ИСТИНА

Gold nanoparticles (NPs) attract great attention in various fields of chemistry, physics and medicine. Unique optical properties of gold NPs are conditioned by the surface plasmon resonance (SPR). It results in intense absorbance band in the visible region and strong dependence of the band position on the NPs aggregation state. This phenomenon can be used for spectrophotometric determination of substances which affect the intensity or position of the SPR band. We have investigated the possibility of synthesis of polyurethane foam (PUF) modified with gold NPs and its application as a solid analytical form in diffuse reflectance spectroscopy for NPs formation/aggregation based determination of organic compounds. Two approaches to the synthesis of PUF modified with gold NPs have been suggested. One of them consists in NPs preparation in a solution followed by their sorption on PUF. Another one is based on NPs synthesis directly in PUF phase. An influence of different factors such as pH, time of the phase contact, concentration of NPs on their sorption on PUF was investigated. The quantitative sorption was achieved at pH 5 – 10 in 20 min. The spectral characteristics of PUF modified with NPs were investigated using diffuse reflectance spectroscopy. Mini-spectrophotometer Eye-One Pro (GretagMacbeth, Switzerland) was used. NPs aggregation in a solution induced by cetyltrimethylammonium bromide, polyhexamethyleneguanidine hydrochloride and melamine followed by sorption of NPs and their aggregates on PUF was investigated. It has been stated that the effect of SPR band decrease in diffuse reflectance spectra of the modified PUF can be used for determination of cetyltrimethylammonium bromide and polyhexamethyleneguanidine hydrochloride with detection limit 0.05 and 0.02 mg•L-1 respectively. The approach was applied for determination of polyhexamethyleneguanidine hydrochloride in disinfectant “Bior-1”. The test-method with controlled sensitivity for melamine detection has been suggested. Its sensitivity can be varied in the range 0.01 – 0.09 mg•L-1. Gold NPs synthesis directly in PUF matrix was performed by reduction of sorbed tetrachloroauric(III) acid with ascorbic acid. An influence of different factors on the yield of NPs was investigated. Intensity of SPR band in diffuse reflectance spectra of modified PUF linearly depends on concentration of ascorbic acid in the solution that can be used for its determination with detection limit 0.05 mg•L-1. The method was applied for analysis of vitamin form “Revit”. An ability of gold NPs to SPR together with stability, easy applicability, colourlessness, availability and low cost of PUF make this combination prospective for use as an analytical form in diffuse reflectance spectroscopy.