Spectrophotometric Determination Research Articles

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.

Utility of Localized Surface Plasmon Resonance of Gold Nanoparticles for Spectrophotometric Determination of Dobutamine in Pharmaceutical Formulations

Utility of Localized Surface Plasmon Resonance of Gold Nanoparticles for Spectrophotometric Determination of Dobutamine in Pharmaceutical Formulations

Liquid-phase microextraction approach using supramolecular solvent formed in aqueous systems based on di(2-ethylhexyl)phosphoric acid salt: Spectrophotometric determination of antipyrine in saliva

In this study, di(2-ethylhexyl)phosphoric acid salt was investigated as a double-chain anionic surfactant for supramolecular solvent formation in a liquid-phase microextraction procedure for the first time. Inorganic electrolytes (sodium salts) were shown to be coacervation agents, due to their salting-out property in solution of sodium di(2-ethylhexyl)phosphate, obtained by deprotonation of the acid. The physico-chemical properties of the newly synthesised solvents were studied. Sodium carbonate and sodium phosphate were found to be the most suitable coacervation agents, due to their alkaline nature and low viscosity of the supramolecular solvent phases they produce. The extraction ability of the novel solvent was demonstrated in liquid-phase microextraction of a colored derivative of antipyrine from saliva for further spectrophotometric determination. The extraction recovery was found to be 70 %. The proposed green sample preparation technique enabled the exclusion of traditional toxic solvents and reduction of reagent consumption. The satisfactory analytical performance of the procedure was validated with real sample analysis. The calibration graph was linear over the concentration range of 0.03 to 0.5 mmol/L. The limit of detection (3σ) and limit of quantification (10σ), calculated from blank tests, were 0.01 and 0.03 mmol/L, respectively.

Green DES based microextraction method for monitoring brilliant black BN (E151) in diverse food matrices

A green deep eutectic solvent (DES) based microextraction method was established for separation and spectrophotometric determination of E151 in food matrices. DES composed of tetra pentyl ammonium bromide and 1-octanol (1:5) was used. Important analytical microextraction parameters including pH, volume of DES and time of vortex mixing were optimized using Box-Behnken design of Response Surface Methodology. The other variables including composition ratio of DES and sample volume were optimized by one variable at a time optimization process. The method exhibited linear behaviour for E151 having concentration range between 132–12000 µg/L with 30 preconcentration factor. The relative standard deviation, detection limit and quantitation limit were determined to be 5 %, 40 and 132 µg/L, respectively. The scores of analytical greenness and applicability for the method were determined to be 0.69 and 62.5, respectively. pK values of E151 were determined. Extraction mechanisms of E151 were elucidated. The method was applied to foodstuffs and water samples to determine their E151 contents by analyte addition recovery tests with recovery values ranging between 94–103 %.

Interference and Elimination of Fe3+ During Spectrophotometric Testing of Typical Pollutants in Coking Wastewater

As typical pollutants in coking wastewater, pyridine, indole, quinoline, and phenol have the advantages of rapidity and accuracy when determined in aqueous solution using UV spectrophotometry, but the presence of other substances in the water can interfere with the results. In this study, the spectrophotometric detection of pyridine, indole, quinoline, and phenol in coking wastewater was interfered with by Fe3+. To minimize this interference, hydroxylamine hydrochloride (HA) was selected as a masking agent to eliminate the interference of Fe3+ on the detection. The results indicated that spectrophotometric determination was significantly affected by Fe3+, and the level of interference increased with the concentration of Fe3+. HA can effectively reduce the absorbance of Fe3+ in the wavelength range of 250-350 nm. It exhibits a strong masking effect on the determination of Fe3+ in indole and phenol solutions, but it hampers the detection of pyridine and quinoline. HA has a better elimination effect on the interference of different concentrations of Fe3+, which can make the relative error of the determination results of indole and phenol less than 5% and 10%, respectively.

