Simultaneous Spectrophotometric Determination Research Articles

Rapid ion pair-based surfactant-assisted liquid-liquid microextraction with solidification of floating organic drop for simultaneous spectrophotometric determination of selected anionic dyes in food samples

Ion pair-based surfactant-assisted liquid-liquid microextraction with solidification of floating organic drops has been developed to extract Allura red (AR), tartrazine (TAR), and fast green (FG) prior to spectrophotometric determination. Cetyltrimethylammonium bromide (CTAB) was employed as ion-pairing agent to enhance the hydrophobic behavior of anionic dyes. 1-undecanol and ethanol were used as the extraction and dispersion solvents, respectively. The dyes were quantitatively extracted in the presence of KCl (0.15 mol L−1) at pH 4.0. The method exhibits wide linearity (15.0–1500.0 μg L−1 for AR, 35.0–2000.0 μg L−1 for TAR, and 3.0–1200.0 μg L−1 for FG) with preconcentration factors of 19.6, 20.1, and 19.9, respectively. The detection limit was 3.7. 9.5, and 0.83 μg L−1 for AR, TAR, and FG, respectively. The relative standard deviation did not exceed 2.1 %. The procedure was applied for the determination of these dyes in food samples.

Simultaneous spectrophotometric and chromatographic determination of Ketorolac and Dexamethasone: Overall assessment regarding environmental Impact, Practicality, and functionality principles

Determination of a drug combination that contains a minor component that is also a poorly UV absorbing analyte represents greet challenges in drug analysis. A fixed-dose ophthalmic combination of ketorolac tromethamine (KET) and dexamethasone sodium phosphate (DEX) (in the ratio of 5:1) is used to relieve post-surgical inflammation and seasonal allergic conjunctivitis due to their analgesic and anti-inflammatory activity. Five spectrophotometric methods and a reversed phase chromatographic separation method were developed and validated for simultaneous determination of both drugs in lab-prepared eye drops. Direct spectrophotometric determination of KET (the major, highly UV absorbing analyte) was achieved from the zero-order UV absorption spectra at 323 nm while DEX (which is the minor, poorly UV absorbing analyte) was quantified after applying several spectrophotometric methods. Either fundamental zero-order spectra or ratio spectra were used, and measurements were done at either single or dual wavelengths. The developed methods were: isosbestic point method, absorption factor method, dual wavelength method, ratio difference UV spectrophotometric method, and simultaneous equation method. The developed spectrophotometric methods determine KET in the linearity range of 2.0–12.0 μg/mL and DEX in the range of 5.0 – 35.0 μg/mL. For accurate spectrophotometric determination of DEX in the ratio of the dosage form, multiple standard addition method was applied. HPLC technique was also applied for separation and quantification of both drugs. Chromatographic separation was attained by using Hypersil ODS-C18 (150 x 4.6 mm, 5 μm) column. The mobile phase was composed of 50 % methanol: 50 % phosphate buffer (pH 2.5). The column compartment was maintained at 25 °C. Flow rate was adjusted at 1.2 mL/min and detection was performed by DAD at 254 nm. The linearity of HPLC method was 5.0–100.0 μg/mL, and 5.0–50.0 μg/mL for KET and DEX, respectively. Simultaneous determination of both drugs was applied to lab-prepared eye drops that contain also benzalkonium chloride as inactive ingredient. The developed methods determined the cited drugs with good and acceptable % recovery. The results of the developed methods and a reported HPLC method were compared using one-way ANOVA test, F-test and student’s t-test at confidence level 95 %, and they show no significant statistical difference. Assessment of greenness of the developed methods in comparison with reported HPLC method was performed using different tools, including analytical eco-scale, GAPI and AGREE. HPLC-EAT was also performed to ensure greenness of developed HPLC method. Moreover, assessment of practicality, applicability, and functionality of developed and reported methods was evaluated by BAGI metric tool and WAC calculator, respectively. The developed methods allow simple, rapid, and accurate analysis of quality control samples that contain KET and DEX.

