Ratio Spectra Derivative Method Research Articles

Utilizing two different sustainable and green spectrophotometric approaches using derivative ratio spectra for the determination of a ternary severely overlapped mixture: application to veterinary formulation

Mathematical manipulation technique has proven to be a very powerful tool for efficient processing and handling of highly overlapped spectra. This work introduced two green and sustainable approaches for the successful recovery of the ternary mixture, Tylosin tartarate (TYL), Sulfadimdine (SLD), and Trimethoprim (TRI). The approaches were constructed using three different methods, derivative ratio spectrum zero-crossing method (DRSZ), double divisor ratio spectra derivative method (DDRD), and factorized derivative ratio method coupled with spectrum subtraction (FDRM-SS). The two approaches succeeded in recovering the three drugs (Linearity range achieved were 0.5–5 µg/mL for TYL, 0.3–1.3 µg/mL for SLD, and 0.3–5 µg/mL for TRI), giving convenient standard deviations and satisfactory recovery percentages. The recommended methods have been verified in accordance with (ICH) guidelines. When the results were statistically compared to the official methods, no significant difference was found. Both AGREE—Analytical GREEnness Metric Approach and Software, and White Analytical Chemistry (WAC) RGB model gave scores of 0.93 and 97.2%, respectively, which proved that the approaches were eco-friendly and abiding by the sustainability principles.

Simultaneously Estimation of Multicomponent Containing Formulation by using UV-Spectroscopy [Aspirin-Atorvastatin

The market is currently offering a wide range of combination dose forms, and the quantity is growing daily. Due to their improved potency, various actions, speedier relief, fewer side effects, and higher patient acceptability, these multicomponent formulations are becoming more and more popular. It is therefore intended that these formulations satisfy all requirements for their efficacy, safety, and quality. This is only feasible if many analytical methods are available to determine them. When doing a simultaneous multicomponent analysis, various UV spectrophotometric techniques are applied.These techniques rely on logging and processing absorption spectra computationally. The various techniques covered in this review include the use of simultaneous equations, derivative spectrophotometry, mean centring of the ratio spectra, absorption factor method, double divisor ratio spectra derivative method, successive ratio derivative spectra, Q-absorbance ratio method, isosbestic point method, absorpitivity factor method, dual wavelength method, mean centring of the ratio spectra, and multivariate methods. A synopsis of the theories and a few uses for these techniques are given.

A new selective colorimetric method coupled with a high-resolution UV method for the consecutive quantification of three drugs in semi-solid preparations

Triderm® cream and ointment contain clotrimazole (CLO), betamethasone dipropionate (BET), and the poor UV absorbing gentamycin (GEN), in addition to the preservative benzyl alcohol (BEN) which exists only in a cream preparation. A green, selective colorimetric approach was elaborated to increase the sensitivity of GEN quantification in Triderm® preparations, which depends on the immediate formation of a pink ion-pair between GEN and erythrosine (ERY) reagent in an aqueous acidic medium. The ion pair was made soluble in water with the assistance of the surfactant agent poloxamer 188 which is presented in this manuscript as an efficient solubilizing agent for the hydrophobic ion-pair. This surfactant agent has the feature of not affecting the native color of ERY, additionally the ease of preparing its aqueous solution with no need for heating or long waiting. The resulting complex GEN-ERY was measured directly at 545nm. This colorimetric approach was coupled with the Unlimited Derivative Ratio (UDD), which is a new smart UV method employed for the concurrent quantification of BET and CLO in Triderm® preparations without any intervention from BEN, due to its capability to resolve an extremely overlapped ternary spectrum that has no extended part, iso-absorptive point or robust zero crossing point. The newly developed UDD method depends on filtrating and measuring the signal of BET and CLO through calculating the equality factor(F) for CLO and BET after dividing their spectrum by BEN spectrum, derivatizing the resulting ratio spectrum, then constructing a regression equation employing the F factor for each BET and CLO. The overlapping excipient BEN was quantified via the Double Divisor Ratio spectra derivative method (DDR) relying on using a divisor comprising of a mix of BET + CLO. The advanced spectrophotometric approach validity was checked by confirming the linearity, accuracy, precision, and specificity in accordance with the ICH directions. NO notable difference when statistically comparing the newly established approach to the reference approach.

