Multivariate Spectrophotometric Methods Research Articles

Univariate versus multivariate spectrophotometric data analysis of triamterene and xipamide; a quantitative and qualitative greenly profiled comparative study

Triamterene (TRI) and xipamide (XIP) mixture is used as a binary medication of antihypertension which is considered as a major cause of premature death worldwide. The purpose of this research is the quantitative and qualitative analysis of this binary mixture by green univariate and multivariate spectrophotometric methods. Univariate methods were zero order absorption spectra method (D0) and Fourier self-deconvolution (FSD), as TRI was directly determined by D0 at 367.0 nm in the range (2.00–10.00 µg/mL), where XIP show no interference. While XIP was determined by FSD at 261.0 nm in the range (2.00–8.00 µg/mL), where TRI show zero crossing. Multivariate methods were Partial Least Squares, Principal Component Regression, Artificial Neural Networks, and Multivariate Curve Resolution-Alternating Least Squares. A training set of 25 mixtures with different quantities of the tested components was used to construct and evaluate them, 3 latent variables were displayed using an experimental design. A set of 18 synthetic mixtures with concentrations ranging from (3.00–7.00 µg/mL) for TRI and (2.00–6.00 µg/mL) for XIP, were used to construct the calibration models. A collection of seven synthetic mixtures with various quantities was applied to build the validation models. All the proposed approaches quantitative analyses were evaluated using recoveries as a percentage, root mean square error of prediction, and standard error of prediction. Strong multivariate statistical tools were presented by these models, and they were used to analyze the combined dosage form available on the Egyptian market. The proposed techniques were evaluated in accordance with ICH recommendations, where they are capable of overcoming challenges including spectral overlaps and collinearity. When the suggested approaches and the published one were statistically compared, there was no discernible difference between them. The green analytical method index and eco-scale tools were applied for assessment of the established models greenness. The suggested techniques can be used in product testing laboratories for standard pharmaceutical analysis of the substances being studied.

A Novel, Sustainable, and Eco-Friendly Spectrophotometric and Chemometric Approach for Determination of Severely Overlapped Spectrum via Unified Regression Equation: Greenness and Whiteness Assessment.

Nebivolol and valsartan (VAL) in combination with each other successfully control blood pressure and improve hypertension patient outcomes. To develop and validate innovative, simple, and sustainable spectrophotometric methods for the simultaneous analysis of nebivolol and valsartan. The new modified difference amplitude modulation (MD-AM) method uses only unified regression equation and does not require any resolution techniques. Other different approaches were also applied for the determination of the same mixture including univariate and multivariate spectrophotometric methods. The multivariate methods were PLS and PCR, whereas the univariate methods were derivative ratio (DD1), ratio difference (RD), constant center (CC), constant center spectrum subtraction (CC-SS), constant value coupled with amplitude difference (CV-AD), advanced concentration value (ACV), and amplitude difference (AD). The proposed methods use a green solvent; thus, the environmental impact of the presented procedures was evaluated qualitatively and quantitatively using six well-known evaluation tools. All methods were applied successfully for the analysis of the studied drugs in their bulk powder, pharmaceutical dosage form Byvalson®, and in vitro release at intestinal pH (7.4) using a USP dissolution tester. Results obtained were compared statistically with the reported method and with each other using a one-way ANOVA statistical test, and no significant differences were found. All green and white analytical chemistry evaluation tools results confirm the safety, sustainability, and cost-effectiveness of the approaches, indicating that the methods are regarded green and sustainable. Results were agreeable, encouraging their applicability in quality control laboratories for dosage form and making these methods an eco-friendly substitute for the analysis of this combined dosage form and for evaluating the dissolution profile. For the first time, a severely overlapped spectrum was determined using a unified regression equation without the need of extended part or zero contribution regions by the novel method MD-AM. The proposed methods are the first study of in vitro dissolution profiling of nebivolol hydrochloride (NEB) and VAL and the first sustainable and green methods applied without compromising the analytical criteria.