Machine learning approaches for simultaneous spectrophotometric determination of heavy metal ions in water samples

In this study, the simultaneous determination of Co, Cd, Ni, Cu, and Pb was carried out as a color complex with 4-(2-pyridylazo) resorcinol in an aqueous solution under the assesting of machine learning. A partial least-squares multivariate linear regression and artificial neuron network for the analysis of mixtures of metals were developed. MATLAB is a powerful software machine learning program that was used to support matrix calculations and displays. The benefit of MATLAB in the construction of the machine learning model allows the development of a rapid and highly effective analysis of multiple components in the mixtures without separation and enrichment. For individual determinations, the working ranges were discovered as the important information for choosing the initial concentration of each heavy metal in a mixture, r. The results of analysis of Ni2+, Pb2+, and Cd2+ by two methods Partial Least Squares - PLS and Artificial Neural Networks - ANN are sensitive and accurate for simultaneous determination of the concentration of these ions in the synthesis mixture with a high regression coefficient of 0.993, respectively, 0.997, 0.997 for Ni2+, Pb2+ and Cd2+. As for Cu2+ and Co2+, the accuracy is higher when using the ANN method.

Simultaneous spectrophotometric determination of Co (II) and Co (III) in acidic medium with partial least squares regression and artificial neural networks

This study aims at the application of two chemometric techniques to visible spectra of acetic acid solutions of Co (II) and Co (III) for simultaneous determination thereof. Spectral data of 145 samples in the range of 400–700 nm were used to build the models. Partial least squares regression models were developed for which latent variables were determined using internal cross-validation with a leave-one-out strategy and 3 and 2 latent variables were selected for Co(II) and Co(III) based on root mean square error of cross-validation. For these models, root mean square errors of prediction were 1.16 and 0.536 mM and coefficients of determination were 0.975 and 0.892 for Co (II) and Co (III). As an alternate method, artificial neural networks consisting of three layers, with 10 neurons in hidden layer, were trained to model spectra and concentrations of cobalt species. Levenberg-Marquardt algorithm with feed-forward back-propagation learning resulted root mean square errors of prediction of 0.316 and 0.346 mM for Co (II) and Co (III) respectively and coefficients of determination were 0.996 and 0.988.

Simultaneous Spectrophotometric Determination of Piroxicam, Naproxen, Diclofenac Sodium and Mefenamic Acid in Pharmaceutical Formulations by Partial Least Squares Method

A chemometric method, partial least squares regression (PLS) was applied for the simultaneous determination of piroxicam (PIR), naproxen (NAP), diclofenac sodium (DIC), and mefenamic acid (MEF) in synthetic mixtures and commercial formulations. The proposed method is based on the use of spectrophotometric data coupled with PLS multivariate calibration. The Spectra of drugs were recorded at concentrations in the linear range of 1.0 - 10 μg mL-1 for NAP and from 1.0 - 20 μg mL-1 for PIR, DIC, and MEF. 34 sets of mixtures were used for calibration and 10 sets of mixtures were used for validation in the wavelength range of 200 to 400 nm with the wavelength interval λ = 1 nm in methanol. This method has been used successfully to quantify drugs in pharmaceutical formulations with no interference from excipients. The proposed method is simple, quick, and can be used as an alternative analysis tool in drug and formulation quality control as well as process control.

Absorbance Subtraction Method for the Determination of Losartan Potassium and Hydrochlorothiazide in Bulk and Tablets

A simple, accurate and precise method was proposed for the determination of losartan potassium and hydrochlorothiazide. The overlain spectra of losartan potassium and hydrochlorothiazide were found to have an isoabsorptive point at 266.9nm, while the spectrum of later is extended with an absorption maximum at 325 nm; where the former is not interfering, based on these spectral characteristics, simultaneous spectrophotometric determination of the two analytes in combined dosage was possible using absorbance subtraction method. The method showed good precision in term of repeatability and intermediate precision with relative standard deviations were less than 2% in both cases. The method’s accuracy was confirmed by the close agreement between the theoretical and actual concentrations of the analytes in nine laboratory prepared synthetic mixtures. The proposed method was successfully applied to the analysis of a commercial product, the assay results were 102.60% and 99.88%with %RSD 1.68 and 1.68for LSP and HCT, respectively.