NOVEL SPECTROPHOTOMETRIC METHOD DEVELOPMENT AND VALIDATION FOR SIMULTANEOUS ESTIMATION OF ABACAVIR SULPHATE, LAMIVUDINE AND DOLUTEGRAVIR SODIUM IN DOSAGE FORM

Double Divisor ratio spectra derivative method was developed and validated for a ternary mixture containing abacavir sulphate (ABA), lamivudine (LAM) and dolutegravir sodium (DOL) in distilled water. The method is based on dividing the absorption spectra of ternary mixture by the sum of absorption spectra of two of the three components and then taking the first derivative of the ratio spectra. The linear range was found to be 5 – 40 µg mL-1 for ABA, 4 – 20 µg mL-1 for LAM and 1 - 20 µg mL-1 for DOL. The mean % recoveries were found to be in the range of 98.85 – 100.93 % for ABA, 99.65 – 99.38 % for LAM and 100.29 – 98.67 % for DOL. ICH guidelines were used to validate the developed method. The proposed method can be successfully applied to pharmaceutical formulations as it is rapid, simple, sensitive, selective and accurate.

Simultaneous spectrophotometric determination of finasteride and tadalafil in recently FDA approved Entadfi™ capsules

Entadfi™ is a recently FDA approved pharmaceutical combination capsule of finasteride and tadalafil. It was prescribed for the treatment of urinary tract disorders caused by benign prostatic hyperplasia in men. This paper introduced the first spectrophotometric methods for simultaneous determination of finasteride and tadalafil in the pure form and in the pharmaceutical capsules. UV absorption spectra of finasteride and tadalafil exhibited overlap hindered the direct simultaneous determination of the cited drugs. The UV absorption spectra of finasteride and tadalafil were transformed to the second order derivative. Finasteride could be determined selectively at 230.80 nm without interference from tadalafil. Moreover, tadalafil could be determined selectively at 292 nm without interference from finasteride. The ratio spectra of the studied drugs were derived and the derived ratio spectra of each drug were transformed to the first order derivative. Finasteride could be determined selectively at 218.80 nm without interference from tadalafil. Moreover, tadalafil could be determined selectively at 289.60 nm without interference from finasteride. The methods showed linearity with an excellent correlation coefficient in the concentration range of 10–140 µg/mL for finasteride and 3–40 µg/mL for tadalafil. The methods were validated following ICH guidelines for accuracy, precision, robustness, limit of detection, limit of quantification, and selectivity. The methods were found to be sensitive with LOD values for finasteride and tadalafil of 2.406 µg/mL and 0.876 µg/mL using the second derivative with zero crossing method and 2.229 µg/mL and 0.815 µg/mL using the first derivative of ratio spectra method. The methods were successfully applied for the determination of the studied drugs in their laboratory prepared mixtures, with mean percent recovery for finasteride and tadalafil of 99.37% and 99.17% using the second derivative with zero crossing method and 99.74% and 99.56% using the first derivative of ratio spectra method. Furthermore, the described methods were successfully applied for determination of the studied drugs in Entadfi™ capsules without interference from excipients. Based on the proposed results, the described methods could be utilized as simple method for the quality control of the studied drugs.

APPLICATION OF TWO ADVANCED DERIVATIVE SPECTROPHOTOMETRIC METHODS FOR SIMULTANEOUS ESTIMATION OF SALBUTAMOL SULPHATE, AMBROXOL HYDROCHLORIDE AND THEOPHYLLINE IN PURE AND COMMERCIAL FORMULATIONS

