Rolandas Kazlauskas

Headspace extraction of alcohols into a single drop

The possibility of applying headspace microextraction into a single drop for the determination of alcohols in aqueous solutions is demonstrated. A drop of ethylene glycol containing butan-2-one as an internal standard is used for extraction. The analytes are extracted by suspending a 1 μl extracting drop directly from the tip of a microsyringe fixed above an extraction vial with a septum such that the needle passes through the septum and the needle tip appears above the surface of the solution. After the extraction is finished the drop is retracted back into the needle and injected directly into a GC column. Optimization of experimental conditions (sampling time, sampling temperature, stirring rate and ionic strength of the solution) with respect to the extraction efficiency were investigated and the linear range and the precision were examined. This headspace single drop microextraction method was applied to the analysis of beer.

AFM study of complement system assembly initiated by antigen-antibody complex

The shape and size of complement system C1 components assembled on a SiO2 surface after classical activation by antigen-antibody complex was determined by tapping mode atomic force microscopy (AFM). The SiO2 substrate was silanized and bovine leukemia virus proteins gp51 were covalently bound to the SiO2 substrate. Self-assembly of complement system proteins was investigated by AFM. Uniform coating of silanized surface by gp51 proteins was observed by AFM. After incubation of gp51 coated substrate in anti-gp51 antibody containing solution, Ag-Ab complexes were detected on the substrate surface by AFM. Then after treatment of Ag-Ab complex modified substrate by guinea-pig blood serum containing highly active complement system proteins for 3 minutes and 30 minutes features 2–3 times and 5–8 times higher in diameter and in height if compared with those observed after formation of Ag-Ab complex, were observed respectively on the surface of SiO2. This study revealed that AFM might be applied for the imaging of complement system assembly and provides valuable information that can be used to complement other well-established techniques.

Thermogravimetric analysis — a powerful tool for the refinement of the synthesis process of Hg-based superconductors

The paper presents the results of studies on thermogravimetric (TG) characterization of precursors and Hg-based superconductors synthesized by the sol-gel method. TG experiments were performed in an oxygen flow in order to understand the decomposition mechanisms of the fabricated gels and to determine the synthesis temperature of the intermediate precursors for the HgBa(2)CaCu(2)O(6+delta), HgBa(2)Ca(2)Cu(3)O(8+delta), and Hg(1-x)Tl(x)Ba(2)Ca(2)Cu(3)O(8+delta) superconductors. The optimum annealing temperature for a desired oxygen content in the superconducting compounds has been established by thermogravimetric measurements. To assist the interpretation of the obtained results the elemental analyses of the synthesized products were performed by AAS and EDS (SEM) methods.

Synthesis and evolution of crystalline garnet phases in Y3Sc5-xGaxO12

Mixed-metal oxides with the composition Y3Sc x Ga5− x O12 (x = 2.0, 2.1, 2.2, 2.25, 2.3, 2.4, 2.5, and 3.0) have been prepared by an aqueous sol–gel method. The effects of scandium substitution on the garnet phase formation were studied by IR spectroscopy and X-ray powder diffraction (XRD). The XRD data indicate that single-phase Y3Sc x Ga5− x O12 ceramic samples were obtained for x = 2.0, 2.1, 2.2, 2.25, 2.3, and 2.4. The results also show that the formation of Y3Sc x Ga5− x O12 garnets depends on the molar ratio of scandium and gallium in the investigated composition, and consequently on the mean cationic radius at the Al3+ sites. The variation of lattice parameters for the Y3Sc x Ga5− x O12 phases with different x is reported.

The current state of analytical control in Lithuania

In Lithuania research and development in chemical analysis are concentrated in scientific institutes and universities. The main fields of interest focus on biosensors, electrochemical sensors, sampling techniques and methods, study of atomization processes in spectrochemical analysis and noise evaluation in analytical measurements. Some laboratories also take part in international environmental monitoring programmes. There are about 50 researchers at the Ph.D. level engaged in analytical chemistry and several hundred technicians specialized in the field of analytical control. About one hundred chemical laboratories are active in scientific institutes, universities and factories. Specialized laboratories of chemical analysis are at the disposal of Environmental Control and Health Protection Departments and forensic investigation organizations. So far no laboratories are accredited according to the ISO 9000 norms. Special courses on analytical chemistry are offered at a few schools of higher education in the country. Only at the Department of Analytical Chemistry of the University of Vilnius specialized programmes are available to postgraduate students working towards a Ph.D. to improve their skills in current techniques of analytical chemistry. Recently the Technical Committee TC-16 for Chemical Analysis was formed within the standardization system of Lithuania. Its main activities are centered on issues such as national terminology, certified reference materials (CRMs), analytical methods and analytical quality assurance. There are numerous problems related to national terminology, the preparation of special documents in the field of analytical control and the production of regional environmental CRMs. Problems, also arise in obtaining and using CRMs for analytical instrument calibration and validation.