Developing of an eco-friendly liquid-liquid microextraction method by using menthol-based hydrophobic deep eutectic solvent for determination of basic fuchsin dye: assessment of the greenness profile.

Herein, we aimed to develop a new environmentally friendly liquid-liquid microextraction (LLME) method based on hydrophobic deep eutectic solvent (hDES) synthesized using biodegradable dl-menthol and decanoic acid for the spectrophotometric determination of toxic basic fuchsin dye in environmental water samples. The parameters affecting the extraction efficiency such as pH, mole ratio, and volume of hDES (1:2) and type and volume of organic solvent, sample volume, times of vortex, ultrasonic bath and centrifuge, ionic strength, and matrix effect were investigated and optimized. Under optimal conditions, the calibration curve showed linearity in the range of 7.4-167μg L-1 with a coefficient of determination of 0.9994. The limit of detection, intra-day and inter-day precision, and recovery values were 2.25μg L-1, 2.46% and 4.45%, and 105 ± 3%, respectively. The preconcentration and enrichment factors were found to be 30 and 61.5, respectively. The proposed hDES-LLME methodology was successfully applied to the environmental water samples to detect toxic BF dye (95-105%). Finally, the ecological impact of the suggested method was evaluated using the analytical eco-scale (PPS:88), complementary green analytical procedure indexe (ComplexGAPI), and the Analytical GREEnness tool (0.63). The assessment results showed that the presented analytical method can be regarded as a green LLME approach for the determination of the BF in water.

Novel assaying method for the accurate and rapid analysis of antioxidant total capacity based on hexachloroiridate(IV)

We introduce a novel method, namely IrRAC, for assessing total antioxidant capacity utilizing the single electron oxidant hexachloroiridate(IV). This method leverages the 488 nm absorption band of [IrCl6]2− largely reducing interferences from antioxidants and their oxidation products. [IrCl6]2− is stable 6 h in phosphate-buffered saline (PBS) ensuring consistent and reproducible absorbance readings and rendering spectrophotometric determinations under physiological neutrality. Individual assessments of 23 antioxidants reveal a linear correlation between decreasing absorbance and increasing antioxidant concentration. When the IrRAC assay was compared with several established water-based methods, strong correlations were found. Importantly, [IrCl6]2− shows a minimal oxidation of non-antioxidative substances. Moreover, IrRAC performs well with synthetic antioxidant mixtures and real samples, highlighting that the nature of antioxidants dominates the assay without much disturbance. Commercial availability of K2[IrCl6] eliminates the need of pretreatment of the oxidant. Undoubtedly, the new method confers a compelling and cost-effective alternative to the existing electron transfer-based methodologies.

Application of a novel deep eutectic solvent modified carbon nanotube for pipette-tip micro solid phase extraction of 6-mercaptopurine

Background6-mercaptopurine (6-MP) is a chemotherapy drug mainly used to treat leukemia. It is a persistent organic pollutant and can remain in the environment for a long period of time. The presence of 6-MP in the environment poses a number of hazards and needs to be assessed to monitor its potential risk to human health and the environment. However, due to its trace amount in complicated matrices, a clean-up and preconcentration step before its determination is compulsory.ResultsAs a highly efficient adsorbent for the extrication of 6-mercaptopurine (6-MP), a novel carbon nanotube doped with camphor: decanoic acid deep eutectic solvent was synthesized and applied as a packing material for the pipette-tip micro solid phase extraction sorbent of 6-MP from tap, wastewater and seawater samples before its spectrophotometric determination. Characteristics and structure of this adsorbent was fully investigated. Factors affecting extraction, including type and volume of the eluent, ionic strength and pH of the sample solution, amount of adsorbent, and number of extraction and elution cycles were optimized using one-factor-at-a-time and response surface methodologies. The method was found to be linear in the range of 1 to 1000 µg/L with a limit of detection and quantification of 0.2 and 0.7 µg/L, respectively. Reproducibility as relative standard deviation was better than 4.6%.ConclusionApplication of deep eutectic solvent modified carbon nanotube indicated suitable microextraction results and good potential for rapid extraction of trace amounts of 6-MP from different aqueous samples. The amount of sample required for the analysis was less than 10 mL and only 1.5 mg of the adsorbent was used. The total analysis time, including extraction was less than 15 min and the adsorbent could be used for at least 10 times, without significantly losing its adsorption ability. Compared to using unmodified usual carbon nanotubes, deep eutectic solvent doped carbon nanotubes showed 19.8% higher extraction ability.