Objective: Two advanced spectrophotometric methods have been proposed for the simultaneous determination of Salbutamol sulphate, Ambroxol hydrochloride and Theophylline in pure and pharmaceutical formulations. The proposed methods exclude the hectic steps of time-consuming sample preparations or purification or separation steps. There is no any spectrophotometric method has been avail for simultaneous estimation of the ternary mixture containing Salbutamol sulphate, Ambroxol hydrochloride and Theophylline.
 Methods: The methods are derivative ratio spectra zero-crossing method and double divisor ratio spectra derivative method respectively. Both the methods are found to be rapid, accurate, precise, reliable and economical as well. The developed methods show best results in terms of linearity, accuracy, precision, limit of detection and limit of quantification for standard laboratory mixtures of pure drugs and marketed formulations.
 Results: The range for Salbutamol sulphate, Ambroxol hydrochloride and Theophyllineare found to be 1-35 µg ml-1, 5-35 µg ml-1and 6-60 µg ml-1 respectively. For the derivative ratio spectra zero-crossing method, the values of the limit of detection are found to be 0.3161 µg ml-1, 0.2212 µg ml-1 and 0.2910 µg ml-1 and the values limit of quantification are found to be 0.9571 µg ml-1, 0.7412 µg ml-1 and 0.9671 µg ml-1 for Salbutamol sulphate, Ambroxol hydrochloride and Theophylline respectively. For double divisor ratio spectra derivative method, limit of detection values is found to be 0.3251 µg ml-1, 0.2591 µg ml-1 and 0.2640 µg ml-1 and the limit of quantification values are found to be 0.9870 µg ml-1, 0.8650 µg ml-1 and 0.8812 µg ml-1 for Salbutamol sulphate, Ambroxol hydrochloride and Theophylline respectively.
 Conclusion: The common excipients and additives did not interfere in the determinations of any of the drugs while being analysed for commercial formulations. These two spectrophotometric methods, which determine SS, AH, and THE simultaneously, are simple, specific, accurate, precise, rapidly, and economically, indicating that they can be used routinely in pharmaceutical analysis. As a result, derivative spectrophotometry may be used effectively for the simultaneous determination of SS, AH and THE in the combined dosage forms without any prior separation of individual drugs.

Resolving Problems Encountered in Spectrophotometric Analysis of a Ternary Mixture of Linagliptin, Empagliflozin, and Metformin Hydrochloride

There are two main problems encountered in spectrophotometric analysis of a ternary mixture composed of linagliptin LINA, empagliflozin EMPA and metformin hydrochloride MET. The first problem is due to the severe overlap in their zero and derivative spectra. To overcome this problem, LINA was determined by direct spectrophotometry at λ max = 298 nm where there is no interference from other components while, EMPA and MET were determined using double divisor ratio spectra derivative method DDRD. In this method, the first derivative spectra were calculated for ratio spectra generated by dividing the absorption spectra of ternary mixtures containing increasing concentrations of one of the components by a standard spectrum of binary mixture of the other two components (double divisor). The calibration graphs were constructed by measuring the amplitude at either the minimum or maximum wavelengths against the concentrations. The selected wavelengths for determination of EMPA and MET are 282.92 and 250 nm, respectively. The second problem arises from the presence of LINA and EMPA as minor components in their recently approved dosage form with MET thus, sample enrichment through spiking was employed for LINA and EMPA to enable their spectrophotometric analysis in laboratory prepared mixtures that have the same ratio of the three components as in their pharmaceutical dosage form.

Smart spectrophotometric methods for stability assessment of two co-formulated antigout drugs

Simple, sensitive and accurate stability indicating spectrophotometric methods have been developed for the simultaneous determination of probenecid, colchicine as well as colchicine degradation product in their ternary mixture. Probenecid was firstly assayed using the double divisor ratio spectra derivative method. On the other hand, three spectrophotometric methods, namely: ratio difference, derivative ratio and mean centering of ratio spectra, have been suggested for the simultaneous quantification of colchicine and its degradation product. The obtained calibration curves were linear at 2.5–30.0 μg/mL, 0.5–25.0 μg/mL and 1.0–13.0 μg/mL for probenecid, colchicine and colchicine degradation product, respectively. The investigated methods were validated in accordance with the International Council for Harmonisation guidelines and were effectively used for quantification of probenecid and colchicine in their bulk powders and combined pharmaceutical dosage form.

Quantitative Analysis of Two Pharmaceutical Combinations Containing Amlodipine with Either Bisoprolol or Candesartan Using Different UV Spectrophotometric Methods.

