainability tools of both green and white metrics, including green analytical procedure index (GAPI), ComplexGAPI, analytical greenness, analytical greenness metric for sample preparation, Analytical Eco-Scale (ESA), analytical method greenness score, high-performance liquid chromatography- environmental assessment tool (HPLC-EAT), analytical method volume intensity, and blue applicability grade index (BAGI), have been developed for appraising environmental friendliness for both innovative and straightforward mean centering of ratio spectra (MCR) and reversed-phase high-performance liquid chromatography (RP-HPLC)strategies utilized for concurrent analysis and separation of cyclopentolate (CYC) and C12 and C14 homologs of benzalkonium chloride (BNZ) in pure and ophthalmic solution. The mobile phase, formed of buffer phosphate and acetonitrile (35:65, v/v), was adjusted to pH 6.3, and 215-nm UV detection was used. The experimental flow rate was 2.0 mL min-1, and the analytical column was L11 Inertsil Ph-3 (150 mm × 4.6 mm, 5 µm). All sequences were run at 25°C in the column oven. The MCR approach effectively resolved the drug's spectral overlapping. CYC and BNZ employed this approach at 227.5 and 220.4 nm, respectively. As part of the HPLC analysis, an isocratic method was employed with phosphate buffer and acetonitrile in the mobile phase at 35:65. A correlation coefficient greater than 0.999 was observed between the calibration curves for the HPLC and MCR methods in the ranges of 20-320 µg mL-1 and 5-30 µg mL-1 for all drugs. The technique yields excellent primary recovery rates, ranging from 97.2% to 100.5%. The recommended approach has been validated according to International Council for Harmonizationguidelines.

Facile synthesis and eco-friendly analytical methods for concurrent estimation of selected pharmaceutical drugs in their solutions: application to quality by design, lean six sigma, and stability studies

Economical, highly robust, selective, precise, and eco-friendly RP-UPLC and spectrophotometric methods were developed and validated for the concurrent estimation of selected pharmaceutical drugs represented in ceftazidime (CFZ) and pyridine (PYD) in their solutions using Agilent Zorbax SB-C18 RRHD (50 × 2.1 mm, 1.8 μm) column at flow rate 0.3 mL/min with wavelength 254 nm. Box-Behnken design (BBD) established Response surface methodology (RSM) to achieve the optimum chromatographic condition with minimal trials conducted. Three independent variables specifically acetonitrile ratio 60–70%, pH 3–7, and temperature 25–35 °C were implemented to evaluate the influences of these variables on the responses as resolution and retention time. Desirability and overlay plots were carried out to adjust the optimal condition that achieved the shortest retention time of less than 2 min and desired resolution of more than 1.5 using a mobile phase consisting of acetonitrile: purified water (70:30, v/v) at pH 5.0 adjusted by 0.1% orthophosphoric acid with the column oven temperature 30 °C and column void volume 0.46 mL. Mean centering of ratio spectra (MCR) and ratio subtraction (RS) methods were effectively applied to resolve drugs' spectral superposition at 220 nm, 255.4 nm, 260.3 nm, and 254.6 nm for CFZ and PYD, respectively. Linearity range was accomplished for UPLC, MCR, and RS methods over the concentration range of 2–100, 1–50,3–30 and 5–30 µg/mL for CFZ and PYD, respectively with correlation coefficient > 0.999 and good recovery results within 98–102%. Six Sigma methodology was achieved using the process capability index (Cpk) to compare the suggested and USP methods showing that both are highly capable with Cpk > 1.33. The proposed method was successfully validated depending on ICH guidelines and ANOVA results and applied for the accelerated stability study.Graphical

Three developed spectrophotometric methods for determination of a mixture of ofloxacin and ornidazole; application of greenness assessment tools