Spectrophotometric Determination of Some Adrenergic Drugs Using H2O2 and Dichlorophenolindophenol

Spectrophotometric Determination of Some Adrenergic Drugs Using H2O2 and Dichlorophenolindophenol

Spectrophotometric Determination of Selenium in Food Items

Selenium (Se) is an essential element that is obtained from food. To increase the level of selenium in the body, we should consume selenium-rich foods in our diet. The objective of this study was to develop a simple spectrophotometric method for the quantitative analysis of selenium present in food. This study included six food items such as broccoli, cabbage, red cabbage, fenugreek, garlic, and ginger. The new method is based on the yellow colour complex formed by the reaction between 2% potassium iodide and 0.2% pyridine in acidic medium with the selenium. Absorbance was measured at 400 nm against the reagent blank. The results of the above proposed method were compared with the reference method of using potassium iodide and starch as reagents. The selenium content in the examined food samples was determined from the regression equation of the calibration curve y= 0.0799x+0.3477 respectively. All the analyses were performed in triplicate, and the results are expressed as mean ± standard deviation. The highest mean selenium value was obtained in ginger and garlic 18.70 & 18.32 µg/g, respectively among all the studied samples, while the lowest value was in fenugreek seeds 7.38 µg/g. The proposed method is simple, rapid, sensitive, and obeys Beer–Lambert’s law. The proposed method was successfully applied to determine food items. Selenium has been quantitatively analysed for its potential to protect the body from many degenerative diseases. Selenium-rich food, as studied here, should be used as a supplement in the human diet.

Green chemometric-assisted UV-spectrophotometric methods for the determination of favipiravir, cefixime and moxifloxacin hydrochloride as an effective therapeutic combination for COVID-19; application in pharmaceutical form and spiked human plasma

As pharmaceutical analysis progresses towards environmental sustainability, there is a growing need to enhance the safety and health conditions for analysts. Consequently, the incorporation of chemometrics into environmentally friendly analytical methods represents a promising approach. Favipiravir, cefixime, and moxifloxacin hydrochloride have been currently used in COVID-19 treatment. In this study, we develop spectrophotometric methods depending on chemometric based models to measure the levels of favipiravir, cefixime, and moxifloxacin hydrochloride in pharmaceutical preparations and spiked human plasma. It is challenging to determine favipiravir, cefixime, and moxifloxacin simultaneously because of overlap in their UV absorption spectra. Two advanced chemometric models, partial least square (PLS) and genetic algorithm (GA), have been developed to provide better predictive abilities in spectrophotometric determination of the drugs under study. The described models were created using a five-level, three-factor experimental design. The outcomes of the models have been thoroughly assessed and interpreted, and a statistical comparison with recognized values has been taken into consideration. The analytical eco-scale and the green analytical procedure index (GAPI) evaluation methods were also utilized to determine how environmentally friendly the mentioned models were. The outcomes demonstrated how well the models described complied with the environmental requirements.

