Miroslav Fišera

Preconcentration of platinum group metals on modified silicagel and their determination by inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry in airborne particulates

Modified silicagel (C18) was studied for separation and preconcentration of platinum group metals (Ru, Rh, Pd, Os, Ir and Pt) as ion associates of their chlorocomplexes with cation of onium salt N(1-carbaethoxypentadecyl)-trimethyl ammonium bromide. Sample containing HCl and the onium salt was pumped through the column. After elution with ethanol the eluate was evaporated in the presence of HCl. Resulting aqueous solutions were analysed with inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). Recovery values of 1-20 mug Pt and Pd from 50 ml of synthetic pure solution were 100+/-3 and 100+/-1%, respectively, however, they diminished with increasing sample volume and in the presence of the real sample matrix or nitrate ions. Samples of engine soot (NIES No. 8), decomposed by low pressure oxygen high-frequency plasma, and airborne particulates from dust filters of meteorological stations, leached with HNO(3) and H(2)O(2), were analysed. A reasonable agreement was found between ICP-MS and ICP-AES results for airborne dust samples and the values comparable with those in literature were determined in NIES No. 8.

Biosorption of Cadmium Ions by Different Yeast Species

Toxicity and accumulation of Cd2+ in yeasts were studied in eight different yeast species. The adaptation to toxic concentration of this metal was dependent on the production of extracellular yeast glycoproteins. The highest concentration of Cd2+ ions in the growth medium was tolerated by a Hansenula anomala, strain while the lowest tolerance was found by the strain of species Saccharomyces cerevisiae. Extracellular glycoproteins of Hansenula anomala absorbed nearly 90% of the total content of Cd2+ ions bound by yeast cells, while extracellular glycoproteins of Saccharomyces cerevisiae bound only 6% of the total amount of cadmium. This difference is caused by the variable composition of the saccharide moiety in the extracellular glycoproteins. The composition of extracellular glycoproteins changed during the adaptation of the yeast cells to the presence of Cd2+ ions.

Determination of mercury in concentrated mineral acids by electrothermal atomic absorption spectrometry using gold amalgamation

A method for the determination of trace amounts of mercury in concentrated hydrochloric, sulphuric and phosphoric acids by atomic absorption spectrometry at the p.p.b. level has been developed. After reduction of inorganic mercury compounds to mercury vapour, the vapour is transported by an inert gas from the solution and trapped on the gold coated wall of a graphite cuvette. In the second step of the determination, the absorbance signal from the atomisation of mercury released from the amalgam is measured. Peak height and area are both proportional to the mercury level between 5 and 100 p.p.b. with an RSD of up to 15%. Solutions of NaBH4 or SnII were used as reducing agents.

Total polyphenolic compounds contents (TPC), total antioxidant activities (TAA) and HPLC determination of individual polyphenolic compounds in selected Moravian and Austrian wines

AbstractWine samples (Grüner Veltliner (GV) and Zweigelt (ZW) from four different geographical regions of Austria and Czech Republic) were analyzed to determine their total phenolic content (TPC) by applying the Folin-Ciocalteau method, total antioxidant activity (TAA) by FRAP (ferric reducing antioxidant power) and DPPH (1,1-diphenyl-2-picryl-hydrazyl) assays, and to identify and quantify eleven phenolic compounds using a HPLC/UV-VIS method.

Determination of trace impurities in high-purity graphite by electrothermal atomic absorption spectrometry and inductively coupled plasma atomic emission spectrometry

The process for the determination of B and Si in high-purity graphite used for spectral analysis elaborated here, is based on matrix combustion without any loss of analyte in an oxygen atmosphere with the addition of alkali. Sub-boiling distilled nitric acid and water were used to dissolve ashes. Silicon, B, Cd and Cu were determined by inductively coupled plasma atomic emission spectrometry and the other elements (Cr, Co, Mo, V, Ni and Ti) were determined by electrothermal atomic absorption spectrometry. Carbon is the most commonly used material in the production of electrodes for emission spectral analysis as well as being the material of electrothermal atomizers used in atomic absorption analysis. The level of impurity should not be greater than 10–5–10–6%. The purifying processes used in the production of carbon electrodes for spectroscopy are adequate for obtaining these values for most elements, with the exception of B, Si and those elements whose carbides are extremely non-reactive. Precision, given as the relative standard deviation for both Si and B at the ppm level was within 10%. The accuracy of the whole procedure was controlled using spiked samples.