This work is dedicated to the greenness estimation of three proposed spectrophotometric techniques [e.g., ratio difference (RD), mean centering of ratio spectra (MCR) and continuous wavelet transform of ratio spectra (CWT)] for the determination of a binary combination named Ofloxacin (OFL) and Ornidazole (ORN). Applying the green analytical chemistry methods to assess the proposed methods has widely attained the analytical community care. The greenness assessment was performed via three evaluation approaches; the “Analytical Eco-Scale”, the “National Environmental Method Index” (NEMI) and “Green Analytical Procedure Index” (GAPI). Following the examination of the zero spectrum of OFL and ORN, it is observed that OFL and ORN spectra are overlapped, so they can be detected by the methods mentioned previously. The ratio difference method was carried out at wavelengths of 294.6 nm and 265.6 nm for OFL, 292 nm and 315 nm for ORN. The linear range was (2–15 µg/mL) for OFL and (3–30 µg/mL) for ORN. The MCR method based on the use of mean centered ratio spectra in dual steps and calculating the second ratio spectra mean centered values at 294.6 nm for OFL and 315 nm for ORN. The continuous wavelet transformation which carried out using MATLAB at wavelengths of 265 nm for OFL and 306 for ORN. These techniques were intended for the binary mixture analysis in bulk powder and pharmaceutical formulations with high recoveries. The developed methods were validated according to ICH guidelines. All techniques were statistically compared to either an official method for OFL or a reported method for ORN and the results indicate that there were not any significant differences.

Simultaneous determination of mometasone furoate and calcipotriol in a binary mixture by validated HPLC and chemometric-assisted UV spectrophotometric methods and identification of degradation products by LC-MS.

A new binary mixture containing mometasone furoate (MF) and calcipotriol (CP) is suggested to manage psoriasis; since the combined stability profile of these drugs is poorly understood. Herein MF, CP, and their mixtures were subjected to various stress conditions. Also, stability-indicating HPLC was developed and validated according to ICH guidelines with Box-Behnken design. The degradation products (DPs) were predicted in silico and identified using LC-MS. The bioactivity and toxicity of DPs were studied using molecular docking and alamarBlue assay, respectively. Spectroscopic techniques of the first derivative, first-derivative ratio, and the mean-centering of ratio spectra were also used to determine MF and CP in the mixture because of spectra overlapping. The major degradants for MF in alkaline conditions were DP1, DP2, and DP3, while in thermal and UV conditions, only DP1 was generated. CP gave one degradant in all conditions. No new impurity was observed in the MF and CP mixtures. The results of spectrophotometry showed good linearity in the range of 4-50 and 2-20 µg/ml, while linearity for HPLC was in the range of 4-50 and 0.5-2.5 µg/ml for MF and CP, respectively. Recovery was 99.61-100.38% for UV and 100.4% for HPLC methods of MF and 100.6-101.4% for UV and 99.5% for HPLC methods of CP. The developed methods can be used as simple, accurate, precise, and rapid techniques for routine quality control of MF and CP mixtures.

Fourier Transform Infrared Spectroscopic, Spectrofluorimetric Assays of Canagliflozin, and Stability-Indicating UV-Spectrophotometric Method for the Simultaneous Determination of Canagliflozin and Metformin.

Green Fourier transform infrared (FTIR) spectroscopy, using potassium bromide (KBr) disc technique, eliminates the consumption of hazardous chemicals. Spectrofluorimetry for drugs that have native fluorescence. Mean centering of ratio spectra (MCRS) analysing overlapped spectra without preliminary separation. Three simple, accurate, and sensitive methods have been developed and validated for the determination of canagliflozin (CANA); one is a stability-indicating method for CANA and metformin (MET) determination. Method A is FTIR using a KBr disc for CANA determination measuring alkyl halide C-F peak area centered on 1230/cm. Method B is spectrofluorimetry using Δ λ = 50 nm synchronous mode at a peak maximum of 291.8 nm for CANA determination using methanol as solvent. Method C is a stability-indicating MCRS method measuring the peak amplitude of CANA and MET at 306.2 and 246.6 nm, respectively, in their mixture with complete CANA oxidation degradation. The linear ranges were: FTIR spectroscopy, 1.50-24.70 μg/mg CANA; spectrofluorimetry, 100.00-600.00 ng/mL CANA; and MCRS, 1.00-25.00 μg/mL CANA and 1-30 μg/mL MET. All results were statistically compared with a reported method: no significant difference was observed. The proposed methods can be used efficiently for routine analysis in QC laboratories. A green FTIR method utilizes only one reagent, KBr. Spectrofluorimetry using a constant wavelength synchronous scan of CANA native fluorescence in nanogram concentrations overcomes conventional excitation/emission spectra drawbacks and proves that the solvent effect in the fluorescence intensity differs according to concentration used. Stability-indicating MCRS determines the studied drugs in bulk, pharmaceutical formulations, accelerated and long-term stability study samples.

Simultaneous determination of cefixime and erdosteine in combined dosage form using validated spectrophotometric methods.

