T. A. Kuchmenko

Using a multi-sensor gas analyzer for investigating the change in the aroma of an Agar matrix with natural ingredients

The adsorption of a mixture of highly volatile compounds, vapors found in the equilibrium gas phase of natural fruits and berries, on thin films of adsorbents was studied using a multi-sensor gas analyzer “piezoelectronic nose”. Polyethylene glycol adipate, polyethylene glycol sebacate, polystyrene, dicyclohex-ane-18-crown-6 ether were used as sorbents. Changes in the composition of the equilibrium gas phase upon the formation of the aromatic composition of an agar matrix with natural ingredients and the storage and spoilage of the product were revealed. A test method allowing the detection the first signs of the microbiological spoilage of the product was developed to assess the drift in the aroma of jelly confectionery containing various natural fruits (orange, apple), berries (blueberry, blackberry, cowberry, cranberry, sour cherry), and lemon and orange peel.

Detection of synthetic components in food matrices using piezoelectric resonators

The adsorption of a mixture of volatile components from the vapor phase of synthetic flavoring agents on thin adsorbent films was studied using piezoelectric quartz microweighing. Conventional gas-chromatographic adsorbents and specific films of different nature were used as adsorbents. It was shown that synthetic flavoring agents, including those used in the production of foodstuffs, can be identified and their quality can be assessed. The use of an array of piezoelectric quartz microbalances with various films allowed the slightest changes in the composition of the equilibrium vapor phase of synthetic flavoring agents to be recorded. An algorithm using a universal database on piezoelectric quartz microweighing of flavoring agent vapors was proposed for detecting them in food products and revealing adulterations.

Determination of trace amounts of hydrogen sulfide in a gas flow using a piezoelectric detector

The following parameters are substantiated and optimized in the detection of H2S in a gas flow: the nature and flow rate of the carrier gas; the qualitative and quantitative composition of a sensing coating; the technique of its application onto the electrodes of a piezoelectric detector; and the geometrical parameters (volume and configuration) of a flow detecting cell. A testing unit for detecting H2S in the range from 3 to 18 mg/m3 is developed on the basis of a modified piezoelectric resonator with high frequency characteristics (13–16 MHz).

Sensor Analysis of Gases Emitted in Basic Organic Synthesis

A matrix comprised of eight different sensors based on piezoelectric-crystal resonators was used for analysis of multicomponent gas mixtures. The resonator electrodes were modified with both known and unconventional gas-chromatographic sorbents.

Sorption of Acetone and Phenol on Natural Film Coatings of Electrodes of a Bulk Acoustic Wave Piezoelectric Resonator

The sorption–desorption of acetone and phenol on thin-film coatings of electrodes of bulk acoustic wave piezoelectric resonators was studied. Natural materials (bee-glue and beeswax) were used as natural coatings. The sorption activity of the coatings was determined along with their sorption selectivity and stability for the analytical application of modified bulk acoustic wave piezoelectric sensors in the detection of acetone and phenol in the air.

Solvent Effect on the Sensitivity and Selectivity of Determining Aniline and Toluidines in the Air by Piezoelectric Microweighing

Batch conditions were optimized for the sorption of aniline and toluidines from the air on polystyrene, polyethyleneglycol-2000, and polyethyleneglycol succinate using piezoelectric microweighing. It was found that the analytical signal of a quartz crystal resonator depended on the mass of the modifier on the electrode surface and on the solvent. The selectivity of modifiers with respect to the compounds studied was estimated.

Use of piezosensors for determining the composition of the equilibrium gas phase of aqueous protein solutions

Possibility of using modified piezosensors to determine the composition of multicomponent gas mixtures was studied. The sorption conditions of readily volatile components of aqueous protein solutions on modifier films of varied nature for piezoquartz resonators were examined and optimized. A set of methods for determining aroma-forming components of complex mixtures was developed. The possibility of using the methods developed for determining the nature of aroma-forming additives to milk drinks was demonstrated.

Effect of solvent on the adsorption of benzene vapors by dicyclohexane-18-crown-6 thin films

The solvent effect on the stability of the zero signal of resonators with a dicyclohexane-18-crown-6 film was studied. The adsorption capacity and sensitivity of the film coatings to benzene vapors was estimated. The performance characteristics of the microweighing of benzene vapors were calculated. A model was proposed for benzene adsorption from the gas phase on thin films of crown ether.

Determination of C1-C3 carboxylic acids in air using a sensor

The adsorption of C1-C3 carboxylic acids on modified films of different natures and polarities is studied in exposuring piezoelectric sensors to acid vapors. The method of film fabrication and the ratio of components in the mixed films are optimized; the sensitivity and selectivity of films are calculated; piezoelectric sensors are proposed for the separate determination of acids in air; and equations for calculating their concentrations are derived.

Determination of formic and acetic acids in air by piezoelectric microweighing

The quantitative and kinetic parameters of sorption of formic and acetic acids on thin films of various modifiers of piezoelectric quartz resonator electrodes are determined. Parameters of film formation on the electrodes (application procedure and thickness) are optimized. Methods for joint and separate determination of formic and acetic acids in air by piezoelectric microweighing with single- and double-sensor devices are developed.