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This paper discusses approaches for verification of methods of measurements of chemical and physical characteristics of specific samples. The limitations of well-known approaches are discussed. Some examples of alternatives are given to demonstrate specific issues encountered in the research laboratory analyzing new materials or characterizing new properties of materials. Application of sequential procedure using lower quantities of samples and reagents is presented. A standard addition to solid samples is discussed. The approach of control charts for estimation of method uncertainty for determination of plant available phosphorus is presented. The method comparison is applied as an approach to verification of alkaline reactivity by inductively coupled plasma–optical emission spectroscopy (ICP-OES) measurement, as well as density of newly synthesized chalcogenide glass materials. The presented examples demonstrated that alternative approaches are needed in order to verify the methods applied due to the great variety of activities and corresponding tasks in a research laboratory.

Gunshot residue (GSR) is a material formed during firearm discharge with a specific spheroidal/noncrystalline morphology and chemical composition. The examination of gunshot residue by SEM/EDS is an important tool in forensic studies and presents supporting evidence in criminal investigations. This study is aimed at exploring the number of particles characteristic of GSR identified by SEM/EDS as a function of time, gun caliber, the number of shots, and weather conditions. Firearms typically used in criminal cases in Kosovo were studied, and the experiments were conducted outdoors in the summer and winter seasons. Nine people made different numbers of shots from one to nine and followed a common office routine. An optimized and validated SEM/EDS protocol was applied with a sensitivity of 95%, a bias of −5%, a repeatability of 2% (RSD), a within-lab reproducibility of 2% (RSD), and an expanded uncertainty of the number of GSR particles of 6% at coverage factor k = 2. The results showed that GSR particles could be identified by SEM/EDS five to seven hours after shooting, depending on the weapon used and number of produced shots. The results will benefit forensic scientists by providing a supportive tool for hypothesizing the time interval between firearm discharge and GSR sampling.

The influence of three varieties of surfactants on intermolecular interactions in the bulk phase of a film-forming polyphenylsiloxane was studied by viscosimetric and dielectrometric methods. A linear increase of specific viscosity with increase of polyphenylsiloxane concentration at constant temperature was observed. In solutions of all studied amine derivatives at concentrations above 0.5 g/dm3 , a significant deviation from the linear dependence of the specific viscosity with surfactant concentration was found. The results indicated the formation of associated structures. The viscosity incremental growth in the concentration range of 0.5-2 g/dm3 corresponded to the molecule-weight ratio of amino derivatives. Rheological properties of solutions of the studied amino derivatives was slightly effected by the temperature. The specific viscosity of solutions of low molecular weight amines increased at higher temperatures. The most pronounced change was noticed at concentration of surfactant of 0.5 g/dm3 . The effect was supposed to be due to solvation processes. In contrast, the specific viscosity of the solutions of high molecular weight amine derivatives decreased with increase of temperature up to T = 313 K. It was supposed that the temperature increase caused an increase in intermolecular interactions within the associates, which was accompanied by a decrease of their dimensions. The formed intermolecular structures folded into a tight ball creating less resistance for a flow and as a result the specific viscosity decreased. At increased surfactant concentrations (CSURF> 0.25 g/dm3 ), two types of association processes (mono and hetero-) were established depending on the individual characteristics of the organic amino derivatives (composition, structure, shape and hydrocarbon radical length). It has been proved that, the interaction between each other (monoassociation) was energetically more favorable for high-molecular amines with the simultaneous introduction of polyphenylsiloxane solutions macromolecules (mixed miccels) into their composition. In the solutions containing low-molecular amines, monoassociation processes were proved

Modern varieties of agricultural plants have reached the limits of natural genetic variability in a few key parameters, and a further significant increase in their productivity and stress resistance using traditional approaches is extremely difficult. The use of biostimulants of various nature is considered as a promising way of sustainable development, allowing to increase yields without harmful effects on the environment. Plants are a source of a wide variety of biologically active substances (BAS), such as vitamins, alkaloids, glycosides, saponins, tannins, polysaccharides (gums, mucus, pectins, inulin, fibre, starch), flavonoids, resins, essential and fatty oils, organic acids, phytoncides, pigments and others. An important argument in favour of obtaining biologically active substances from poplar is the environmental friendliness of such a solution, since a lot of unused waste (bark, branches, wood) is generated during the logging process. The purpose of this study is to find the optimal extraction conditions and to investigate the influence of balsamic poplar extract on the change in physiological and biological parameters, as well as the productivity of soybean, cucumber, and sugar beet seeds. The qualitative composition of extracts from buds, twigs, catkins, and poplar wood processing waste has been determined. Among these extracts, the one from poplar wood processing waste is the most promising for further study due to its high content of flavonoids, tannins, saponins, amino acids, and polysaccharides. The optimal technological parameters for extracting these compounds have been identified, including the degree of grinding of the raw materials, the ratio of raw materials to extractant, the duration of extraction, and the concentration of the extractant. It has been found that the best extraction of flavonoids occurs when the raw materials are ground to a size of up to 15 mm and mixed with a ratio of 1:15 of raw materials to extractant for 36 hours using 96 % ethanol. The aftereffect of the application of the extract was traced in the ontogenesis of plants on the change in important physiological processes that influenced the productivity of products and their quality. [ABSTRACT FROM AUTHOR]

A protocol for determination of the content of dye in а mixture for orange smoke grenades was proposed. The protocol was based on spectrophotometric determination of the dye 1.4- dihydroxyanthraquinone in DMSO solutions. The Beer’s law is obeyed in the concentration range of (0.5 -1.2) x10-5 mol/l dye with molar absorptivity 7.3x103 L/mol.cm. The protocol is very fast and show good accuracy (recovery 98.6 - 103.6 %) and precision (RSD 3.8%). Theprotocol was applied in model and real samples.

