The Nanostructure Studies of Surfactant-Free-Microemulsions in Fragrance Tinctures.

As it was shown recently that nanostructures can exist in water-ethanol-citronellol tinctures, a deeper investigation of these media was performed using conductivity, UV-Vis and FT-IR spectroscopy techniques. Different regimes of conductivity, depending on the water content, an increase of the polarity of the polar pseudo-phase with increasing water content, and even the presence of free water molecules at higher water content are observed, just as in classical surfactant-based microemulsions. The percolation model, generally used to fit conductivity data in surfactant based microemulsion having a weak interfacial film, can be used to fit our conductivity data below a critical water content Φ(p)(w) with a critical exponent typical of dynamic percolation.

Flow injection spectrophotometric determination of N-acetyl-L-cysteine as a complex with palladium(II).

We describe a new method using flow-injection analysis with spectro-photometric detection, suitable for the determination of N-acetyl-L-cysteine (NAC). The proposed method is appropriate for the determination of NAC in reaction with Pd(2+) ions in the concentration range from 1.0 × 10(-5) mol L(-1) to 6.

Determination of coenzyme A (CoASH) in the presence of different thiols by using flow-injection with a UV/Vis spectrophotometric detector and potentiometric determination of CoASH using an iodide ISE.

Coenzyme A (CoA or CoASH) is one of the most important biologically active compounds, and for this reason a reliable, fast and simple determination of CoASH is needed. Here we are described a simple and fast way of determinating CoASH using potentiometric flow-injection analysis and spectrophotometric kinetic determination. The described methods are suitable for use over a wide concentration range (1 x 10(-6)-1 x 10(-4) M) of CoASH.