Development and Validation of Analytical Methods for Simultaneous Estimation of Lercanidipine Hydrochloride and Enalapril Maleate

The fixed dose of lercanidipine hydrochloride(LH) and enalapril maleate (EM) is used to provide more effective control of hypertension. The research work was aimed at the development and validation of simple and sensitive analytical methods for their quantification from tablets. The simultaneous equation, first-order derivative, and multivariate spectrophotometric methods were developed for the simultaneous estimation of LH and EM in tablets. The simultaneous equation method involves a determination of LH and EM at 236 nm and 207 nm, respectively. First order derivative UV spectrophotometry method involves using a zero crossing point of LH at 330 nm and EM at 219 nm. Both methods were validated as per ICH Q2 (R2) guidelines and found to be accurate and precise as they exhibited <2% relative standard deviation. The limit of detection (LOD) and limit of quantitation (LOQ) for LH were found to be 0.26 μg/ml and 0.78 μg/ml respectively whereas LOD and LOQ for EM were found to be 0.41 μg/ml and 1.24 μg/ml respectively for simultaneous equation method. The LOD and LOQ for LH were found to be 0.39 μg/ml and 1.19 μg/ml respectively whereas LOD and LOQ for EM were found to be 0.31 μg/ml and 0.97μg/ml respectively for the first-order derivative method. Three Chemometric methods namely classical least square (CLS), principal component regression (PCR), and partial least square (PLS) were studied for the simultaneous determination of LH and EM in tablets using spectrophotometry. A set of 25 standard mixtures containing both drugs were prepared in the range of 5–25 μg/ml for both drugs. The analytical figure of merit (FOM) was determined for all three chemometric methods. The LOD values for LH were found to be 0.97, 0.93, and 0.94 μg/ml and 0.90,0.88, and 0.89 μg/ml for EM using CLS, PCR, and PLS modeling techniques. The proposed methods were user-friendly, rapid, and sensitive enough for the determination of LH and EM.

In Vitro Dissolution Profile of Antihypertensive Mixture: Comparison Between Multivariate Methods and Statistical and Graphical Representation of Different Univariate Spectrophotometric Data.

Triplixam® is a new antihypertensive drug combination consisting of perindopril, amlodipine, and indapamide, which have a synergistic mechanism of action in combination with each other. Comparative study of different spectrophotometric approaches used for the simultaneous determination of perindopril, indapamide, and amlodipine in bulk powder and in dosage form Triplixam. The methods include univariate and multivariate spectrophotometric methods depending on either mathematical calculation or graphical representation of data. For the univariate methods: perindopril was resolved from other components using constant multiplication followed by spectrum subtraction resolution technique, and then two base point, AUC, constant value, and concentration value (CNV) methods were applied. For both amlodipine and indapamide: constant multiplication resolution technique was used, and then constant value and CNV methods were applied. CNV depends on graphical representation of data rather than statistical data. PLS and PCR chemometric assisted spectrophotometric techniques were also applied. The proposed methods are considered a green alternative to the reported methods as the greenness of the proposed methods was evaluated qualitatively and quantitatively by four green analytical evaluation tools. The methods were applied for the analysis of the mixture in the pharmaceutical dosage form Triplixam and in vitro release at intestinal pH (7.4) using a USP dissolution tester. The proposed green analytical methods are considered to be greener than the reported methods and simpler, so they could be used as an alternative for routine analysis of the mixture in quality control laboratories for the reason of their accurate results beside minimum manipulation steps that reduced the error and time required of the analysis with no harmful effect on analyst health as well as the environment. The study was the first in vitro dissolution profiling of perindopril, amlodipine, and indapamide. The developed methods were excellent green methods without compromising the analytical criteria.

Tailoring Two Chemometric Models for Determination of Three Neuromuscular Combined Medications and Application to Spiked Human Plasma.