Two fixed-dose combination tablets of amlodipine (AML) with bisoprolol (BIS) and amlodipine with candesartan (CAN) were recently approved for the treatment of hypertension. Three UV spectrophotometric analytical methods were developed for the estimation of the above drugs in their combination mixtures. For the AML and BIS mixture, AML was quantified directly by a zero-order spectrophotometric method at 360 nm without interference from BIS, whereas BIS was quantified by the ratio difference (RD) spectrophotometric method by calculating the difference between the amplitude values of the ratio spectra at 226 and 215 nm. For the AML and CAN mixture, AML was quantified directly by a zero-order spectrophotometric method at 360 nm without interference from CAN, whereas CAN was quantified by the first derivative of ratio spectra method by measuring the amplitude values of the derived spectra at 259 nm.BIS). The proposed methods were successfully applied for quantitative analysis of AML with BIS and AML with CAN in their synthetic laboratory-prepared mixtures and pharmaceutical tablets with acceptable results in terms of accuracy and precision. Simple, accurate, and environmentally friendly spectrophotometric methods were described for selective determination of the investigated drugs in their fixed-dose combinations.

A Double Divisor Ratio-Spectra Derivative Method for the Ternary Mixture of Aspirin, Clopidogrel Bisulphate and Rosuvastatin Calcium

Quantitative analysis of formulation containing Aspirin, Clopidogrel Bisulphate and Rosuvastatin Calcium were performed using double divisor ratio spectra derivative method. Detection wavelength for Aspirin, Clopidogrel Bisulphate and Rosuvastatin Calcium was 240.2 nm, 231.8 nm and 263.2 nm respectively. The linearity range for all three drugs was 2-20 μg/mL and it was validated through regression analysis and residual analysis. Mean percentage recovery was 100.09 %, 100.60 % and 99.86 % for Aspirin, Clopidogrel Bisulphate and Rosuvastatin Calcium respectively. The developed method was validated according to International Council for Harmonization guidelines and validation approach is much more justified than the usual approach. The use of advanced statistical tools for validation ensures the efficiency; quality and reproducibility of our method. Obtained results were satisfactory and ensured the quality and reproducibility of the method.

UV Spectrophotometric Methods to Quantify Alogliptin Benzoate and Pioglitazone Hydrochloride

Three new, precise, accurate and sensitive UV-Spectrophotometric methods namely Ratio Difference Spectroscopic Method (RDSM), First Derivative of Ratio Spectra Method (DR1) and Area Under Curve Method (AUC) were developed and validated for simultaneous assessment of alogliptin benzoate (ALO) and pioglitazone hydrochloride (PIO) in tablet dosage form. In RDSM, ratio spectra of both the drugs were recorded by dividing the mixtures using interfering drug as divisor. Then the difference between the amplitudes of obtained ratio spectra was measured at 288 and 291 nm for ALO and 236 and 245 nm for PIO. The second method DR1, where the first derivative of ratio spectra of both the drugs were recorded and the first derivative signal was measured at 290 nm for ALO and 276.8 nm for PIO. The scaling factor was fixed as 1 and wavelength interval (Δλ) as 2 for recording the first derivative of ratio spectra. In the third method (AUC), peak area of recorded zero order spectra was measured at 276 ± 10 nm for ALO and 267.8 ± 10 nm for PIO. All three proposed methods were validated according to “International Conference on Harmonization” (ICH) guidelines parameters. For all three methods, ALO and PIO obeyed Beer’s law in the range of 0.5-5 & 1.8-18 µg/ml, respectively. The % RSD of repeatability of measurement, intra-day and inter-day precision were found to be less than 2 for all three methods. Limit of detection (LOD) and Limit of quantification (LOQ) of the drugs were calculated which proved the sensitivity of the methods. The accuracy ranged between 98-101% for all three methods. No interference from pharmaceutical excipients present in the formulation was observed. These proposed methods were found to be simple, sensitive, accurate and precise and can be applied to the simultaneous estimation of ALO and PIO in combined tablet formulation and also appropriate for routine quality control analysis.

