Sulfonamide drugs: Low-cost spectrofluorometric determination using a computer monitor calibrator for detection.

A possibility of the use of a common monitor calibrator as a portable and inexpensive tool for the fluorometric determination of sulfonamide drugs after their reaction with fluorescamine was examined. The luminescence measurements with a calibrator are based on irradiation of a test sample by the device lamp with a broadband spectrum in the visible and near UV regions and simultaneous registration of the secondary radiation by the device detector. Two types of cuvettes with black light absorbing sides eliminating the reflected self-radiation were tested. The commercially available Eppendorf-type black plastic microtubes ("LightSafe") were suggested as a good option for such measurements. It was shown that a monitor calibrator can be applied for optimization of the determination conditions. By the example of sulfanilamide and sulfamethazine, it was shown that the procedure should be carried out at pH 4-6 and fluorescamine concentration of 200 µmol L-1, and 40 min of the interaction. The limit of detection of sulfanilamide and sulfamethazine using a monitor calibrator is 0.9 µmol L-1 and 0.8 µmol L-1, respectively, which is comparable with their spectrophotometric determination.

Towards the development of solid-state platform optical sensors: aggregation of gold nanoparticles on polyurethane foam.

In this paper, we report on a novel type of nanocomposites based on gold nanoparticles (AuNPs) and polyurethane foam (PUF), which represents an ability of AuNP aggregation on solid polymer matrix with the strongly different selectivity in comparison with aggregation of the same AuNPs in solution. This may indicate that a new type of aggregation takes place, which can be called solid-phase aggregation. A systematic study using diffuse reflectance spectroscopy revealed features of the solid-phase aggregation. The PUF-AuNPs nanocomposites can be synthesized by a simple and low cost procedure based on adsorption of different type AuNPs from aqueous solution onto PUF. Prospects of obtained composite materials for sensing some organic compounds using diffuse reflectance spectroscopy or colorimetry are shown. This nanocomposites have the increased selectivity to thiols allowing for their determination with limits of detection of 0.01-0.05µgmL-1 and relative standard deviations of 3-5%. Charged species that affect AuNPs in solution do not influence them on PUF.