Simultaneous Spectrophotometric Determination of Alogliptin and Pioglitazone Using Partial Least Squares with and without Genetic Algorithm

Simultaneous Spectrophotometric Determination of Alogliptin and Pioglitazone Using Partial Least Squares with and without Genetic Algorithm

Simultaneous spectrophotometric determination of recombined sofosbuvir, ledipasvir and paracetamol together as commonly repurposed drugs for COVID-19 treatment

BackgroundCOVID-19 has emerged as the most serious outbreak in recent years. Certain medications such as sofosbuvir (SOF), ledipasvir (LDV) and paracetamol (PAR) were proposed as a safer and recommended substance to control symptoms of COVID-19.ResultsUsing built-in spectrophotometer software, zero order and derivative spectra of the studied components, two extremely clear, quick, and sensitive spectrophotometric techniques for simultaneous determinations of SOF, LDV, as well as PAR have been developed. LDV was calculated using a zero order absorption spectrum at wavelength maxima of 333 nm. SOF and PAR were evaluated simultaneously using a first derivative spectrophotometer at 247.2 nm and 260.8 nm, respectively. The calibration graphs for SOF, LDV, and PAR are linear over ranges of concentrations of 8–60 µg/mL, 4–22 µg/mL, and 2–14 µg/mL, consequently. The suggested methodologyspecificity was investigated using laboratory manufactured (different ratios) mixtures, which were then effectively used to the analysis of Mpiviropack plus® and Panadol® pills. Valid limitations included accuracy, precision, and specificity. The methodologies were validated in accordance with some ICH standards.ConclusionsThe methods proposed were simple, accurate, precise, and neither require any complex equipment nor specific software.

Comparative study of continuous wavelet transform and multivariate calibration for the simultaneous spectrophotometric determination of tamsulosin and solifenacin in combined dosage form and biological sample.

Spectrophotometry alone is not applicable for the simultaneous determination of drugs in a multi-component pharmaceutical formulation owing to their overlap. In this study, the combination of UV-Vis spectrophotometry and chemometric methods, including continuous wavelet transform (CWT) and partial least squares (PLS) was presented for the simultaneous estimation of tamsulosin (TAM) and solifenacin (SOL) in synthetic mixtures, commercial formulation, and biological sample. The simultaneous spectrophotometric determination of TAM and SOL in binary mixtures, real sample, and biological sample was performed by applying CWT and PLS approaches. In the CWT method, two various wavelet families named Daubechies (db2) at wavelength 223 nm and Biorthogonal (bior1.3) at wavelength 227 nm based on the appropriate zero crossing point were selected for TAM and SOL, respectively. The linear ranges of TAM and SOL were 0.25-4 μg/mL and 10-30 μg/mL, respectively. The limits of detection (LOD) were 0.0459 μg/mL and 0.2085 μg/mL, while the limits of quantitation (LOQ) were 0.3208 μg/mL and 0.6495 μg/mL for TAM and SOL, respectively. The average recovery values of eighteen mixtures were 98.28% and 97.79% for TAM and SOL, respectively. Also, the root mean square error (RMSE) of both components was lower than 2.3. Based on the k-Fold cross-validation in the PLS approach, the optimum number of components related to the TAM and SOL were 9 and 5 with a mean square error prediction (MSEP) of 0.0153 and 0.0370, respectively. The mean recovery values of the test set were found to be 100.09% for TAM and 99.95% for SOL where RMSE values were 0.0064 and 0.0169 for TAM and SOL, respectively. Analysis of variance (ANOVA) was applied to the results of the real sample that there was no significant difference between the proposed methods and the high-performance liquid chromatography (HPLC) as a reference technique. The result obtained revealed that the proposed methods were found to be fast, facile, economical, and precise, which provide a suitable alternative to HPLC technique for the concurrent determination of TAM and SOL in quality control laboratories. UV-Vis spectrophotometry combined with CWT and PLS was developed.Simultaneous analysis of TAM and SOL was performed using the proposed approaches.These methods were implemented on synthetic mixtures, commercial formulation, and biological sample.ANOVA test was used to compare the suggested methods and the HPLC technique.

