Analysis of Cadmium and Cadmium Oxide by Inductively Coupled Plasma Atomic Emission Spectrometry

A procedure of the multielement analysis of cadmium and cadmium oxide by inductively coupled plasma atomic emission spectrometry is proposed. The effect of the concentration of the matrix component on the analytical signals of impurity elements is studied and the analytical lines of the analytes are chosen. For the chosen concentration of the matrix component, the optimum conditions of analysis are selected, i.e., power delivered to the plasma and the flow rate of sputtering argon gas. The accuracy of the developed procedure, ensuring the determination of up to 41 impurity elements with limits of detection in the range from n × 10^–7 to n × 10^–4 wt %, is estimated.     

Investigations in the field of benzazoles and naphthazoles

1-(Alkyl benzimidazolyl)-, 1-benzothiazolyl- and 1-benzoxazolyl-3-methyl-5-phenylformazans containing sulfo groups (in the meta or para position) in the phenyl residue have been synthesized. It has been established that some of them can be used as analytical reagents.For part XXI, see [5].     

Solid-phase mechanochemical synthesis of zirconium tetracarboxylates

The solid-phase synthesis of zirconium carboxylates Zr(OOCR)₄ (R = Alk) by reactions of zirconium tetrachloride with metal carboxylates (isobutyrate, pivalate, and palmitate) (the molar ratio ZrCl₄: RCOOM is 1: (4–5)) under mechanical activation is developed. Further thermal treatment of the reaction mixture and extraction with an organic solvent afford zirconium carboxylates.     

Modified fluororubbers based on SKF-26: Relaxation and mechanical properties

Samples of SKF-26 fluororubber modified by incorporating pendant methoxy groups into the macromolecular chain were studied by dielectric spectroscopy and dynamic mechanical analysis.     

p-Terphenyl as unexpected by-product in the synthesis of 2,5-diphenylpyrrole from acetophenone oxime and phenylacetylene

Russian Journal of Organic Chemistry -     

Sorption Selectivity of Palladium(II) by Poly(N-2-Sulfoethylallylamine) under Static and Dynamic Conditions

Russian Journal of Applied Chemistry - The process of Pd(II) sorption from hydrochloric acid solutions was studied in the pH range of 0.5–5.0 in the presence of Pt(IV) and a number of...     

Molecular Characteristics and Antioxidant Activity of Spruce (Picea abies) Hemicelluloses Isolated by Catalytic Oxidative Delignification

Spruce (Picea abies) wood hemicelluloses have been obtained by the noncatalytic and catalytic oxidative delignification in the acetic acid-water-hydrogen peroxide medium in a processing time of 3–4 h and temperatures of 90–100 °C. In the catalytic process, the H₂SO₄, MnSO₄, TiO₂, and (NH₄)₆Mo₇O₂₄ catalysts have been used. A polysaccharide yield of up to 11.7 wt% has been found. The hemicellulose composition and structure have been studied by a complex of physicochemical methods, including gas and gel permeation chromatography, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. The galactose:mannose:glucose:arabinose:xylose monomeric units in a ratio of 5:3:2:1:1 have been identified in the hemicelluloses by gas chromatography. Using gel permeation chromatography, the weight average molar mass M_w of hemicelluloses has been found to attain 47,654 g/mol in noncatalytic delignification and up to 42,793 g/mol in catalytic delignification. Based on the same technique, a method for determining the α and k parameters of the Mark–Kuhn–Houwink equation for hemicelluloses has been developed; it has been established that these parameters change between 0.33–1.01 and 1.57–472.17, respectively, depending on the catalyst concentration and process temperature and time. Moreover, the FTIR spectra of the hemicellulose samples contain all the bands characteristic of heteropolysaccharides, specifically, 1069 cm⁻¹ (C–O–C and C–O–H), 1738 cm⁻¹ (ester C=O), 1375 cm⁻¹ (–C–CH₃), 1243 cm⁻¹ (–C–O–), etc. It has been determined by the thermogravimetric analysis that the hemicelluloses isolated from spruce wood are resistant to heating to temperatures of up to ~100 °C and, upon further heating, start destructing at an increasing rate. The antioxidant activity of the hemicelluloses has been examined using the compounds simulating the 2,2-diphenyl-2-picrylhydrazyl free radicals.     

Identification of Organic Volatile Markers Associated with Aroma during Maturation of Strawberry Fruits

In the present study, organic volatile markers of three strawberry varieties (Albion, Festival and Frontera) during the maturation process were investigated. Forty metabolites associated with aroma in fresh strawberries were monitored during seven stages of maturation using gas chromatography–mass spectrometry (GC-MS) equipped with headspace-solid phase microextraction (HS-SPME). The data were evaluated using multivariate analysis to observe correlations between the organic volatile compound profile and the seven phenological stages of maturation for each strawberry variety. The dynamic levels of butanoic acid methyl ester, hexanoic acid methyl ester, octylcyclohexane, cyclohexane,1,1,2-trimethyl, linalool, tetradecane, and α-muurolene underwent distinctive changes in concentration during the maturation process. The multivariate analysis also allowed the identification of these compounds as possible volatile markers to measure the maturation of strawberry fruits in all three varieties. These findings highlight the importance of the timing of harvest and maturation stage in each variety to preserve or improve the desirable aromatic characteristics of strawberry fruits.     

Enhanced Physical and Mechanical Properties of Nitrile-Butadiene Rubber Composites with N-Cetylpyridinium Bromide-Carbon Black

The physical and mechanical properties of nitrile–butadiene rubber (NBR) composites with N-cetylpyridinium bromide-carbon black (CPB-CB) were investigated. Addition of 5 parts per hundred rubber (phr) of CPB-CB into NBR improved the tensile strength by 124%, vulcanization rate by 41%, shore hardness by 15%, and decreased the volumetric wear by 7% compared to those of the base rubber-CB composite.