Prednisolone, 6-mercaptopurine, and pyridostigmine bromide are co-administered together to treat a neuromuscular autoimmune disease called myasthenia gravis. Prednisolone and 6-mercaptopurine are immunosuppressant drugs. 6-Mercaptopurine is the active form of the pro-drug azathioprine. Pyridostigmine bromide is a cholinesterase enzyme inhibitor. Curently, green characteristics are taken into account by analysts when they develop new methods. The spectra of the three compounds and plasma are highly overlapped, so this study aims to remove this overlap and determine the three components quantitatively in raw powders and spiked human plasma using green methods. Two multivariate updated chemometric models called principle component analysis and partial least-squares were developed. Three greenness assessment tools: the eco-scale, the analytical greenness metric approach, and the green analytical method index, were used to evaluate the greenness behavior of the generated models. The two models were verified in accordance with Food and Drug Administration requirements, and the results were within acceptable limits. In addition they are relatively green in accordance with the abovementioned greenness evaluation tools. The developed models succeeded in determining the proposed drugs in their tertiary combinations and spiked human plasma with satisfactory precision, accuracy, and good greenness behavior. Two ecologically evaluated, multivariate spectrophotometric methods were developed for the determination of pyridostigmine bromide, 6-mercaptopurine, and prednisolone in spiked human plasma.

Univariate versus multivariate spectrophotometric methods for the simultaneous determination of omarigliptin and two of its degradation products

Six selective spectrophotometric techniques, four univariate and two multivariate ones were developed for the determination of the antidiabetic drug omarigliptin (OMR) along with its hydrolytic and oxidative degradation products. The proposed univariate spectrophotometric methods were ratio subtraction, first derivative, derivative ratio and ratio difference. Linearities were constructed in the range of 10.0–180.0 μg mL−1 for both OMR & its hydrolytic degradation product and 10.0–110.0 μg mL−1 for the oxidative degradation one. On the other hand, partial least squares and artificial neural networks were the chosen multivariate approaches. Their linearity ranges were 20.0–60.0 μg mL−1 for OMR and 10.0–30.0 μg mL−1 for the two degradation products. All the methods were validated, effectively applied for quantification of the intact drug in its tablet formulation and favorably compared to the reported one.

Investigation of some univariate and multivariate spectrophotometric methods for concurrent estimation of Vancomycin and Ciprofloxacin in their laboratory prepared mixture and application to biological fluids

Four simple, rapid, accurate and precise spectrophotometric methods were established and validated in accordance with ICH Q2 (R1) guidelines for the simultaneous determination of Vancomycin (VNC) and Ciprofloxacin (CPR) in their raw materials, laboratory prepared mixtures and pharmaceutics. Method A depends on using first derivative spectrophotometry (D1) where VNC and CPR were resolved at 243.6 and 262.0 nm, respectively. Concerning method B, it is based on utilizing first derivative of ratio spectra (DD1) where determination was performed at the peak maxima at 244.0 nm and 258.0 nm for VNC and CPR, respectively. Two chemometric models were applied for the quantitative analysis of both drugs in their laboratory prepared mixtures, namely, partial least squares (PLS) (method C) and artificial neural network (ANN) (method D). For univariate methods linearity range for both drugs was in the range of 3–30 and 1–10 μg/mL for VNC and CPR, respectively. Multivariate calibration methods using five level, two factor calibration model for the development of 25 mixtures were also applied for the simultaneous estimation of the two drugs in their laboratory prepared mixture using spectral region from 200.0 to 300.0 nm using interval 1 nm. The suggested methods have been successfully extended to the assay of the two studied drugs in laboratory-prepared mixtures and pharmaceuticals with excellent recovery. First derivative spectrophotometry (D1) was also applied for the assay of both analytes in spiked human plasma with good recovery. No interaction with common pharmaceutical additives has been observed which indicate the selectivity of the method. The results obtained were favourably compared with those obtained applying the reported methods. The methods are validated in compliance with the ICH Q2 (R1) guidelines and the measured accuracy and precision are assessed to be within the accepted limits.