UV-spectrophotometry-assisted chemometric methods for simultaneous determination of ambroxol hydrochloride and doxofylline in pharmaceutical formulation

Two methods, ratio spectra derivative method and partial least squares regression (PLS) were developed for the simultaneous estimation of ambroxol hydrochloride and doxofylline in combined dosage form. In the first method, ratio spectra derivative method, analytical signals were measured at the wavelengths corresponding to either maximums or minimums for both drugs in the first derivative spectra of the ratio spectra obtained by dividing the standard spectrum of one of two drugs in water. Partial least squares regression (PLS) was used for data analysis of and the parameters of the chemometry procedures were optimized. In this study, the simultaneous determination of ambroxol hydrochloride and doxofylline in pharmaceuticals by chemometric approaches using UV spectrophotometry has been reported. Spectra of ABH and DOX were recorded at several concentrations within their linear ranges between 2-12 μg/mL and 15-40 μg/mL respectively and applied to pharmaceutical formulation, tablet, with no interference with excipients as indicated by the results of the recovery study. The proposed methods are simple, rapid and can be easily used in the quality control of drugs as alternative analytical tools.

Immobilized Nano-TiO2 Photocatalysts for the Degradation of Three Organic Dyes in Single and Multi-Dye Solutions

Heterogeneous photocatalysis with titanium dioxide (TiO2) is considered one of the most promising Advanced Oxidation Processes (AOPs). In order to solve issues related to catalyst recovery and possible agglomeration, which are typical of catalysts in nanoparticle form, self-organized nanotubular TiO2 films directly immobilized on a metal substrate can be produced through anodization. In this study, a nanotubular anodic oxide was tested in the degradation of three organic dyes, namely Direct Red 80, Methylene Blue, and Rhodamine B, in single, binary, and ternary mixtures, to simulate industrial effluents with the co-presence of multiple dyes. To better understand the dyes’ behavior and possible interaction effects, spectrophotometry was used to analyze the degradation of each dye in the mixture. The zero-crossing first-order derivative approach and double divisor ratio spectra derivative method were used for the analysis of binary and ternary mixtures, respectively, to overcome quantification problems due to spectra overlapping. The photocatalytic system demonstrated good efficiency, supporting the use of nanotubular TiO2 as a photocatalyst for dye mixtures. Moreover, the interaction among dyes can actually affect, both positively and negatively, photodegradation kinetics, posing an issue in understanding the actual efficiency of the purification process as a function of the effluent composition.

Simultaneous Determination of Hydrochlorothiazide in Combination with Some Antihypertensive Drugs in The Presence of Its Main Impurities in Pure Form and Pharmaceutical Formulations

Background:Hydrochlorothiazide (HCTZ) is potent diuretic that is used alone or in combination with other drugs such as labetalol (Lab) (mixtures Ι) or nebivolol (Neb) (mixtures ΙΙ) to control moderate to sever hypertension.Introduction:This paper demonstrates the establishment of different validated spectrophotometric and chemometric methods for simultaneous estimation of these mixtures in pure form and pharmaceutical formulations in the presence of HCTZ related impurities in quality control laboratories.Methods:(A) Derivative method (D3) of Lab and HCTZ and its related impurities at 245.3nm and 278.5nm respectively, (D1) of Neb and HCTZ at 294.2nm and 282.2nm, respectively. (B) First derivative of ratio spectra method (DD 1) of Lab at 244.3nm, HCTZ at 261.2nm and 275.4nm, while at 294nm for Neb and 269.4nm for HCTZ. (C) Ratio difference method which depends on measuring the distinction between the amplitudes of ratio spectra at 240nm and 288.3nm for Lab and at 270.1nm and 277.4nm for HCTZ for mixture Ι while at 290.4nm and 299.2nm for Neb and at 232.2nm and 254nm for HCTZ for mixture ΙΙ. (D) Mean centering of ratio spectra (MC) and (E) partial least squares regression (PLS) and principal component regression (PCR).Results:These methods were applied over concentration ranges of 10-100 µg/ml, 10-75 µg/ml and 2.5- 25 µg/ml of Lab, Neb and HCTZ, respectively. Methods were validated according to ICH guidelines and statistical comparison of results of reported and proposed methods revealed no difference.Conclusion:The methods were successfully used for the frequent analysis of selected mixtures in quality control laboratories.