Simultaneous Quantitative Analysis of Salmeterol and Fluticasone in Inhalation Spray Using HPLC and a Fast Spectrophotometric Technique Combined with a Time Series Neural Network and Multivariate Calibration Methods.

Chromatographic methods have been used for the simultaneous determination of salmeterol (SMT) and fluticasone (FLU). The methods take a lot of analysis time, need sample pre-treatment and large amounts of solvents, and are costly. The aim of this paper was to propose a simple, quick, and low-cost method for the determination of SMT and FLU using a time series neural network and multivariate calibration methods, including partial least-squares (PLS) and principal component regression (PCR). The simultaneous spectrophotometric determination of SMT and FLU in binary mixtures and anti-asthma spray was performed by applying multivariate calibration methods and an intelligent approach. The coefficient of determination (R2) of the time series neural network was obtained: 1 and 0.9997 for SMT and FLU, respectively. The mean recovery of PLS was found to be 99.29% and 99.84% for SMT and FLU, respectively. Also, the mean recovery related to the PCR method was 102.05% and 103.72% for SMT and FLU, respectively. The inhalation spray was assessed using HPLC and the results were compared with chemometrics methods via an analysis of variance (ANOVA) test. Intelligent and multivariate calibration methods were proposed. Simultaneous spectrophotometric determination of salmeterol and fluticasone was studied in an anti-asthma spray. HPLC as a reference method was performed and compared with chemometrics methods. Rapid, simple, low-cost, and accurate are the benefits of the proposed approaches.

Artificial Neural Networks for the Simultaneous Spectrophotometric Determination of Amoxicillin Trihydrate, Metronidazole and Pantoprazole in pharmaceutical Formulations.

Artificial Neural Networks for the Simultaneous Spectrophotometric Determination of Amoxicillin Trihydrate, Metronidazole and Pantoprazole in pharmaceutical Formulations.

A simple and safe approach for simultaneous spectrophotometric determination of nitroglycerin and nitrocellulose in double base solid propellants.

An accurate, simple and safe method was developed for simultaneous determination of nitroglycerine (NG) and nitrocellulose (NC) in double base solid propellants (DB propellants). The proposed method is based on alkaline hydrolysis of NG and NC, and followed by colored reaction of released nitrite ion with p-nitroaniline in the presence of diphenylamine in acidic media and produce azo dye. The absorbance of the azo dye was measured at 534nm. Two sets of reaction conditions were developed. In the first set, at room temperature, only NG was hydrolyzed and calibration curve obtained. In the second set, at 60℃, NG and NC were hydrolyzed simultaneously. Based on obtained amount for the NG at room temperature, and total amount of NG and NC at 60℃, the amount of NC was determined by using stoichiometric equations. The calibration curve was linear over the concentration ranges of 0.2-5.0, 0.5-10μgmL-1 for NG and NC, respectively. The proposed method was successfully applied for the determination of NG and NC in DB propellants with good recoveries ranged from 99 to 101%, and RSD less than 2.0%. The method statistically compared based on t- and F-tests with those obtained in according to military standard method (MIL-STD-286). The results showed that the proposed method offers an accuracy and reliable approach for the determination of these compounds in DB propellants, and can be suggested as a routine method in military quality control laboratories.

Simultaneous spectrophotometric determination of fluphenazine HCl and nortriptyline HCl in presence of their potential impurities perphenazine and dibenzosuberone in bulk and pharmaceutical formulation

