FIELD: microbiology. SUBSTANCE: invention relates to industrial products - liquid detergents, aqueous-emulsion dyes, domestic deodorants, an aqueous-base gels, agents for personal hygiene and others. The 1-st variant of composition slowing down bacteria growth: dimethyloldimethylhydantoin, monomethylol-dimethylhydantoin, dimethylhydantoin 20-40 wt.-% at mass ratio dimethyloldimethylhydantoin : monomethyldimethylhydantoin = (1:1.25)-(3.5: 1). Total formaldehyde content is 10-25 wt.-% and content of free formaldehyde is less 0.1 wt.-%. Composition is an aqueous solution. The 2-d variant: an anhydrous composition has dimethyloldimethylhydantoin (20-40 wt.-%), monomethyloldimethylhydantoin and dimethylhydantoin at mass ratio dimethyloldimethylhydantoin : monomethyloldimethylhydantoin = (1:1.25)-(3.5:1). Total formaldehyde content is 10-20 wt.-% and content of free formaldehyde is less 0.1 wt.-%. The 3-d variant: an anhydrous composition obtained by interaction of dimethylhydantoin and formaldehyde-containing source at mole ratio formaldehyde : dimethylhydantoin = (1.2:1)-(1.55:1). Methods of preparing compositions involve the following stages: a) interaction of dimethylhydantoin with formaldehyde source is carried out at mole ratio formaldehyde : dimethylhydantoin = (1.2-1.55):1; b) interaction of dimethylhydantoin with formaldehyde source is carried out at mole ratio formaldehyde : dimethylhydantoin = (1.3-1.55):1; c) interaction of dimethylhydantoin with formaldehyde an aqueous solution (pH = 8-9) is carried out. Mole ratio formaldehyde : dimethylhydantoin = (1.3-1.55):1 and pH value of obtained product is brought about to 6.5-7.5 followed by its heating to 44-55 C for 2.5-3.5 h, cooling to the room temperature and pH value is brought about to 6.8-7.2; d) an aqueous solution of monomethyloldimethylhydantoin containing above 0.1 wt.-% formaldehyde is mixed with dimethylhydantoin at mass ratio = (80-90)-(10-20). Method of bacteria growth slowing down involves mixing biocidically effective amount of composition with medium where bacteria can grow. Invention ensures to decrease free formaldehyde content to less 0.1 wt.-%, retain its antibacterial property stability. This ensures to exclude unwanted properties, for example, nonfavorable odor, skin irritation, hazard for health. EFFECT: prolonged span-life of preparations exhibiting sensitivity to bacteria effect, improved quality and effectiveness of compositions. 22 cl, 10 tbl, 31 ex
