Gas-assisted dispersive liquid-phase microextraction (GA-DLPME) has been developed for preconcentration and spectrophotometric determination of copper ion in different water samples. The ionic liquid ...1-hexyl-3-methylimidazolium hexafluorophosphate and argon gas, respectively, were used as the extracting solvent and disperser. The procedure was based on direct reduction of Cu(II) to Cu(I) by hydroxylamine hydrochloride, followed by extracting Cu(I) into ionic liquid phase by using neocuproine as the chelating agent. Several experimental variables that affected the GA-DLPME efficiency were investigated and optimized. Under the optimum experimental conditions (IL volume, 50µL; pH, 6.0; acetate buffer, 1.5molL−1; reducing agent concentration, 0.2molL−1; NC concentration, 120µgmL−1; Ar gas bubbling time, 6min; argon flow rate, 1Lmin−1; NaCl concentration, 6% w/w; and centrifugation time, 3min), the calibration graph was linear over the concentration range of 0.30–2.00µgmL−1 copper ion with a limit of detection of 0.07µgmL−1. Relative standard deviation for five replicate determinations of 1.0µgmL−1 copper ion was found to be 3.9%. The developed method was successfully applied to determination of both Cu(I) and Cu(II) species in water samples.
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•Gas-assisted dispersive liquid-phase microextraction is presented for copper speciation.•Ar gas has been used as disperser to prevent transformation of copper species.•An enrichment factor of 122 has been achieved for determination of copper.•A syringe which usually causes solvent losing in microextraction has been removed.
•A new multi-component photocatalyst with hierarchical nanostructures is developed.•Graphene, TiO2 nanowires and Pd nanoparticles are integrated.•Enhanced light harvesting efficiency in the ...visible-light region was witnessed.•Kinetics of the photocatalytic reduction of 4-nitrophenol were studied.•Photosynergistic roles are identified.
In this work, a new hybrid nanocatalyst, namely titanium dioxide (TiO2) composite nanowires, encapsulated with graphene (G) and palladium nanoparticles (Pd NPs) (designated as G-Pd@TiO2-CNWs), was prepared. In preparing the nanowires, a combination of electrospinning and hydrothermal approaches was employed. The visible-light-driven photocatalytic performance of G-Pd@TiO2-CNWs was investigated using the reduction of 4-nitrophenol (4-NP) as a model reaction. The results showed that G-Pd@TiO2-CNWs converted nearly 100% of 4-NP under visible light irradiation. The reaction kinetics of the photocatalytic reduction of 4-NP was studied by UV–vis spectrophotometry and the apparent rate constant was determined and compared with those for other supported TiO2 catalysts. Furthermore, the spent G-Pd@TiO2-CNWs could be recovered by simple centrifugation and reused. The work is expected to shed new light on the development of G-incorporated hybrid nanostructures for harvesting light energy and on the development of new photocatalysts for the removal of environmental pollutants.
Background: UV-Vis spectrophotometry remains the most accessible spectral method with a high degree of sensitivity and information. The advantage of the method consists in its universality, the ...ability to combine with other methods, the minimum error, as well as its economic efficiency. The objective of this study was the determination of some validation parameters for the spectrophotometric method of dosing piracetam and nicergoline in combined capsules. Material and methods: Agilent 8453 UV-Vis spectrophotometer, reference standards of piracetam and nicergoline, 0.1 M HCl methanolic solution. Validation of the spectrophotometric method according to the requirements of the ICH guide “Q2R1: For analytical procedures and validation”. Results: Linearity was investigated on concentration ranges 5-40 µg / mL. The regression (R2 ) values were 0.9998 for nicergoline and 0.998 for piracetam, respectively. The limit of detection was 1.737 µg / mL for nicergoline and 0.369 µg / mL for piracetam. Quantification limit values were also calculated as 5.265 and 1.118 µg / mL for nicergoline and piracetam, accordingly. The results obtained showed that the developed spectrophotometric method is accurate, precise and robust, because the value of the relative standard deviation was less than 1.0%. Conclusions: The developed spectrophotometric method showed specificity, linearity, accuracy, precision and robustness, and can be applied on the concentration range between 80-120% of the nominal value of the content of nicergoline and piracetam in the preparation.
•In this study, a novel UV–Vis spectrophotometry-colorimetric method was developed and validated.•This method was used to measure the concentration of rivastigmine tartrate (RT) in various biological ...matrices after the application of separable-effervescent microneedles (SEMNs) containing RT.•This method was successfully applied in ex vivo and in vitro permeation, along with in vivo pharmacokinetic studies.