Four accurate and precise spectrophotometric methods were developed and validated for the simultaneous determination of a binary mixture of cefixime (CEF) and erdosteine (ERD) without previous separation. Method A was first derivative ratio spectrophotometric method (1DD) where the amplitudes at 310 and 315nm and the amplitude at 248nm were chosen to simultaneously estimate CEF and ERD, respectively. Method B depends on ratio difference spectrophotometry (RDSM), in which the difference in amplitudes at 325 and 326nm on the ratio spectrum of the mixture was directly proportional to the concentration of CEF; independent of the interfering component. Similarly, the amplitude difference between 236 and 249nm on the ratio spectrum was used for the determination of ERD. Method C was based on simultaneous determination of CEF and ERD using classical least squares (CLS) and partial least squares (PLS) chemometric techniques. Method D was the mean centering of ratio spectra (MCR) at 313 and 237nm for the determination of CEF and ERD respectively. The developed methods were successfully employed to the determination of CEF and ERD in laboratory prepared mixtures and dosage form showing satisfactory recoveries. Methods validation was performed according to the International Conference on Harmonization (ICH) guidelines. The obtained results were statistically compared to those of the reference method, revealing no significant difference with respect to precision and accuracy. Precision and cost effectiveness of the developed methods permit their application in quality control laboratories for the determination of the binary mixture.

Simultaneous determination of Nebivolol hydrochloride and Valsartan in their binary mixture using different validated spectrophotometric methods.

Five simple, sensitive, accurate and precise spectrophotometric methods were developed for the simultaneous determination of Nebivolol hydrochloride (NEB) and Valsartan (VAL) in their binary mixtures and in pharmaceutical dosage form. The methods included Ratio Difference, First Derivative ratio, Mean Centering of ratio spectra, Bivariate and H-Point Standard additions method. The calibration curves were linear over the concentration range of 10-70μg/ml and 20-60μg/ml for NEB and VAL, respectively for Ratio Difference and First Derivative ratio method and over the concentration range of 10-70μg/ml and 10-60μg/ml for NEB and VAL, respectively for Mean Centering of ratio spectra, Bivariate and H-Point Standard additions method. These methods were examined by analyzing synthetic mixtures of the studied drugs and they were utilized to determine the studied drugs in their commercial pharmaceutical preparation. All methods were validated as per ICH guidelines and accuracy, robustness, repeatability and precision were found to be within the acceptable limits. The results of the proposed methods were compared to the results of reported methods with no significant difference between them.

Green spectrophotometric approaches for simultaneous analysis of tomato pesticides in commercial formulations and environmental samples

Tomatoes are in the top ten fruits and vegetables for containing levels of pesticide residues. In this study, three green accurate simple spectrophotometric methods were introduced for estimation of the collectively sprayed tomato pesticides, hexythiazox (HX), imidacloprid (IM), and thiamethoxam (TH). The first method depends on measuring the amplitude values at 248, 207 and 228 nm for HX, IM and TH, respectively after obtaining their mean centered ratio spectra. The second one is based on subtracting two amplitude values on ratio spectra of the pesticides mixture, which cancel out the interference of two of them and allows the determination of the third one. The two subtracted amplitude values were 204.8–215.6, 215.6–217.6, and 217.2–228.4 nm, for HX, IM and TH, respectively. The last method uses three successive derivatization steps on the ratio spectra after which HX, IM and TH can be determined at 211.4, 205.4, and 230.8 nm, respectively. The introduced methods were validated according to international conference on harmonization (ICH) recommendations and were proven to be suitable for the assay of HX, IM, and TH in commercial formulations, and field tomato samples using very simple extraction steps. The eco-friendliness of the developed methods was assessed using the Eco-scale analytical tool. The obtained score adds on the minimum environmental hazards to the several advantages of our proposed methods.

Manipulating Mean Centering of Ratio and First Derivative of Ratio Spectra Methods for Simultaneous Determination of Formoterol Fumarate and Budesonide in Drug Substances and Combined Pressurized Metered Dose Inhaler

Two smart and selective spectrophotometric methods namely mean centering of ratio spectra and first derivative of ratio spectra have been described and validated for simultaneous determination of Formoterol Fumarate and Budesonide in Pressurized Metered Dose Inhaler. Mean centering of ratio depends on using the mean centered ratio spectra and measuring the mean centered values of the ratio spectra at 266 nm for FOF and BUD. The derivative ratio spectra method is based on the measurement of analytical signals at 290, and 304 nm for FOF and at 262, and 270 nm for BUD in the first derivative of ratio spectra. Instrumental parameters and divisors concentration were carefully studied; moreover the methods have been validated as per ICH guidelines. Linearity of the two methods was obeyed in the concentration range 0.1–10 μg/mL for FOF and 3.6–36 μg/mL For BUD. Detection limit was found to be 0.058, 0.062 μg/mL for FOF and 0.33, 0.23 μg/mL of BUD for mean centering of ratio and first derivative of ratio spectra methods, respectively. The recommended procedures were successfully applied for the determination of FOF and BUD in Symbicort® turbuhaler and the results demonstrated that the suggested methods are reliable and suitable for routine use with short time analysis. The results were statistically analyzed and confirmed accuracy and precision.

