The conditional stability constants for various modifications of molybdenum heteropoly anions (HPAs) having Keggin structure were calculated using the results obtained when constructing the molar ratio curves. A comparative study of the stability of the main analytical forms of HPAs, which were used to determine phosphorus(V) and gallium(III), was carried out including oxidized, metal-substituted, reduced and oxidized forms, as well as those obtained in non-ionic surfactant medium. Based on the results of the study, molybdenum HPAs of phosphorus(V) can be arranged in the next row according to the values of conditional stability constant: PMo12O40 3-(in a non-ionic surfactant medium) (β = (1.60.6)•10 40) > H4РBi 3+ 2Mo4 V Mo7 VІ O40 6 (β = (5.61.6)•10 39) > H4РMo4 V Mo8 VІ O40 3-((β = 4.90.4)•10 37) > PMo12O40 3-(β = 10 36). The members of the series with n = 2-4 were the most stable in the series of gallium molybdotungsten HPAs. The stability of various forms of molybdenum HPAs of phosphorus(V) is not very different and is determined by the stability of the entire skeleton of Keggin heteropoly anion. When assessing overall stability of reduced forms of HPAs, it is important to consider their kinetic stability.

This article presents a study of monitoring the spread of antibiotic-resistant strains of sanitary-indicative microflora of food products sold on the consumer market of Dnipropetrovsk region. The increase of population in the world leads to an increase in the quality of livestock and poultry products. World experience shows that it is impossible to abandon the use of antibiotics in the rearing of pigs, cattle and poultry. Firstly, it is related to therapeutic and preventive measures in the fight against various diseases. Secondly, due to biochemical transformations in muscle fibers with the participation of antibiotics, consumer quality indicators (color, consistency) and technological quality indicators (moisture-absorbing and moisture-retaining ability) are improved. Therefore, livestock products can be one of the sources of sanitary microflora entering into the human body. In addition to the ability to cause an infectious process due to the synthesis of various pathogenic factors, including enzymes, toxins, adhesion substances, etc., in the sanitary-indicative microflora there is interstitial, intraspecific and intergeneric transfer of antibiotic resistance genes. This contributes to the emergence of cultures with acquired resistance to antibiotics and the formation of multi-resistant variants. Elimination of such strains from the human body will present certain difficulties. It was found that in the studied samples of milk and dairy products, as well as meat and offal of cattle and poultry, representatives of coliform bacteria, staphylococci and enterococci were less common. The isolated strains of sanitary-indicative microflora were the most resistant to ampicillin, oxacillin, tetracycline and doxycillin. 10 strains of S. aureus and 7 strains of S. epidermidiswas classified as MRSA and MRSE, respectively. Five of them were resistant to vancomycin and three to linezolid. Among the isolated cultures of enterococci were strains that were resistant to 5-6 or more drugs simultaneously. Of the bacteria of the family Enterobacteriaceae, the ability to synthesize extended-spectrum beta-lactamase (ESBL) was detected in 18 cultures, which accounted for 25.0 % of the total number of opportunistic enterobacteria. The ESBL strains of bacteria of the family Enterobacteriaceae differed from other isolates by resistance to at least 4 antibiotics, among which at least one belonged to the group of thirdgeneration cephalosporins. 7 strains of Escherichia coli, two strains of P. vulgaris and three strains of K. pneumoniae were characterized by resistance to 6 or more tested drugs.