Characterisation of metal-binding biomolecules in the clam Chamelea gallina by bidimensional liquid chromatography with in series UV and ICP-MS detection

The presence of metal-binding biomolecules has been studied in Chamelea gallina, a bioindicator used for environmental contamination monitoring and very popular for human consumption in the Atlantic southwest coast of Spain. This area is affected by metal pollution from mining activities, which can modify biomolecules expression in this bivalve. Total content of elements was determined by ICP-MS and revealed a remarked presence of Fe, Zn, Cu, As and Mn. A metallomics approach has been optimised for this mollusc using size-exclusion chromatography on column Superdex 30 pg HiLoad 26/60 with in series UV and ICP-MS detection. At least four fractions with molecular weight in the range 1540 to 415 Da were observed with UV detection, but the ICP-MS chromatogram showed the presence of metals of interest only in the first two fractions. The apparent molecular weights of these metal-containing fractions were from 1325 to 764 Da. The fractions containing metals compounds were collected and lyophilised for further purification of reconstituted extracts with a second orthogonal chromatographic separation using reverse phase (RP) HPLC with ICP-MS detection. Several peaks were obtained in this second dimension separation which allows the isolation of As-, Cu- and Zn-containing biomolecules.

In Vitro Digestibility of Different Commercial Edible Algae Products

Digestibility is an important factor in determining the level of nutritive factors utilization. Determination of in vitro digestibility in a Daisy incubator and assessment of protein digestibility using Kjeldahl method of algal food products after pepsin, pancreatin, and combined hydrolysis of both enzymes was described. The influence of different hydrolysis times on algal digestibility was investigated in brown seaweeds, red seaweeds, and green alga. The highest digestibility values were generally determined in red seaweeds after 24 h of combined hydrolysis by pepsin and pancreatin. Direct dependence between digestion time and digestion efficiency was verified and statistically proven.

Interaction of polyphenols and wine antioxidants with its sulfur dioxide preservative

Wine is considered to be a significant alcoholic beverage, which is the result of fermentation of grape must or mash. Wine is a must when the substances contained in it play a major role, which are essential inhibiting water, carbohydrates, acids, minerals, nitrates, polyphenols and aromatics. These biochemical components are an important tracking element in wine evaluation in terms of chemical analyzes. An important parameter of monitoring is polyphenolic substances. Polyphenol substances are identified in plant materials as several thousand pieces with a very diverse structure. However, they have a common feature up to one or more aromatic rings substituted with hydroxyl groups. These substances may be present in plant material in a small or large amount. The total daily intake of polyphenols is estimated at 1 g. This is a higher intake than antioxidant vitamin intakes and it is confirmed that their antioxidant activity is higher than that of antioxidant vitamins. When monitoring the content of all polyphenols (TPC) in selected samples using a spectrophotometric method, a higher TPC content of red wines against white white wines can be observed. Total antioxidant activity is introduced to compare antioxidant effects of different mixtures and is based on the ability to eliminate radicals. Antioxidant activity and effects of polyphenols can be inhibited by the addition of preservatives to wine. The preservative is sulfur dioxide (SO2), which has antimicrobial and antioxidant effects. This compound is not harmless because it is a strong allergen, blocks bacteria in the digestive tract and prevents the conversion of sugars and alcohol derivatives in the liver by blocking vitamin B. In the normal life, SO2 is consumed under the E 220 mark. The aim of this work is to monitor the change in the total polyphenols content related to free and bound sulfur dioxide (SO2) content using accredited OIV-MA-AS323-O4B: R, 2009 samples in wine samples. Comparison of organic wines and wines produced by classical, it was found that organic wine have a higher content of biologically active substances and have a strong correlation factor TAA total SO2 (r = 0.77 to 0.91), depending on the wine variety.

Whole-Cell Protein Profiles of Disintegrated Freshwater Green Algae and Cyanobacterium

ABSTRACT The influence of cultivation methods and postharvesting treatment on protein profiles of green freshwater microalgae Chlorella kessleri, Scenedesmus quadricauda, and Chlorella sp. and cyanobacterium Spirulina platensis were evaluated. The comparison of protein profiles in algal biomass originated from the autotrophic cultivation in an outdoor open circulating cascade-type cultivation apparatus in thin-layer, a solar photobioreactor, and from the heterotrophic cultivation regime in a fermenter. All tested algae contained protein bands in the area between 14.3–27 and 70–116 kDa. Protein profiles revealed much higher heterogenity in the area between 30–70 kDa.

Influence of composition of feed and lactation period on mineral composition of Mare's

Effects of lactation period and feed on essential minerals composition of mares milk were studied. Average Ca, P, Na and Mg concentrations in feed DM were 0.66, 4.30, 0.13 and 2.21 g.kg-1 of DM (dry matter), respectively. In regard to milk all elements concentrations were not similar to each other due to the changes of the lactation day differences. Average Ca, P, Na and Mg concentrations (in DM) caused by breed differences and lactation days were 1.95, 1.08, 0.53 and 0.22 g.kg-1, respectively. During the milk period, a high-quality feed were maintaining the major mineral composition of mares milk in 1.5 - 2 times higher amount than milk of mare fed with pasture and a low-quality feed. The colostrum stage of mare was much shorter than other animals, the mares milk on the 2nd day of lactation showed properties of initial milk in which its composition, particularly in minerals, were two times higher when compare to that on milk periods that was started from 5th day after parturition. It seemed that some factors, except well physiological conditions, such as mares age, number of foaling, sex of foal etc. did not affect milk nutrient composition.