Spectrophotometric Determination of Hydroxycinnamic Acids in Herbal Drugs. Part 2. Determination of Hydroxycinnamic Acids in the Presence of Polyphenolic Compounds (Review)

INTRODUCTION. Polyphenolic compounds of various classes have pronounced absorption bands overlapping in almost the same ultraviolet region. This superposition of bands complicates the quantification of total hydroxycinnamic acids in herbal drugs by direct spectrophotometry without additional sample preparation.AIM. This study aimed to establish the possibility of quantifying hydroxycinnamic acids in herbal drugs by spectrophotometry in the presence of other polyphenolic compounds.DISCUSSION. This review analyses publications on analytical procedures for the spectrophotometric quantification of hydroxycinnamic acids that are based on the preliminary separation or chemical modification of polyphenolic compounds (combining the use of spectrophotometry, chromatography, extraction, Arnow’s reagent, etc.). The described sample preparation can help to resolve absorption bands in the spectra of polyphenolic compounds. The results of assessing the characteristic parameters of these analytical procedures (selectivity, sensitivity, labour intensity, etc.) can serve as a basis for searching novel approaches to the quantitative determination of hydroxycinnamic acids in plants.CONCLUSIONS. To determine the content of hydroxycinnamic acids in mixtures of polyphenolic compounds, analysts may use special sample preparation (combining spectrophotometry with chromatography and extraction) or chemical modification of the initial compounds. The acquired spectra could benefit from specific mathematical processing (derivative photometry and Vierordt’s method). However, even with the abovementioned approaches, it may not always be possible to increase the selectivity of an analytical procedure. Therefore, there is a need to further improve existing analytical procedures for the quantification of hydroxycinnamic acids and develop new ones.

Spectrophotometric Determination of Hydroxycinnamic Acids in Herbal Drugs. Part 1. Direct Spectrophotometry (Review)

INTRODUCTION. Current scientific research aims to discover new plant sources of hydroxycinnamic acids for the development of novel medicinal products. Most commonly, the quantitative determination of hydroxycinnamic acids in herbal drugs involves testing procedures based on spectrophotometry and its modifications.AIM. This study aimed to establish the possibility of the quantification of hydroxycinnamic acids in herbal drugs by direct spectrophotometry.DISCUSSION. This review presents organised information on the use of direct spectrophotometry to quantify hydroxycinnamic acids in 70 plant species growing or cultivated in the Russian Federation. The review covers publications in Russian for the period from 2007 to 2023. According to the reviewed publications, direct spectrophotometry is an easy-to-use and highly reproducible method that does not require additional reagents or labour-intensive steps. Direct spectrophotometry may result in an overestimation of the hydroxycinnamic acid content due to overlapping absorption bands of polyphenolic compounds with different structures.CONCLUSIONS. Direct spectrophotometry can be considered as a method for measuring the total content of phenolic compounds (as well as hydroxycinnamic acids) in herbal drugs. Different approaches to direct spectrophotometric quantification of hydroxycinnamic acids in herbal drugs by can serve as a methodological basis for developing analytical procedures specific to the chemical compositions of biologically active compounds in herbal drugs and their extracts.

Simultaneous UV-Visible Spectrophotometric Determination of Nelfinavir and Quercetin in Patented Pharmaceutical Formulation and Bulk by First-Order Derivative Spectroscopic Method

Simultaneous UV-Visible Spectrophotometric Determination of Nelfinavir and Quercetin in Patented Pharmaceutical Formulation and Bulk by First-Order Derivative Spectroscopic Method

Micellar Matrices for Spectrophotometric Determination of 5-Aminosalicylic Acid in Medicinal Preparations Using Response Surface Methodology and Box-Benken Plans

