Chromatography–mass spectrometry identification of polyaromatic hydrocarbons in thermally modified petroleum products and thermal destruction products of organic materials of various origins

Polyaromatic hydrocarbons in samples of thermally treated petroleum products and thermal destruction products of organic materials of various origins are studied. Samples of kerosene, diesel fuel, and gasoline of different grades, that is, light flammable petroleum products often used as combustion initiators; wood; flooring (linoleum); and offset paper are selected as test samples. A pattern for determining these samples by chromatography–mass spectrometry against the background of other products formed under fire conditions is developed. It is suggested to use the limiting value of the intensity ratios of the peaks of tri- and bicyclic condensed arenes in trace residues of the combustion initiator, modified as a result of evaporation and burnup, as an identification parameter. This approach expands the range of tasks in identifying the source of environmental pollution and in determining traces of combustion initiator for forensic and fire-technical expertise.     

Determination of Ketosteroids in Human Urine Using Dispersive Liquid-Liquid Microextraction and Ultra High-Performance Liquid Chromatography-High Resolution Mass Spectrometry

Journal of Analytical Chemistry - A method is proposed for the determination of some ketosteroids in human urine, including enzymatic hydrolysis using β-glucuronidase from E. coli followed by...     

Kinetics of Extraction of Biologically Active Substances from Medicinal Plant Raw Materials using Different Techniques

The problems and peculiarities of obtaining the kinetic characteristics of extraction of biologically active substances (BAS) from a plant matrix are discussed. The establishment of kinetic characteristics of the extraction of BAS under various extraction conditions is studied on the example of samples of Hypericum perforatum and Salvia officinalis. The lowest value of the average rate constant of the extraction of BAS from the materials examined is characteristic of a variant of static extraction with an aqueous alcohol extractant under heating. The methods of static extraction under heating (according to the requirements of pharmacopoeia articles) and ultrasonication, as well as using double ultrasonication differ little from each other in their kinetic efficiency. The method of dynamic extraction of BAS at an elevated temperature and pressure is characterized by the highest values of the rate constant, which leads to an acceleration of the diffusion of the BAS into the extractant’s medium. It is noted that the extraction processes and chemical transformations of some BAS (hyperforin, carnosic acid, etc.) occur simultaneously as confirmed by the decrease in their concentrations in the extractant during the extraction from plant samples.     

Determination of Andarine (S-4), a Selective Androgen Receptor Modulator,and Ibutamoren (MK-677), a Nonpeptide Growth Hormone Secretagogue,in Urine by Ultra-High Performance Liquid Chromatography with Tandem Mass-Spectrometric Detection

A procedure for the determination of a selective androgen receptor modulator andarine (S-4) and a nonpeptide growth hormone secretagogue ibutamoren (MK-677) in urine has been developed including sample preparation by the “dilute-and-shoot” procedure, separation of analytes by ultra-high performance liquid chromatography in the gradient elution mode, and mass-spectrometric detection with heated electrospray ionization. The limits of detection are in the range of 0.5–2.5 ng/mL, the calibration curves are linear in the range of 2.5–250 ng/mL for andarine and 5–250 ng/mL for ibutamoren. The proposed procedure was used for the analysis of urine samples obtained from volunteers after a single administration of these drugs containing 15 mg of active substances.     

Some aspects of estimation of extraction selectivity under the conditions of competitive sorption on modified silica gels

Systematic studies of silica gels with covalently immobilized thiosemicarbazide and formazan groups under the conditions of competitive sorption from multicomponent systems were conducted. A methodological approach to determine the selectivity of the modified sorption material with regard to Cu(II), Ni(II), Co(II), Cd(II), and Zn(II) was proposed. Solid-phase extraction in equilibrium conditions of Cu(II), Zn(II), Co(II), Cd(II), and Ni(II) on a silica gel with covalently immobilized thiosemicarbazide and formazan groups in the conditions of competitive sorption was studied. The possibility to use the pseudo-second-order kinetic equation for assessment of mutual influence at competitive sorption has been shown. We found that sorption from multicomponent solutions proceeds as a non-additive process under the conditions of an excess of functional groups.

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Chemometric Estimation of the Contributions of Metals and Volatile Compounds to the Sensory Properties of Some Natural Grape Wines

Journal of Analytical Chemistry - Based on the concentrations of metals and volatile compounds in red and white wine samples and using linear and general linear models, we performed a comparative...