Spectrophotometric assessment of the brand new antiviral combination: Sofosbuvir and velpatasvir in their pure forms and pharmaceutical formulation.

Sofosbuvir (SOF) and velpatasvir (VEL) are recently co-formulated together for the treatment of hepatitis C virus. Smart and robust spectrophotometric methods were first developed and validated for quantification of SOF and VEL in their pure forms and in their combined pharmaceutical formulation without preliminary separation. VEL has two UV maxima at 302.5 and 337.0 nm that allow its direct determination by zero-order spectrophotometric method (D°) without any interference from SOF in a linear range of 2.0-30.0 μg/mL. On the other hand, determination of SOF in presence of VEL was carried out by four smart spectrophotometric methods, developed for resolving the overlaid spectra of these binary mixture. These methods are dual wavelength (DW), ratio subtraction (RS), ratio difference (RD) and first derivative of ratio spectra method (1DD). Linearity was checked and found to be in the range of 5.0-90.0 μg/mL for SOF by all of the aforementioned spectrophotometric methods. The developed methods were optimized and validated in accordance to the ICH guidelines. They were successfully utilized for estimating both SOF and VEL in their pure forms, laboratory prepared mixtures and in their pharmaceutical formulations with good recoveries. The methods can be easily applied for the routine analysis in quality control laboratories.

DERIVATIVE UV SPECTROSCOPIC APPROACHES IN MULTICOMPONENT ANALYSIS–A REVIEW

The spectrophotometric multi-component analysis involves spectrum recording and mathematical equations. However, spectral interference poses a major limitation when mixture samples are encountered. To overcome this derivative spectrophotometry (DS) has been introduced for the resolution of overlapping peaks.
 In this review modified methods like derivative quotient spectra, double divisor ratio spectra derivative method, double divisor means centering of ratio spectra method, derivative subtraction coupled with the constant multiplication method (DS-CM), amplitude subtraction (AS), modified amplitude subtraction (MAS), amplitude factor method (P-Factor), amplitude modulation method (AM), amplitude summation method (A-Sum), simultaneous derivative ratio spectrophotometry (S1DD), derivative compensation ratio via regression equation, differential dual wavelength (D1 DWL), differential derivative ratio (D1DR), successive derivative subtraction method (SDS) and derivative transformation (DT) of derivative spectrophotometry theories and applications are reviewed.
 These methods were applied to solve different complex pharmaceuticals mixtures. These developed methods were simple and cost-effective.

Spectrophotometric Methods for Simultaneous Determination of Oxytetracycline HCl and Flunixin Meglumine in Their Veterinary Pharmaceutical Formulation.

Four precise, accurate, selective, and sensitive UV-spectrophotometric methods were developed and validated for the simultaneous determination of a binary mixture of Oxytetracycline HCl (OXY) and Flunixin Meglumine (FLU). The first method, dual wavelength (DW), depends on measuring the difference in absorbance (ΔA 273.4–327 nm) for the determination of OXY where FLU is zero while FLU is determined at ΔA 251.7–275.7 nm. The second method, first-derivative spectrophotometric method (1D), depends on measuring the peak amplitude of the first derivative selectively at 377 and 266.7 nm for the determination of OXY and FLU, respectively. The third method, ratio difference method, depends on the difference in amplitudes of the ratio spectra at ΔP 286.5–324.8 nm and ΔP 249.6–286.3 nm for the determination of OXY and FLU, respectively. The fourth method, first derivative of ratio spectra method (1DD), depends on measuring the amplitude peak to peak of the first derivative of ratio spectra at 296.7 to 369 nm and 259.1 to 304.7 nm for the determination of OXY and FLU, respectively. Different factors affecting the applied spectrophotometric methods were studied. The proposed methods were validated according to ICH guidelines. Satisfactory results were obtained for determination of both drugs in laboratory prepared mixture and pharmaceutical dosage form. The developed methods are compared favourably with the official ones.