Simultaneous determination of phenazopyridine HCl and trimethoprim in presence of phenazopyridine HCl impurity by univariate and multivariate spectrophotometric methods - Quantification of phenazopyridine HCl impurity by univariate methods

Three univariate and two multivariate spectrophotometric methods were developed and subsequently validated to determine phenazopyridine HCl (PHZ) and trimethoprim (TMP) in the presence of 2,6-Diaminopyridine (2,6-DAP). The first univariate method depends on direct determination of phenazopyridine by measuring its absorbance at 412nm and performed in concentration range of 1.00-10.00μg/mL. Then the contribution of phenazopyridine is removed by dividing the mixture spectrum with PHZ divisor (5μg/mL) after that the constant is mathematically subtracted and finally the generated spectrum is multiplied with the PHZ divisor. These steps eliminate PHZ contribution and the recovered spectrum is that of TMP and 2,6-DAP only where different methods can be applied to determine TMP and 2,6-DAP through this binary mixture spectrum. The first method to determine both components depends on measuring both TMP and 2,6-DAP through their first derivative (1DD) spectra at 244.70 and 259.60nm for TMP and 2,6-DAP, respectively with concentration ranges of 4.00-24.00μg/mL TMP and 4.00-26.00μg/mL 2,6-DAP. The second method depends on application of the isoabsorptive method which was used for TMP determination at its isoabsorptive point with 2,6-DAP at 242.64nm with concentration range 1.00-20.00μg/mL for TMP. The developed univariate methods were successfully applied to determine PHZ, TMP and PHZ impurity (2,6-DAP). Two multivariate methods were applied for determination of PHZ and TMP in presence of 2,6-DAP namely, Principle Component Regression (PCR) and Partial Least Squares (PLS). The results of the two models show that simultaneous determination of PHZ and TMP in presence of PHZ impurity can be performed in the concentration ranges of 6.00-14.00μg/mL PHZ and 24.00-56.00μg/mL TMP. All the proposed methods were successfully applied to analyze PHZ and TMP in pharmaceutical formulations without interference from the dosage form additives and the results were statistically compared with the reported method.

Validated spectrophotometric methods for simultaneous determination of nebivolol hydrochloride and valsartan in their tablet

Four simple spectrophotometric methods have been developed for the simultaneous determination of nebivolol (NEB) and valsartan (VAL) in bulk and in synthetic mixture simulated to tablet dosage form. Method (I) was area under curve (AUC) which based on the measurement of area between 246 and 256 nm for VAL and 273 and 283 nm for NEB. Method (II) applied the first derivative of ratio spectra (1DD) using VAL 40.0 µg/mL as divisor for determination of NEB, the amplitude of the peak at 294.5 nm was directly proportional to NEB concentration. NEB (30.0 µg/mL) was used as divisor for determination of VAL. The amplitude of peak at 253.4 nm was directly proportional to VAL concentration. Method (III) was the ratio difference (RD) method which based on the measurement of difference in amplitudes (∆P) in the ratio spectra; ∆P (291-275) was directly proportional to NEB concentration, and ∆P (239.2-301.5) was directly proportional to VAL concentration. Calibration curves of the three methods are linear over the concentration ranges of 2.0–80.0 µg/mL and 4.0–80.0 µg/mL for NEB and VAL, respectively. The mean percentage recovery ± SD values for tablet assay for NEB and VAL, respectively were found to be 100.59 ± 1.32 and 100.55 ± 1.12 using AUC, 100.02 ± 1.52 and 101.18 ± 0.42 using 1DD method, and finally 101.38 ± 1.88 and 101.24 ± 0.28 using RD method.Method (IV) involved multivariate spectrophotometric methods including classical least squares (CLS), principal component regression (PCR), and partial least squares (PLS) applied to the UV absorption spectra of the standard solutions containing both drugs recorded in the range of 272–282 nm at 1 nm intervals. Calibration was performed using training set consisting of ten binary mixture solutions in different combinations in range of 5.0–60.0 µg/mL NEB and 15.0–80.0 µg/mL VAL. The mean percentage recovery ± SD values for tablet assay for NEB and VAL, respectively were found to be 100.69 ± 1.54 and 100.90 ± 0.55 using CLS, 100.72 ± 1.54 and 100.89 ± 0.55 using PCR, and 100.72 ± 1.54 and 100.89 ± 0.55 using PLS. The four developed methods were validated and showed successful application to the simultaneous determination of NEB and VAL in their synthetic mixtures. ICH guidelines were used to validate the methods. F and t-tests were used for statistical comparison between the results obtained by the developed methods and those of the reported one. No significant difference was observed regarding both accuracy and precision.