Fluphenazine HCl (FLU) is an anxiolytic, while Nortriptyline HCl (NOR) is an anti-depressant. They are co-formulated together to treat depression and schizophrenia. Perphenazine (PER) and dibenzosuberone (DBZ) are the pharmacopeial impurities of FLU and NOR, respectively. Four spectrophotometric and multivariate chemometric methods were developed to determine the two drugs together or in presence of their two impurities in their bulk and pharmaceutical formulation. Method (A) is the triple divisor-ratio derivative (TDR) method, where the zero order spectrum of each component was divided by a mixture of the other 3 components, then the peak amplitudes of the first derivative spectra of FLU, NOR and DBZ were measured at 265, 245.4 and 283.2 nm, respectively. Method (B) is the double divisor-ratio difference-dual wavelength (DD-RD-DW) method, in which each component spectrum mixture was divided by a binary mixture of 2 of the interfering components. In the resulting ratio spectra, the amplitude difference is calculated between 2 wavelengths at which the third interfering component has zero difference. Methods (C and D) are the principle component analysis (PCA) and partial least squares (PLS) models. Methods (A and B) failed to quantify PER (FLU impurity), while (C and D) succeeded to quantify all components. The four methods have been applied for the prediction of the FLU and NOR in their pharmaceutical formulation with good accuracy and precision. The proposed methods have been validated according to the ICH guidelines and the results were within the acceptable limits.

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.

Spectrophotometric simultaneous determination of efonidipine hydrochloride ethanolate and telmisartan in synthetic mixture by first order derivative method

The established method represents the development and validation of a straight forward, precise, accurate, specific and reproducible method for the simultaneous estimation of Efonidipine Hydrochloride Ethanolate and Telmisartan in synthetic mixture. First order derivative of the overlay spectra was used for quantification of both drugs. This method involving the determination of both drugs at their respective zero crossing point working wavelength was observed 231.00 nm (Zero crossing point of Telmisartan) for Efonidipine hydrochloride ethanolate and 238.60 nm (Zero crossing point of Efonidipine Hydrochloride Ethanolate) for Telmisartan using methanol as diluent. International conference on harmonization (ICH) (Q2R1) guideline was used for method validation. The Beer-Lambert’s law obeyed in the concentration range of 2-18 μg/ml and 4-36 μg/ml for Efonidipine Hydrochloride Ethanolate and Telmisartan, respectively. The percentage recovery was found in the range of 98-101 % of Efonidipine Hydrochloride Ethanolate and 98.46-99.77% of Telmisartan. The % relative standard deviation of precision and repeatability study was found beneath 1%. This simple and precise method can be used of both drugs in quality control laboratories. Keywords: Efonidipine Hydrochloride Ethanolate, First order derivative, ICH Q2 (R1), Telmisartan, UV spectroscopy.

Shaker-Assisted Liquid–Liquid Microextraction Followed by Solidification of Floating Organic Droplet and Back-Extraction Procedure besides Partial Least Squares Regression for Simultaneous Spectrophotometric Determination of Benzoic Acid and Sorbic Acid

A shaker-assisted liquid–liquid microextraction followed by solidification of floating organic droplet and the final back-extraction method (SALLME-SFOD-BE) was introduced for the simultaneous quantification of benzoic acid (BA) and sorbic acid (SA) (as the model analytes) in different kinds of food products. The presented method used partial least squares calibration and UV–Vis detection. Then, the organic solvent was solidified and collected from the solution. Finally, the extracted analytes were back-extracted into an alkaline solution and analyzed by UV–Vis. Under the optimized condition, the calibration graph was linear in the range of 1–200 ng mL−1 and 1–250 ng mL−1 (R 2 > 0.995) for BA and SA, respectively. The limits of detection (LODs) of 0.5 ng mL−1 and 0.6 ng mL−1 were determined for BA and SA, respectively. The inter-day relative standard deviations (RSDs) were in the range of 2.9–3.1% and 2.6–2.8% for BA and SA, respectively. The intra-day RSDs were also in the range of 2.6–2.9% and 2.4–2.7%, respectively. The calculated enrichment factor (EF) and percent enrichment recovery (ER%) were within the range of 16.4–16.6 and 98–99 for BA and SA, respectively. The method was used for the determination of selected model analytes in real samples, and satisfactory results were obtained. Since very simple instruments were used, this method is affordable, efficient and convenient for extraction and simultaneous determination of BA and SA in real samples.