UV SPECTROPHOTOMETRIC METHODS FOR THE SIMULTANEOUS DETERMINATION OF AMOXICILLIN AND FLUCLOXACILLIN.

Spectrophotometric methods were introduced for the simultaneous determination of Amoxicillin (AMX) and flucloxacillin(FLX) in their pure forms and capsules pharmaceutical formulations. The first method was ratio difference (RD), in which the amplitude difference between 238 and 255 nm for AMX and between 254 and 238 nm for FLX were measured.The second one was mean centering of ratio spectra (MCR) in which the peak amplitude at 286nm for the determination of AMX and the peak amplitude at 236 nm for the estimation of FLX were measured. The third method was Area under the curve (AUC) where the range of 226 and 236 nm were adopted for AMX determination and of 240 and 247 nm for FLX determination. All of the previous methods were successfully used for quantitation of AMX and FLX in concentration ranges of 5-50µg/ml and 10-70µg/ml, respectively by RD and MCR methods and of 10-60µg/ml and 10-70µg/ml, respectively for AMX and FLX by AUC method. All of the developed methods were validated using ICH guidelines and statistically compared to a reported method. The adopted methods can be applied for the regular analysis of AMX and FLX mixture in QC laboratories.

DETERMINATION OF SIMULTANEOUS SULFAMETHOXAZOLE AND TRIMETHOPRIM BY ULTRAVIOLET SPECTROPHOTOMETRY WITH MEAN CENTERING OF RATIO SPECTRA

Objective: Mean centering of ratio spectra (MCR) is analysis method for determination levels of mixture that has maximum wavelength is overlapping, and without preliminary separation. The purpose of this study is a determination of sulfamethoxazole (SLF) and trimethoprim (TRM) mixture by ultraviolet spectrophotometry with MCR.Methods: Absorption spectra of each drug were recorded and divided by the corresponding concentration of divisor, and the ratio spectra were then mean centered. SLF and t TRM concentrations were determined from calibration graphs by measuring at obtained maximum wavelengths 256 nm for SLF and 288 nm for TRM.Result: The result determination of SLF and TRM content in tablet S was 103.31±0.34% and 96.588±2.13%, respectively, result of validation method was fulfilled, percentage recovery for SLF was 101.24% and relative standard deviation (RSD) was 0.41%, and percentage recovery for TRM was 100.89% and RSD was 0.96%.Conclusion: The determination simultaneous by ultraviolet spectrophotometry of MCR was found to be accurate, precise, simple, and rapid method and can be used for SLF and TRM mixture.

Development and validation of different spectrophotometric and chromatographic methods for determination of clotrimazole and hydrocortisone in a topical cream

In this study, we developed and validated different spectrophotometric and chromatographic methods for determination of clotrimazole (CLO) and hydrocortisone (HDC) in their combined dosage form. The developed spectrophotometric methods were first derivative spectrophotometry ( 1 D) by measuring the peak amplitude at 247.4 and 236.2 nm for CLO and HDC, respectively, second derivative of ratio spectra ( 2 DD) at 225.4 nm for CLO and 269 nm for HDC, dual wavelength spectrophotometry (DW) by measuring absorbance difference between 225.4 and 264 nm for CLO and between 228 and 247 nm for HDC determination, advanced absorbance subtraction method (AAS) between 225.4 and 264 nm and mean centering of ratio spectra (MCR) spectrophotometric method in the range of 232-265 nm. On the other hand, the proposed chromatographic method was Ultra Performance Liquid Chromatography method (UPLC) using acetonitrile:water (50:50, v : v ) as a mobile phase and the peaks were detected at 228 nm. All these methods were successfully applied to determine the two studied drugs in pure forms; laboratory prepared mixtures and combined dosage form. Methods validations were carried out regarding linearity, accuracy, precision and selectivity. The spectrophotometric methods exhibited a linear dynamic range over 5-40 and 5-45 µg/mL for CLO and HDC, respectively, and over 3-35 and 5-50 µg/mL for UPLC method. Sensitive and selective spectrophotometric and UPLC methods for the determination of clotrimazole and hydrocortisone in their topical formulation were successfully developed and validated. The developed methods were statistically confirmed to be accurate, precise and reproducible.