Univariate calibrations with or without chemometric assistance for determination of drugs lacking peak maxima in their zero-order profiles.

Trandolapril has no sharp peak in its zero-order spectrum and therefore, it is difficult to be measured by direct spectrophotometry. In this manuscript, several univariate and multivariate spectrophotometric methods were developed and validated for determination of Trandolapril (TR) and Verapamil (VR) combination. The first method for measuring Trandolapril is Constant Multiplication-Spectrum Subtraction (CM-SS), where Trandolapril was measured at 210 nm in its zero-order curve after elimination of Verapamil spectrum. Second and third methods are two Base Points (2BP) and area under the curve (AUC) to measure Trandolapril concentration without depending on the shoulder peak. The fourth method for Trandolapril is Derivative Subtraction (DS) that utilizes the sharp peak appeared in the first order spectrum of Trandolapril. Verapamil was determined by two methods, Constant Multiplication (CM) and Derivative Subtraction-Constant Multiplication (DS-CM). Also, two multivariate methods were developed for measurement of the mixture, Partial Least Squares (PLS) and Principal Component Regression (PCR). All the developed methods were validated as per ICH guidelines and the results proved that the developed methods are accurate and selective. Moreover, a statistical comparison between the developed methods and a reference method was done. Also, One-way ANOVA statistical test was done between all the proposed univariate and multivariate spectrophotometric methods.

Univariate and multivariate spectrophotometric methods for simultaneous determination of avobenzone and octinoxate in pure form and in cosmetic formulations: A comparative study

Simple, economic and precise spectrophotometric and chemometric techniques were used to determine UV filters namely; avobenzone (AV) and octinoxate (OCT) simultaneously in pure form and in cosmetic formulations in concentration range (2–10 μg·mL−1) for both drugs. The spectrophotometric technique includes five different methods; Method (A) is first derivative (D1) spectrophotometry at 380.6 nm for AV and 276.2 nm for OCT, Method (B) is first derivative of ratio spectra (DR1) at 352.8 nm for AV and 312.2 nm for OCT, Method (C) is ratio difference spectrophotometry (RD) at 356 nm and nm 347.2 nm for AV and at 311.6 nm and 281 nm for OCT, Method (D) is mean centering spectrophotometry (MCR) at 356 nm for AV and 301.8 nm for OCT and method (E) is modified Vierordt's method which involves absorbance measurement at 358 nm for AV and 309.2 nm for OCT and determination of the concentration of x and y from the two simultaneous equations. The chemometric technique includes multivariate calibration methods; partial least squares (PLS) and principle component regression (PCR) using the absorption spectra. The proposed methods were applied for determination of (AV) and (OCT) simultaneously in pure form and in cosmetic formulations. These methods were validated according to ICH guidelines.

Stepwise Optimization Strategies Utilizing Recent Univariate and Multivariate Methods for Determination of the Partially Overlapped Mixture Perindopril and Indapamide

Recently, different novel univariate methods were presented for determination of mixtures of drugs having partially overlapped UV spectra. These methods are used when one component is more extended than the other. In this study, these methods were tested for determination of Perindopril and Indapamide. The main problem with Perindopril is the absence of a sharp peak in the zero-order spectrum. The main concern was to test the applicability of the already developed methods for the determination of this type of analytes when present in mixture form. The utilized univariate methods for the determination of Perindopril were; ratio subtraction (RS), ratio subtraction-two base points (RS-2BP), ratio subtraction-area under the curve (RS-AUC), derivative subtraction (DS), derivative subtraction-two bas points (DS-2BP), and derivative subtraction-area under the curve (DS-AUC). While Indapamide was determined by ratio subtraction-constant multiplication (RS-CM), and derivative subtraction-spectrum subtraction (DS-SS) methods. Also, two multivariate spectrophotometric methods were developed and validated, Principal Component Regression (PCR) and Partial Least Squares (PLSs). Validation of the developed methods was done as per ICH guidelines. Also, a statistical comparison with the reported methods was done showing no significant difference.