Determination of the content of insoluble pharmaceutical substances in dosage forms is an urgent task, since their dosage is very important for the optimal ratio between the therapeutic effect and ensuring the necessary bioavailability. The use of micellar media as a matrix allows increasing solubility. This report presents the results of the influence of the micellar system consist from cetyltrimethylammonium bromide, CTAB, dimethyl sulfoxide, DMSO and water on the determination of the content of 5-aminosalicylic acid (5-ASA) in pharmaceutical substances and in dosage forms. 5-ASA is widely used for the treatment of inflammatory bowel diseases, ulcerative colitis and Crohn's disease. To obtain the optimal matrix, the methodology of the response surface (MRS) and three-level Box-Benken plans (BBP) were used. The intensity of the absorption band of 5-ASA (A330), which reflects the acid content, was used as the target function. The independent factors were: the concentration of CTAB (pC(CTAB), mol/l); the acidity of medium (pH); the proportion of DMSO in the binary solvent (αDMSO). The BBP consisting of fifteen compositions were compiled and response surfaces constructed. Optimal conditions for the determination of 5-ASA by the absorption band A330 are: pC(CTAB) = 1.1, pH = 7.6, α(DMSO) = 0.3. In this matrix, the content of 5-ASA in the pharmaceutical substance was established and good metrological performance was achieved. The use of MRS and BBP contributes to the development of effective methods for quality control of 5-ASA dosage forms from different manufacturers.

A spectrophotometric determination and the quantum chemical investigation of Pd(II)-3-hydroxy-2-(4-methoxyphenyl)-4-oxo-4H-1-benzopyran complex

An analytical approach has been instigated for spectrophotometric inquisition of trace amounts of palladium in its bivalent oxidation state employing a novel 1-benzopyran derivative viz. A 1:2 [Pd(II):HMPB] light yellow complex is formed by a spontaneous interaction between Pd(II) and HMPB. The complex is quantitatively extracted from a weakly basic medium into dichloromethane absorbing prevalently and consistently at 405-425 nm. The method coheres to linearity up to 1.5 µg mL-1 of palladium(II). Analytical parameters such as the molar absorption coefficient (ε=3.011 × 104 L mol-1 cm-1), Sandell's sensitivity [0.0035 µg Pd(II) cm-2], % RSD (0.62%) and the limit of detection [0.0147 µg Pd(II) mL-1] indicate that the study satisfies all the criteria for good sensitivity, precision and accuracy. In addition, intervention with regard to numerous anions/complexing agents and cations of primary analytical importance has been performed to assess the method's flexibility and usefulness. The results show that the majority of them do not cause any interference during determination. To better understand chemistry of the prepared complex, spectroscopic quantum chemical studies including DFT and MEP mapping based on examination of the electronic characteristics of the complex in its most stable least energy conformation are used.
 KEY WORDS: Palladium, 3-Hydroxy-2-(4-methoxyphenyl)-4-oxo-4H-1-benzopyran, Extractive spectrophotometric determination, DFT, MEP, Docking
 Bull. Chem. Soc. Ethiop. 2024, 38(3), 591-603. 
 DOI: https://dx.doi.org/10.4314/bcse.v38i3.4

Spectrophotometric determination of amoxicillin in pharmaceutical formulations using normal and reverse flow injection analysis systems: A comparison study

The combination of flow injection technique and spectrophotometric detection can be employed for the rapid and low-cost methods for antibiotic assay. In this work, two flow injection analysis (FIA) systems, normal and reverse (nFIA and rFIA), combined with UV-Vis spectrophotometric technique were used for amoxicillin determination in its pure and pharmaceutical preparations. A colorimetric coupling reaction between amoxicillin and diazotized p-toluidine produced a bright yellow azo dye and quantified at a maximum wavelength of 426 nm. For nFIA and rFIA procedures, the amoxicillin calibration graphs had an RSD of less than 2% and were linear in the ranges of 5-200 and 1-140 µg/mL, respectively. The limits of detection and quantification were 1.41 and 4.71 µg/mL of amoxicillin for nFIA and 0.39 and 1.31 µg/mL for rFIA, respectively. The physical and chemical factors that could influence color sensitivity were investigated. Various commercial formulations containing different amounts of amoxicillin were successfully tested using the developed approaches, which demonstrated to be easy, rapid, reproducible, and interference-free.
 KEY WORDS: Amoxicillin, Normal FIA, Reverse FIA, p-Toluidine, Diazotization reaction
 Bull. Chem. Soc. Ethiop. 2024, 38(3), 577-590. 
 DOI: https://dx.doi.org/10.4314/bcse.v38i3.3