Innovative spectrophotometric methods for simultaneous estimation of the novel two-drug combination: Sacubitril/Valsartan through two manipulation approaches and a comparative statistical study

Different innovative spectrophotometric methods were introduced for the first time for simultaneous quantification of sacubitril/valsartan in their binary mixture and in their combined dosage form without prior separation through two manipulation approaches. These approaches were developed and based either on two wavelength selection in zero-order absorption spectra namely; dual wavelength method (DWL) at 226nm and 275nm for valsartan, induced dual wavelength method (IDW) at 226nm and 254nm for sacubitril and advanced absorbance subtraction (AAS) based on their iso-absorptive point at 246nm (λiso) and 261nm (sacubitril shows equal absorbance values at the two selected wavelengths) or on ratio spectra using their normalized spectra namely; ratio difference spectrophotometric method (RD) at 225nm and 264nm for both of them in their ratio spectra, first derivative of ratio spectra (DR1) at 232nm for valsartan and 239nm for sacubitril and mean centering of ratio spectra (MCR) at 260nm for both of them. Both sacubitril and valsartan showed linearity upon application of these methods in the range of 2.5–25.0μg/mL. The developed spectrophotmetric methods were successfully applied to the analysis of their combined tablet dosage form ENTRESTO™. The adopted spectrophotometric methods were also validated according to ICH guidelines. The results obtained from the proposed methods were statistically compared to a reported HPLC method using Student t-test, F-test and a comparative study was also developed with one-way ANOVA, showing no statistical difference in accordance to precision and accuracy.

Development and Validation of Eco-Friendly Liquid Chromatographic and Spectrophotometric Methods for Simultaneous Determination of Coformulated Drugs: Phenylephrine Hydrochloride and Prednisolone Acetate.

Five simple, sensitive, and eco-friendly LC and UV spectrophotometric methods have been developed for the simultaneous determination of phenylephrine hydrochloride (PHE) and prednisolone acetate (PRD) in their combined dosage form. The first method was reversed-phase (RP) LC using methanol-water-heptane-1-sulfonic acid sodium salt (75 + 25 + 0.1, v/v/w) as a mobile phase. Separation was achieved using an XSelect HSS reversed-phase C18 analytical column (250 × 4.6 mm, 5µm). The flow rate was 1.0 mL/min and UV detection was done at 230 nm. Quantification was achieved over the concentration ranges of 5-50 µg/mL for PHE and 2-90 µg/mL for PRD. Four spectrophotometric methods were proposed, namely dual wavelength, first derivative of ratio spectra, ratio difference, and mean-centering of ratio spectra. Linearity was observed in the concentration ranges of 10-120 and 5-35 µg/mL for PHE and PRD, respectively, for the spectrophotometric methods. Green solvents were used in the proposed methods because they play a vital role in the analytical methods' influence on the environment. The suggested methods were validated regarding linearity, accuracy, and precision according to the International Conference on Harmonization guidelines, with satisfactory results. These methods could be used as harmless substitutes for routine analysis of the mentioned drugs, with no interference from excipients.

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.

Different spectrophotometric and TLC-densitometric methods for determination of pyrazinamide in presence of its impurity

In this search, three selective spectrophotometric and TLC-densitometric methods have been developed and validated for quantitative determination of Pyrazinamide (PYN) and its impurity, Pyrazine-2-carboxylic acid (PYA). The proposed methods are third derivative spectrophotometric (Method I), first derivative of ratio spectra spectrophotometric (Method II), mean centering of ratio spectra spectrophotometric (MCR) (Method III) and TLC-densitometric (Method IV). In method (I); 3D amplitudes at 276.2 and 274.6nm were measured and used for determination of PYN and PYA, respectively. In method (II); PYN was determined by measuring the 1DD peak amplitude at 225.8nm using 30µgmL−1 of PYA as a divisor; on the other hand PYA was determined by measuring this amplitude at 245.2nm using 18µgmL−1 of PYN as a divisor. For method (III); the amplitudes of the mean centered ratio spectra at 268.4 and 268.8nm were used for PYN and PYA, respectively. On the other hand, the forth method is TLC-densitometric method at which the chromatographic separation was achieved using silica gel 60F254 TLC plates and mixture of methylene chloride: methanol: ammonia solution (7:3:0.1, by volume) as a developing system followed by UV-scanning at 275nm.The proposed methods were successfully applied for determination of the PYN in its pharmaceutical formulation. Also they were statistically compared with the reported method using student’s-t and F-tests and there was no significant difference between them regarding both accuracy and precision.