Determination of Flucloxacillin-sodium in Binary Mixture with Ampicillin-trihydrate Using Univariate and Multivariate Spectrophotometric Methods: A Comparative Study

Objectives: The aim of this study was to develop four simple and accurate spectrophotometric methods for determination of flucloxacillin-sodium in binary mixture with ampicillin-trihydrate without separation. Methods: One of them was a univariate constant center method and the other three methods were multivariate chemometric methods named; Savitsky-Golay filters, continuous wavelet transform of ratio spectra and wavelet transform of first derivative of the ratio spectra. Results: The proposed methods adopted for selective determination of flucloxacillin-sodium and obey Beer’s law in the range (2-20 µg mL-1). Conclusion: The proposed methods were simple, rapid, economic, accurate and precise; they were successfully applied for the determination of flucloxacillin-sodium in pure form and in pharmaceutical preparations.

Validated Univariateand Multivariate Spectrophotometric Methods for Determination of Paracetamol, Ascorbic Acid and Pseudoephedrine Hydrochloride

Simple, precise and economic spectrophotometric and multivariate calibration methods were developed for determination of Paracetamol (PAR), Ascorbic acid (ASC) and Pseudoephedrine hydrochloride (PSH). In method (I) ASC and PSH were determined by applying 1DD spectrophotometric method at 266 and 280 nm for ASC and 218 nm for PSH while PAR was determined by using 1D spectrophotometric method at 257 nm where the linearity ranges are 2-16, 3-40 and 2-28 μg/mL for ASC, PSH and PAR, respectively. While in the developed MCR method the absorption spectra of PAR, ASC and PSH were recorded over 200-400 nm and divided by the spectrum of suitable divisor of PAR, ASC and PSH then the obtained ratio spectra were mean centered. The amplitudes at 287, 286 and 290 nm for PAR, ASC and PSH, respectively were determined where the linearity ranges are 4-20, 3-40 and 2-28 μg/mL for ASC, PSH and PAR, respectively. In method (III) the developed PCR and PLS models were built using a calibration set consisting of seventeen mixtures while the validation set consisted of different eight mixtures in the range of 206-290 nm. The accuracy and precision of the developed methods were proved while their selectivity has been tested by their application for determination of the studied components in different synthetic mixtures. Statistical comparison of the suggested methods with the reported HPLC one using F-and student’s t-tests showed no significant difference.

Bivariate and Multivariate Spectrophotometric Methods for Determination of Ezetimibe with Kinetic Study of Its Alkaline Degradation

The first study concerned with the determination of ezetimibe EZE in presence of its alkaline degradation product were developed and validated using different chemometric techniques [bivariate, classical least square (CLS), and principle component regression (PCR), partial least square (PLS)], with kinetic study and calculation of half-life time and activation energy which essential for quality control of its product. Application of the suggested techniques were successfully applied in synthetic mixture and in pharmaceutical preparations, the results obtained by the proposed techniques were statistically comparable with those obtained by the reported method. All the proposed techniques were validated according to international conference on harmonization (ICH) guidelines.

Spectrophotometric Multicomponent Analysis of Irbesartan, Hydrochlorothiazide and Ramipril in Pharmaceutical Formulations by Chemometric Techniques

Multivariate spectrophotometric methods offer an extensive application for quantification of multicomponent mixtures that exhibit severe spectral overlapping. Partial least Squares (PLS) and Principal componenet Regression (PCR) methods were proposed for the spectrophotometric multicomponent analysis of a ternary mixture consisting of Telmisartan(TEL), Hydrochlorothiazide (HCZ) and Ramipril (RAM) without prior separation. In these chemometric techniques, the measurement of the absorbance values were made in the spectral range from 200-350 nm in the intervals of  = 1 nm at 151 wavelengths in the zero order, first and second derivative spectra of the ternary mixtures of these active ingredients in 0.1 M NaOH. The prepared calibrations of both techniques using absorbance data and concentration matrix data sets were used to predict the concentration of the active ingredients in their ternary, binary and single component mixtures. The optimized models were tested on an external validation set containing synthetic mixtures of the mentioned components. The models were finally used to assay the studied drugs in the commercial formulations. The methods are selective for the determination of telmisartan, hydrochlorothiazide and ramipril and overcome the spectral interference. The prediction values for TEL, HCZ and RAM in both models were found satisfactory.