Investigation of different spectrophotometric and chemometric methods for determination of entacapone, levodopa and carbidopa in ternary mixture

New, simple, accurate and sensitive UV spectrophotometric and chemometric methods have been developed and validated for determination of Entacapone (ENT), Levodopa (LD) and Carbidopa (CD) in ternary mixture. Method A is a derivative ratio spectra zero-crossing spectrophotometric method which allows the determination of ENT in the presence of both LD and CD by measuring the peak amplitude at 249.9nm in the range of 1–20μgmL−1. Method B is a double divisor-first derivative of ratio spectra method, used for determination of ENT, LD and CD at 245, 239 and 293nm, respectively. Method C is a mean centering of ratio spectra which allows their determination at 241, 241.6 and 257.1nm, respectively. Methods B and C could successfully determine the studied drugs in concentration ranges of 1–20μgmL−1 for ENT and 10–90μgmL−1 for both LD and CD. Methods D and E are principal component regression and partial least-squares, respectively, used for the simultaneous determination of the studied drugs by using seventeen mixtures as calibration set and eight mixtures as validation set. The developed methods have the advantage of simultaneous determination of the cited components without any pre-treatment. All the results were statistically compared with the reported methods, where no significant difference was observed. The developed methods were satisfactorily applied to the analysis of the investigated drugs in their pure form and in pharmaceutical dosage forms.

Comparative study between recent methods manipulating ratio spectra and classical methods based on two-wavelength selection for the determination of binary mixture of antazoline hydrochloride and tetryzoline hydrochloride

A comparative study was developed between two classical spectrophotometric methods (dual wavelength method and Vierordt's method) and two recent methods manipulating ratio spectra (ratio difference method and first derivative of ratio spectra method) for simultaneous determination of Antazoline hydrochloride (AN) and Tetryzoline hydrochloride (TZ) in their combined pharmaceutical formulation and in the presence of benzalkonium chloride as a preservative without preliminary separation. The dual wavelength method depends on choosing two wavelengths for each drug in a way so that the difference in absorbance at those two wavelengths is zero for the other drug. While Vierordt's method, is based upon measuring the absorbance and the absorptivity values of the two drugs at their λmax (248.0 and 219.0nm for AN and TZ, respectively), followed by substitution in the corresponding Vierordt's equation. Recent methods manipulating ratio spectra depend on either measuring the difference in amplitudes of ratio spectra between 255.5 and 269.5nm for AN and 220.0 and 273.0nm for TZ in case of ratio difference method or computing first derivative of the ratio spectra for each drug then measuring the peak amplitude at 250.0nm for AN and at 224.0nm for TZ in case of first derivative of ratio spectrophotometry. The specificity of the developed methods was investigated by analyzing different laboratory prepared mixtures of the two drugs. All methods were applied successfully for the determination of the selected drugs in their combined dosage form proving that the classical spectrophotometric methods can still be used successfully in analysis of binary mixture using minimal data manipulation rather than recent methods which require relatively more steps. Furthermore, validation of the proposed methods was performed according to ICH guidelines; accuracy, precision and repeatability are found to be within the acceptable limits. Statistical studies showed that the methods can be competitively applied in quality control laboratories.

Spectral resolution and simultaneous determination of oxymetazoline hydrochloride and sodium cromoglycate by derivative and ratio-based spectrophotometric methods

Sodium cromoglycate (SCG) and oxymetazoline hydrochloride (OXMT) are administered in combination for effective treatment of nasal congestion and allergy. In this work, SCG was determined using direct spectrophotometry by measuring its zero order absorption spectra at its λ max 320.6 nm where OXMT showed zero absorbance. On the other hand, four simple, sensitive and precise spectrophotometric methods were developed and validated for the determination of OXMT in the presence of SCG in their laboratory prepared mixtures and pharmaceutical formulation, without preliminary separation; Method A: first derivative spectrophotometric method [ 1 D], Method B: first derivative of ratio spectra method [ 1 DD], Method C: ratio difference spectrophotometric method [RDSM] and Method D: ratio subtraction method [RSM]. Ratio manipulating methods (Method B, C and D) were done using divisor of 10.00 µg/mL SCG. Linear correlation was obtained in range 4-22 µg/mL for OXMT by methods A, B and D and 6-22 µg/mL for method C. All methods were validated in compliance with the International Conference on Harmonization (ICH) guidelines and satisfactory results were obtained. No significant difference was noted between the developed methods and the official one with respect to accuracy and precision.