There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Statistics for analytical chemistry

In situ chemical oxidation of a carbamazepine solution was performed using persulfate anions simultaneously activated by heat energy (thermal, ultrasound), UV-C light, Fe2+ ions, and hydrogen peroxide. The main objective of this study was to analyze the mineralization reactions that occurred during the studied operating conditions. Solution TOC removal was nearly complete (99%) within 90 min, which prevented the accumulation of toxic intermediates. The mineralization process of carbamazepine solutions can be described using pseudo-second-order kinetics. Under acidic conditions, Fe2+ can exhibit catalytic effects on H2O2 decomposition and persulfate activation. With excess persulfate, an unproductive S2O82− decomposition reaction (with no generation of SO4 −) or a rapid reaction between excess sulfate radicals to produce sulfate anions could occur. Sulfate and hydroxyl radicals were involved in the main mineralization pathway. The influences of chloride ions on mineralization were also evaluated. The results demonstrated that this activated persulfate-based oxidation system could be used to control water pollution by emerging contaminants, such as carbamazepine.

In situ chemical oxidation of carbamazepine solutions using persulfate simultaneously activated by heat energy, UV light, Fe2+ ions, and H2O2

Chemometrics: A Textbook

Occurrence, interactive effects and ecological risk of diclofenac in environmental compartments and biota - a review

The molecular structure of alkali metal rosmarinates was studied in comparison to rosmarinic acid using FT-IR, FT-Raman, 1H and 13C NMR spectroscopy, as well as density functional theory (DFT) calculations. The B3LYP/6-311+G(d,p) method was used to calculate optimized geometrical structures of studied compounds, atomic charges, dipole moments, energies, as well as the wavenumbers and intensities of the bands in vibrational and NMR spectra. Theoretical parameters were compared to experimental data. Antioxidant activity was determined using two spectrophotometric methods: (i) Assessing the ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) stable radical and (ii) assay of antioxidant power of ferric ions reducing (FRAP). The linear correlations were found between HOMO–LUMO (highest occupied molecular orbital–lowest unoccupied molecular orbital) energy gap and the reducing power expressed as FRAP (R = 0.77) as well as between IC50 values (the ability of quenching DPPH radicals) and Δνas-s(COO) in IR spectra (differences between asymmetric and symmetric stretching vibrations bands) (R = 0.99). Photochemical properties of studied compounds were also evaluated. The influence of alkali metal on the electronic system of the rosmarinic acid molecule was discussed.

https://www.mdpi.com/1420-3049/24/14/2645/pdf

Molecular Structure and Antioxidant Properties of Alkali Metal Salts of Rosmarinic Acid. Experimental and DFT Studies.

Application of derivative spectrophotometry for determination of coenzyme Q10 in pharmaceuticals and plasma

Analytical methods based on measurements of UV or visible light absorption belong to the most popular and most often used in laboratory practice. Commercially available apparatuses are cheap and easy for operation. Spectrophotometric procedures usually are not timeand labour-consuming. The economical aspects of UV-Vis techniques is worth of emphasize too. It is one of the cheapest technique, so spectrophotometers are basic equipment of every laboratory. The main disadvantage and limitation of the spectrophotometry is its low selectivity. The measurement of absorbance is burden by interferences derived from others components of sample. A recorded UV-Vis spectrum is the sum of absorbances of analyte and matrix. Usually, recorded bands are well-defined but more or less distorted by a background. As the background is called absorbance exhibited by matrix (reagents or accompanied compounds). The problem with specific or nonspecific background can be omitted by measurements versus blank. Such procedure can be successfully applied only in the case of simple samples, which composition is stable and well known or when highly selective reagents are used. An isolation of an analyte from matrix is another solution for increasing the selectivity of assay. But every additional operation introduced into sample preparation procedure extents time and costs of single analysis and increases risk of loss or contamination of the analyte.

/pdf/basic-principles-and-analytical-application-of-derivative-5atrlrdwf6.pdf

Basic Principles and Analytical Application of Derivative Spectrophotometry

The emission of platinum group metals from different sources has caused elevated concentrations of platinum and palladium in samples of airborne particulate matter, soil, surface waters and sewage sludge. The ability of biomass of Aspergillus sp. and yeast Saccharomyces sp. for removal of Pt(IV) and Pd(II) from environmental samples was studied in this work. The pH of the solution, the mass of biosorbent, and contact time were optimized. The Langmuir and Freundlich adsorption isotherms and kinetic results were used for interpretation of the process equilibrium of Pt(IV) and Pd(II) on both microorganisms. The maximal efficiency of retention of Pt(IV) on yeast and fungi was obtained at acidic solutions (pH 2.0 for Pt(IV) and pH 2.5–3.5 for Pd(II)). The equilibrium of the biosorption process was attained within 45 min. The best interpretation for the experimental data was given by the Langmuir isotherm. Kinetics of the Pt and Pd adsorption process suit well the pseudo-second-order kinetics model. Fungi Aspergillus sp. shows higher adsorption capacity for both metals than yeast Saccharomyces sp. The maximum adsorption capacity of fungi was 5.49 mg g−1 for Pt(IV) and 4.28 mg g−1 for Pd(II). The fungi possess the ability for efficient removal of studied ions from different wastewater samples (sewage and road run-off water). It was also demonstrated, that quantitative recovery of Pd from industrial wastes could be obtained by biosorption using Aspergillus sp.

https://www.mdpi.com/2073-4441/11/7/1522/pdf

Joanna Karpińska

Papers

Molecular Structure and Antioxidant Properties of Alkali Metal Salts of Rosmarinic Acid. Experimental and DFT Studies.

Application of derivative spectrophotometry for determination of coenzyme Q10 in pharmaceuticals and plasma

Basic Principles and Analytical Application of Derivative Spectrophotometry

Removal of Platinum and Palladium from Wastewater by Means of Biosorption on Fungi Aspergillus sp. and Yeast Saccharomyces sp.

Simultaneous LC determination of some antidepressants combined with neuroleptics.