Rivastigmine Tartrate is an acetylcholinesterase inhibitor commonly used in Alzheimer treatment. Due to its hydrophilicity, short plasma elimination half-time, and poor blood-brain barrier penetration, developing a new drug delivery system for RT administration is essential. Accordingly, microneedles offer several advantages and could be a promising drug delivery system for RT administration. One of those types of MNs with numerous advantages is separable-effervescent microneedles. To support the formulation development, an analytical method using UV–Vis spectrophotometry was validated in phosphate buffered saline media and various biological matrices, such as rat skin, brain, and plasma to measure the amount of RT in the SEMNs preparations. The developed analytical method was validated under ICH guidelines. The results showed that the instrument could specifically detect the RT in the preparations without being interfered with by other compounds. The calibration curves in various biological matrices were linear ≥ 0.9985. The LOD and LLOQ values of the PBS media biological matrices were found to be 1.5 and 4.8 µg/mL, 1.2 and 3.7 µg/mL, 0.42 and 1.27 µg/mL, and 0.38 and 1.16 µg/mL, respectively. All the accuracy and precision values of this developed method were within acceptable ranges. Additionally, the extraction recovery was prominent after undergoing the protein precipitation process. As a result, the analytical method was proven to be valid and was successfully applied to quantify the amount of RT in the SEMNs formulation, in vitro and ex vivo permeation, along with in vivo pharmacokinetic studies.
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A sequential method has been used, for the first time, to prepare monodisperse and uniform-size silica nanoparticles using ultrasonication by sol–gel process. The silica particles were obtained by ...hydrolysis of tetraethyl orthosilicate (TEOS) in ethanol medium and a detailed study was carried out on the effect of different reagents on particle sizes. Various-sized particles in the range 20–460 nm were synthesized. The reagents ammonia (2.8–28 mol L
−1), ethanol (1–8 mol L
−1), water (3–14 mol L
−1), and TEOS (0.012–0.12 mol L
−1) were used and particle size was examined under scanning electron microscopy and transmission electron microscopy. In addition to the above observations, the effect of temperature on particle size was studied. The results obtained in the present study are in agreement with the results observed for the electronic absorption behavior of silica particles, which was measured by UV–vis spectrophotometry.
The order of the reaction is the number of concentration factors that affect the speed of a chemical reaction. The reaction order can be used to determine how the adsorption process is in the ...colouring process based on determining the linear regression equation of the R square value. This study aims to compare the gravimetric method with the UV-Vis spectrophotometric method in determining the reaction order in chlorophyll samples of the natural dye papaya leaves. This study used a quantitative method to determine the value of the reaction order of the papaya leaf natural dye, with data analysis techniques including gravimetric method analysis to determine chlorophyll content, UV-Vis spectrophotometry to determine the value of chlorophyll absorbance and linear regression to determine the order of the reaction. The results showed that the two methods followed first order with an R-value of 0.951 for the gravimetric method and 0.994 for the UV-Vis spectrophotometric method. REFERENCES Aisy, G. A. R. (2018). Analysis of the Chlorophyll Content of Papaya Leaf Extract (Upload Papaya L.) Against Extraction Time Variations Using a Hodothermal Extractor. Diponegoro University, (1969), 4–27. Azizah, H. P., & Utami, B. (2016). Utilization of Green Dyes from Papaya Leaves (Carica papaya L.) As a Natural Textile Dyes. UNY National Chemistry Seminar, (October 2016). Fauziah, L., & Wakidah, M. (2019). Extraction of Papaya Leaves (Carica papaya L.) Using Ultrasonic Cleaner. EKSAKTA: Journal of Sciences and Data Analysis, 19(1), 35–45. Khofya, A., & Aji, M. P. (2018). Papaya Leaf Extract (Upload Papaya L.) as a natural dye in batik cloth. Indonesian Journal of Natural Science Education (IJNSE), 1(1), 13–17. Manurung, M. (2012). Mangosteen Peel Application (Garcinia Mangostana L.) As a Natural Dyes on Cotton Fabrics by Pre-Mordanting. Journal of Chemistry, 6(2): 183-190. Matitaputty, J. K., Ufie, A., Ima, W., & Pattipeilohy, P. (2022). Implementation of Education for Sustainable Development (ESD) Through Ecopedagogy in Learning at SMP Negeri 8 Ambon. BUDIMAS Journal, 04(1). http://journal.um-surabaya.ac.id/index.php/JKM/article/view/2203 Namirah, I., Affifah, I., Wijayanti, I. E., & Langitasari, I. (2019). Study of Natural Coloring Plants in the Outer Baduy Community. EduChemia (Journal of Chemistry and Education), 4(2), 204. Pujilestari, T. (2015). Review: Sources and Utilization of Natural Dyes for Industrial Purposes Dynamics of Crafts and Batik, 32(2), 93–106. Retrieved from https://media.neliti.com/media/publications/61575-ID-review-sumber-dan-pemanfaatan-zat-warna.pdf Ribeiro, M. G. T. C., Costa, D. A., & Machado, A. A. S. C. (2010). “Green Star”: A holistic green chemistry metric for evaluation of teaching laboratory experiments. Green Chemistry Letters and Reviews, 3(2), 149–159. Saputra, B. W. (2008). Adsorption System. 6–21. Tugas Akhir Sarjana. Jurusan Teknik Elektro Universitas Indonesia, Jakarta. Sugiyono. (2011). Quantitative Research Methods, Qualitative and R&D. Bandung: Alphabet.