Simultaneous Estimation of Metformin Hydrochloride, Glimepiride and Pioglitazone using First Generation Chemometric Methods

In this study, new feasible UV-Visible spectrophotometric and multivariate spectrophotometric methods were described for the simultaneous determination of Metformin hydrochloride (MET), Glimepiride (GLI) and Pioglitazone (PIO) in combined pharmaceutical tablets. Methanol is used as a solvent for analysis and whole UV region has been scanned from 200-400 nm. The resolution has been obtained by using multivariate methods as Classical least square (CLS), Inverse least squares (ILS), Principal Component Regression (PCR), Partial Least Squares Regression (PLSR) applied to the UV spectra of the mixture. The results obtained from all the methods were found within the limit.

Validated univariate and multivariate spectrophotometric methods for the determination of pharmaceuticals mixture in complex wastewater

Five, accurate, precise, and sensitive univariate and multivariate spectrophotometric methods were developed for the simultaneous determination of a ternary mixture containing Trimethoprim (TMP), Sulphamethoxazole (SMZ) and Oxytetracycline (OTC) in waste water samples collected from different cites either production wastewater or livestock wastewater after their solid phase extraction using OASIS HLB cartridges. In univariate methods OTC was determined at its λmax 355.7nm (0D), while (TMP) and (SMZ) were determined by three different univariate methods. Method (A) is based on successive spectrophotometric resolution technique (SSRT). The technique starts with the ratio subtraction method followed by ratio difference method for determination of TMP and SMZ. Method (B) is successive derivative ratio technique (SDR). Method (C) is mean centering of the ratio spectra (MCR). The developed multivariate methods are principle component regression (PCR) and partial least squares (PLS). The specificity of the developed methods is investigated by analyzing laboratory prepared mixtures containing different ratios of the three drugs. The obtained results are statistically compared with those obtained by the official methods, showing no significant difference with respect to accuracy and precision at p=0.05.

Simultaneous Estimation of Hydrochlorothiazide, Hydralazine Hydrochloride, and Reserpine Using PCA, NAS, and NAS-PCA

In this study, new and feasible UV-visible spectrophotometric and multivariate spectrophotometric methods were described for the simultaneous determination of hydrochlorothiazide (HCTZ), hydralazine hydrochloride (H.HCl), and reserpine (RES) in combined pharmaceutical tablets. Methanol was used as a solvent for analysis and the whole UV region was scanned from 200–400 nm. The resolution was obtained by using multivariate methods such as the net analyte signal method (NAS), principal component analysis (PCA), and net analyte signal-principal component analysis (NAS-PCA) applied to the UV spectra of the mixture. The results obtained from all of the three methods were compared. NAS-PCA showed a lot of resolved data as compared to NAS and PCA. Thus, the NAS-PCA technique is a combination of NAS and PCA methods which is advantageous to obtain the information from overlapping results.

ALTERNATIVE CALIBRATION SYSTEMS FOR THE SIMULTANEOUS SPECTROPHOTOMETRIC DETERMINATION OF COMPOUNDS WITH OVERLAPPING ABSORPTION SPECTRA

Two simple and efficient procedures have been developed for the rapid simultaneous determination of compounds with mutual spectral interference (rifampicin (RIF) and isoniazid (INH)). The first method was based on the UV–Vis spectral signal (190–600 nm) of synthetic RIF and INH aqueous solutions, whereas the second method involved the visible spectral signal registered between 350 and 800 nm after the reaction of INH with a Cu2+/neocuproine complex. Both multivariate spectrophotometric methods show excellent prevision capacity, providing results that are statistically equivalent with those provided by the standard chromatographic procedure. The methods were validated according to criteria established by ANVISA, showing precision, accuracy and robustness compatible with the requirements for new analytical methods, additionally allowing the reduction of waste generation.