Application of PCR and PLS Tools for the Simultaneous Quantification of Praziquantel and Ivermectin Binary Mixtures in Veterinary Tablets

Two chemometric calibration methods, principal component regression (PCR) and partial least squares regression (PLS) were proposed for the simultaneous spectrophotometric determination of praziquantel (PRA) and ivermectin (IVE) in a marketed veterinary formulation without using preliminary separation step. UV spectra of calibration set and samples including PRA and IVE were recorded in the spectral region of 225-315 nm. PCR and PLS algorithms were applied to absorbance data matrix and concentration set including PRA and IVE in the linear concentration range of 20.0-160.0 µg/mL for PRA and 2.0-44.0 µg/mL for IVE. The capability of the PCR and PLS methods were validated by analyzing validation samples. Assay results showed that both PCR and PLS approaches provided an opportunity for quantifying PRA and IVE in veterinary tablet formulation.

An intelligent approach based on hybrid of principal component analysis-fuzzy inference system-adaptive neuro-fuzzy inference system for the simultaneous spectrophotometric determination of sofosbuvir and velpatasvir as antiviral drugs in pharmaceutical formulation and urine sample

In this study, a simple, fast, accurate, and inexpensive chemometrics-assisted spectrophotometric method was developed for the simultaneous determination of sofosbuvir (SOF) and velpatasvir (VEL) as antiviral drugs. Fuzzy inference system (FIS) and adaptive neuro-fuzzy inference system (ANFIS) along with principal component analysis (PCA) were used for the analysis of SOF and VEL in binary mixtures, pharmaceutical formulation, and urine sample. Root mean square error (RMSE) of FIS model was 0.1518 and 0.075 for SOF and VEL, respectively. Also, the average testing error related to the ANFIS method was achieved 2.23 ​× ​10−5 and 5.58 ​× ​10−6 for SOF and VEL, respectively. The range of mean recovery percentage was between 99.76 and 100.41 for both methods. Relative standard deviation (RSD) of the real sample was lower than 0.06% for FIS and ANFIS for both components. Analysis of variance (ANOVA) was applied to the results of the real sample that there was no significant difference between the suggested approaches. PCA-FIS and PCA-ANFIS as efficient and accurate methods can be useful for the simultaneous estimation of binary and ternary mixtures in quality control of pharmaceutical formulations.

Enrichment behavior of electrospun PVDF nanofiber membranes for simultaneous spectrophotometric determination of mixed organic acids in water

Electrospun nanofiber membranes (ENMs) of polyvinylidene fluoride which is known as solid phase extraction materials were fabricated through electrospinning technology. Different electrospinning conditions including polymer content, spinning voltage and flow rate were investigated. The optimal operation conditions for electrospun process were set at 12% of PVDF mass fraction, 12 kV of spinning voltage, 0.5 mL h−1 of flow rate, 15 cm of receiving distance, 22 °C of spinning temperature and 45% of environmental humidity. The self-made ENMs were introduced into a combined method of radial electric focusing solid phase extraction enrichment, ultrasonic elution, UV-Vis detection and PLS calculation for determining benzoic acid, phthalic acid and p-toluene sulfonic acid in aqueous samples simultaneously. The calculation results of unknown sample show that the concentrations of benzoic acid, phthalic acid and p-toluene sulfonic acid were 4.416 mg L−1, 4.976 mg L−1 and 5.27 mg L−1, respectively. The relative standard deviation values of each component are all less than 2% with a relative recovery of 84–119%. The ENMs illustrate their fascinating application prospects in determining trace complex materials in aqueous samples.

H-point Standard Addition Method for the Simultaneous Spectrophotometric Determination of Captopril and Hydrochlorothiazide in Pharmaceutical Formulations

Simultaneous spectrophotometric determination of captopril and hydro-chlorothiazide in pharmaceutical formulations by the H-point standard addition method (HPSAM) is described. Absorbance at 211.5 and 230.3 nm was monitored upon the addition of standard solutions of captopril. The results showed that in prepared mixtures, captopril and hydrochlorothiazide can be determined simultaneously at concentration ratios varying from 1.0:0.8 to 2.5:1.5 μg/mL, respectively. Percentage recovery was found to be 95.33–104.37% for captopril and 96.8–105% for hydrochlorothiazide, with a relative standard deviation (RSD) of 2.46%. The method was successfully used to evaluate the antihypertensive captopril drug in a binary combination of hydrochlorothiazide in real samples with high precision and accuracy within the recovery percentage.