Headspace-Mass Spectrometry (HS-MS), Fourier Transform Mid-Infrared spectroscopy (FT-MIR) and UV-Visible spectrophotometry (UV–vis) instrumental responses have been combined to predict virgin olive ...oil sensory descriptors. 343 olive oil samples analyzed during four consecutive harvests (2010–2014) were used to build multivariate calibration models using partial least squares (PLS) regression. The reference values of the sensory attributes were provided by expert assessors from an official taste panel. The instrumental data were modeled individually and also using data fusion approaches. The use of fused data with both low- and mid-level of abstraction improved PLS predictions for all the olive oil descriptors. The best PLS models were obtained for two positive attributes (fruity and bitter) and two defective descriptors (fusty and musty), all of them using data fusion of MS and MIR spectral fingerprints. Although good predictions were not obtained for some sensory descriptors, the results are encouraging, specially considering that the legal categorization of virgin olive oils only requires the determination of fruity and defective descriptors.
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•Data fusion of three instrumental techniques to predict the intensities of virgin olive oil sensory descriptors.•Objective instrumental analysis to describe sensory properties and distinguish different categories of virgin olive oils.•Optimal PLS models are used to predict the olive oil intensity values.
•The UV–vis spectrum of PEI and complexes with metal ions were investigated.•The UV–vis detection method of Cu2+, Co2+ and Cr3+ with PEI was established.•Stoichiometric ratios of amino groups and ...Cu2+, Co2+, Cr3+ are 4:1, 4:1, and 3:1.•Adsorption process of PEI fitted Freundlich equation better than Langmuir.•Coordination of PEI with metal ions is exothermic, entropy increasing reaction.
Branched Polyethyleneimine (PEI) is biocompatible material and has strong adsorption towards heavy metal ions for abundant amount of primary, secondary and tertiary amine. Spectral response of PEI towards different heavy metal ions was investigated in aqueous solution by UV–vis spectrophotometry. It was found that Cu2+, Co2+ and Cr3+ could be selectively recognized by PEI in terms of blue shift of characteristic absorption peak and changes of absorbance. Static coordination process and coordination dynamics between PEI and Cu2+, Co2+, Cr3+ were systematically investigated. Parameters including stoichiometric ratio, coordination equilibrium constant, isothermal adsorption equation, reaction kinetic equation, activation energy, reaction entropy and reaction enthalpy were calculated and discussed. The maximum adsorption capacity of Cu2+, Co2+ and Cr3+ at room temperature (298K) was 234.25mg/g, 184.98mg/g and 52.08mg/g, respectively, indicating that PEI has strong application in spectrometry recognition and adsorption of Cu2+, Co2+ and Cr3+ heavy metal ions.
Liver is a part of body that is used as a toxin neutralizer as well as a target for increasing free radicals. In counteracting free radicals, body needs antioxidants in one of the plant secondary ...metabolites, namely anthocyanins. Anthocyanins are organic compounds from the water-soluble flavonoid family that give red, blue, and violet colors. Fermentation can increase anthocyanin levels in kidney beans. This study aimed to determine the presence of anthocyanins in kidney bean (Phaseolus vulgaris L.) tempeh which can be used as a hepatoprotective agent and to determine the anthocyanin levels in kidney bean (Phaseolus vulgaris L.) tempeh. Qualitative analysis using HCl and NaOH with positive results showed the color change to solid red then to bluish green and then faded. Determination of total anthocyanin levels was carried out using UV-Vis spectrophotometric method with the pH differential principal in anthocyanin showed in mg/100gram sample at a maximum wavelength of 525.5 nm. The result was that the average anthocyanin content was 40.37mg/100gram with a variant coefficient is 0.325%.
•MO onto Cu@Cu2O nanocomposite follows pseudo-first-order and IPD model.•MO adsorption onto Cu@Cu2O nanocomposite is spontaneous and exothermic process.•Activation energy of 12.4kJ/mol indicates ...physisorption nature of MO adsorption.
In this work, the adsorption behavior of methyl orange onto nanoporous core–shell Cu@Cu2O nanocomposite has been investigated using an UV–vis spectrophotometer, considering the influence of pH value, temperature, additive amount of nanocomposite and initial methyl orange (MO) concentration. The adsorption kinetics of MO on the Cu@Cu2O nanocomposite has been discussed based upon the pseudo-first-order model, intraparticle diffusion model and Langmuir adsorption model. Thermodynamic parameters such as change in Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) have also been evaluated. The negative changes in Gibbs free energy (−18.4 to −15.1kJmol−1) and enthalpy (−51.5kJmol−1) indicate the spontaneous and exothermic nature of the adsorption process of MO. The activation energy (Ea) of 12.4kJmol−1 reveals the physisorption nature of MO adsorption onto the nanoporous Cu@Cu2O nanocomposite.
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