Spectrophotometric Determination of Remdesivir Using the Ion Pair Complex Method Using through Alizarin Red S Dye

The research included the development of a simple and practical spectroscopic method for the estimation of remdesivir (RDV) by the ion-pair method, which is based on the interaction of RDV with Alizarin Red S (ARS) at laboratory temperature. Using water as a medium for the reaction, a product Red in color was formed, with a linear relation ranging from 1 to 25 ?g/ml. It gave the highest absorption at wavelength 524 nm, and the complex completed its reaction after an hour, as the value of the sample was a relative standard deviation of no more than 1%, the recovery rate is 100.2429%, and high sensitivity to low concentrations, where she was the values of limit of detection, limit of quantitation were 0.0198, 0.0602 ?g/ml, respectively, detection limit of 0.0139 ?g/mL, and a quantitation limit of 0.0422 ?g/mL. The molar absorptivity is 51340.668 L/mol/cm, and Sandell?s sensitivity value is 0.0117 ?g.cm-2. The recovery values ranged from 99.3088% to 100.5184%, with a relative standard deviation not exceeding 0.7886% for RDV. The method was successfully applied for the estimation of pharmaceutical preparations using both direct and standard addition methods.. KEYWORDS :Alizarin red S, Ion pair, Remdesivir, Spectrophotometric estimation.

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

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

Spectrophotometric determination of phenol impurity in phenoxyethanol and phenol index of drinking water and municipal wastewater effluent after salting-out assisted liquid phase microextraction (SA-LPME)

In this study, a novel and convenient analytical method based on salting-out-assisted liquid phase microextraction (SA-LPME) has been developed. A spectrophotometric technique was employed to quantify the concentration of phenol in drinking water and treated wastewater, as well as the phenol impurity in 2-phenoxyethanol (PE). To accomplish this, a solution containing dissolved PE was supplemented with 4-aminoantipyrine (4-AAP) and hexacyanoferrate. Subsequently, NaCl was added to induce the formation of a two-phase system, consisting of fine droplets of PE as an extractant phase in the aqueous phase. The resulting red derivative was then extracted into the extractant phase and separated through centrifugation. Finally, the absorbance of the extracted derivative was measured at 520 nm. The Response Surface Methodology (RSM) based on the Box-Behnken Design (BBD) was employed to optimize the influential factors, namely 4-Aminoantipyrine (4-AAP), buffer (pH = 10), hexacyanoferrate, and NaCl. By utilizing the optimal conditions (buffer: 50 μL, 4-AAP (1% w/v): 80 μL, hexacyanoferrate (10% w/v): 65 μL, and NaCl: 0.7 g per 10 mL of the sample), the limit of detection was determined to be 0.7 ng mL−1 and 0.22 μg g−1 for water and PE samples, respectively. The relative standard deviation (RSD) and correlation of determination (r2) obtained fell within the range of 2.4–6.8% and 0.9983–0.9994, respectively. Moreover, an enrichment factor of 65 was achieved for a sample volume of 10 mL. The phenol concentration in two PE samples (PE-1, PE-2), provided by a pharmaceutical company (Pars Sadra Fanavar, Iran), were determined to be 0.83 ± 0.05 μg g−1 and 2.70 ± 0.14 μg g−1, respectively. Additionally, the phenol index in drinking water and treated municipal wastewater was found to be 3.60 ± 1.06 ng mL−1 and 4.60 ± 1.17 ng mL−1, respectively. These mentioned samples were spiked in order to evaluate the potential influence of the matrix. The relative recoveries from PE-1, PE-2 samples, drinking water, and treated municipal wastewater samples were measured as 104.5%, 97.5%, 101.6%, and 107.8%, respectively, indicating no matrix effect.