Stability Indicating Spectrophotometric Methods for Determination of Ivabradine Hydrochloride in the Presence of Its Degradation Product

Five simple, specific, accurate and precise stability indicating spectrophotometric methods have been developed for determination of Ivabradine HCl (Iva) in the presence of its acid degradate, in bulk powder and in pharmaceutical formulations. Forced degradation was performed using 2N HCl. The degradation product was identified by infrared spectroscopy and mass spectrometry, and the pathway of degradation was illustrated. The first method is a second derivative (D2) spectrophotometric method, which allows the determination of Iva in presence of its degradate at 290 nm. The second method is the first derivative of the ratio spectra (1DD) by measuring the peak amplitude at 294 nm. The third method is the ratio difference (RD) method which depends on measuring the difference between the amplitudes of the ratio spectra at 249 nm and 298 nm. The fourth method is the constant center (CC) method where the original spectra of Iva were obtained. The fifth method is mean centering of ratio spectra (MCR). The proposed methods were validated according to ICH guidelines. The obtained results were statistically compared with those of a reported HPLC method. The comparison showed that there is no significant difference between the proposed methods and the reported method regarding both accuracy and precision.

Different Mathematical Processing of the Ratio Spectra for Quantification of Cefaclor in Presence of its Acid Induced Degradation Product

Three simple mathematical spectrophotometric methods based on processing the ratio spectra were developed and validated for determination of cefaclor in presence of its acid induced degradation product; namely First derivative of ratio spectra (1DD) Method (A), Ratio subtraction method (RS) Method (B) and Mean centering of ratio spectra (MCR) Method (C). The accuracy, precision and linearity ranges of the proposed methods were determined. The methods were validated and the specificity was assessed by analyzing synthetic mixtures containing the drug and its degradate. The three methods were applied for the determination of the cited drug in its pharmaceutical preparation and the obtained results were statistically compared with those of a reported method. The comparison showed that there is no significant difference between the proposed methods and the reported method regarding both accuracy and precision.

Comparative Study of the Spectral Resolution Efficiency of the Recently Developed and Conventional Spectrophotometric Methods in the Analysis of Severely Overlapped Zero-Order Absorption Spectra with the Same Geometrical Features

Simple, cost-effective, safe, accurate, precise and environmentally friendly spectro-photometric methods were developed and validated for the quantitative determination of valaciclovir (VAL) in the presence of its related impurity in bulk powder and in its pharmaceutical preparation. This related impurity namely guanine (GUA) is the potential and synthesis impurity of VAL. The spectra of VAL and GUA show the same geometrical features with different absorptivities, so their resolution is very challengeable. A Comparative study was conducted for the results of the conventional methods namely, dual wavelength (DW), first derivative of ratio spectra (1DD) and mean centering of ratio spectra (MCR) versus the recently developed methods namely, induced dual wavelength (IDW), ratio difference (RD) and constant center (CC). The optimized methods allow the estimation of VAL in the concentration range 5-50 μg/mL. The methods were validated as per ICH guidelines and the specificity was assessed by analyzing synthetic mixtures containing different percentages of the related impurity with the drug. The obtained results were compared with that of the official HPLC method by using one-way analysis of variance (ANOVA) and proved to be suitable for quality control laboratories.

Spectrofluorimetric Determination of Beryllium by Mean Centering of Ratio Spectra.

Trace amounts of beryllium has been determined by spectrofluorimetric method that used morin as fluorimetric reagent. Beryllium gives a highly fluorescent complex with morin. The excitation wavelength of morin and Be-morin complex were 410 and 430. The fluorescence spectra of morin and Be-morin complex were overlaped in excitation wavelength of 430nm. A method based on mean centering of ratio spectra has been performed to remove the interference caused by morin as it overlaps with the Be-morin spectra. The linear range of beryllium concentration is in 0.2-200ppb range. The parameters of detection limit and RSD were 0.18ppb and 4.6% respectively. This method was used for determination of beryllium in copper-beryllium alloy as a real sample. In determination of Be(II), the interference by Cu(II) was very serious, which was eliminated by adding triethanolamine.