Sol-gel method opens new possibilities for synthesis of anomaterials with application in biotechnology and medicine as matrices for immobilization of cells, enzymes and other biomolecules. The main purpose of the present work is to study of the sol-gel synthesis and the structure of silica hybrid nanomaterials containing different quantities of organic component. FT-IR spectra show that in hybrids synthesized by ETMS or MTES strong chemical bonds are observed. The average size of nanoparticles on the sample surface is about 20 - 50 nm and formation of self-organized structures is observed.

Technological control of nitration of organic compounds needs data about a composition of acid nitrating mixture before and after nitration. Content of water is a crucial factor for efficiency and safety of the nitration process. The industrial laboratories demands for fast, accurate, precise, low cost and easy to maintain analytical methods. This paper presents the development of a protocol for determination of composition of acid nitrating mixture. The determination of nitric acid is based on redox back titration. Determination of sulfuric acid is based on direct precipitation titration. Water content is determined by calculation. The proposed method showed good accuracy, precision and selectivity, with recoveries (99.80±0.06)% H2SO4 and (98.91±0,80)% HNO3,and total analysis time 20 min..

This study identifies a source of heavy metal pollution in the Tarnița-Ostra area, Suceava County, Romania, using both chemical and biological techniques. Samples collected from the sterile dumps and the surrounding soil were digested and analyzed for total metals and arsenic by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and atomic absorption spectrometry (AAS). High concentrations of heavy metals, such as copper (3.12 g/kg), arsenic (0.68 g/kg), lead (2.67 g/kg), zinc (0.43 g/kg) and barium (0.54 g/kg), found in that region, may pose a high risk to the environment and public health through the food chain. The large amounts of Cu, Fe, Pb, Zn and As of the collected samples diminished much the germination of wheat (Triticum aestivum L.), used in this study as a marker of toxicity. However, after the removal of the heavy metals by treating the aqueous extracts with sodium hydroxide solutions, the germination parameters returned to normal. The quantification of heavy metal levels by ICP-OES provides a better understanding of the potential ecological risks and contamination status of the tailings dumps. Instead, wheat germination tests can be reliable and inexpensive biological methods to prove the harmful effect of heavy metals and arsenic on plants. [ABSTRACT FROM AUTHOR]

The present work aims to study the quality of wort produced using fluoride containing mineral water. The results show that the mineral water has a negative impact on the enzymatic destruction of starch, proteins, color intensity and pH of the wort. The changes of pH during mashing process using tap and mineral water was studied. The lower acidity of wort obtained using mineral water didn’t change during the brewing process. The fluoride content of beer is lower than 5 mg.L-1 when wort is produced using mineral and tap water in 1:1 ratio and citric acid for pH correction. At the same time, the final degree of fermentation, α-amine nitrogen content and the intensity of color of produced wort are close to the control sample. The changes in fluoride ion concentration are monitored using ion-selective potentiometry. The fluoride content is decreased from 5.7 to 4.75 mg.L-1, the most intense change is observed during the mashing process.

This paper presents a study on the molybdenum blue reaction (MB) as a finishing detection step in soil analysis for quantification of plant available phosphorus. An ammonium acetate/calcium lactate reagent (pH = 4.2) was used for soil phosphorus extraction. The molybdenum blue color reaction using premixed Murphy-Riley reagent and ascorbic acid as a reductant was reinvestigated. UV-Vis characteristics of MB, optimal wavelength, reaction time and concentration of reductant were studied. The effect of ascorbic acid concentration and the reaction time on linearity, bias and uncertainty was discussed. The molybdenum blue reaction was found to obey Beer’s law in the targeted concentration range of 0.04 – 1.0 mg L-1 PO4 3--P. The linearity was proved by “lack-of-fit” test. The uncertainty budget was made and the uncertainty was estimated by modelling approach, as well as single laboratory and quality control approach. The recovery and the expanded uncertainty were found to be, respectively, (95.7 ± 8.7) % (P = 95 %, n = 3) and 9.2 mg PO4 ³--P /kg dry soil (k = 2). The results showed that the soil sample inhomogeneity and the repeatability of extraction process were the main factors which contribute to the uncertainty of measurement in soil analysis. [ABSTRACT FROM AUTHOR]

This study presented detailed evaluation of analytical characteristics of four advanced methods for total mercury quantification in aquatic biota samples. The method comparison as a validation strategy to ensure reliable and comparable results according to the ISO 17025 was presented. An analytical performance of the advanced mercury analyzer was compared with isotope dilution mass spectrometric measurements. Certified reference materials for mussel, oyster and scallop tissue were used during methods evaluation. The methods were then applied to unknown samples, such as Gammarus and Sea Bass samples. The highest values obtained for total mercury content in these samples was below maximum permissible limits: (0.222 ± 0.030) and (0.724 ± 0.022) mg kg-1. This comparative study could be of interest to laboratories for environmental monitoring or quality control of fishery products, as well as to other industries. [ABSTRACT FROM AUTHOR]