Biomedical subjects

A Przyjazny

Publications and source records attributed to A Przyjazny.

8 recordsLinked to original sources

PubMed2006

Techniques of preparing plant material for chromatographic separation and analysis.

This paper discusses preparation techniques of samples of plant material for chromatographic analysis. Individual steps of the procedures used in sample preparation, including sample collection from the environment or from tissue cultures, drying, comminution, homogenization, leaching, extraction, distillation and condensation, analyte enrichment, and obtaining the final extracts for chromatographic analysis are discussed. The techniques most often used for isolation of analytes from homogenized plant material, i.e., Soxhlet extraction, ultrasonic solvent extraction (sonication), accelerated solvent extraction, microwave-assisted extraction, supercritical-fluid extraction, steam distillation, as well as membrane processes are emphasized. Sorptive methods of sample enrichment and removal of interferences, i.e., solid-phase extraction, and solid-phase micro-extraction are also discussed.

Chromatography↗

PubMed2006

Procedure for and results of simultaneous determination of aromatic hydrocarbons and fatty acid methyl esters in diesel fuels by high performance liquid chromatography.

The content of aromatic hydrocarbons in diesel fuels is regulated by appropriate standards, and a further reduction in the allowed concentration of these hazardous substances in these fuels is expected. The content of aromatic hydrocarbons in diesel fuels is most often determined using standard methods EN-12916 or ASTM D-6591. The content of polycyclic aromatic hydrocarbons (PAHs) is determined from a single peak obtained using normal phase high-performance liquid chromatography (NP-HPLC), a column of the NH2 type, n-heptane as the eluent, refractive index detector (RID) and backflushing of the eluent. However, the methods mentioned above cannot be applied when the fuel contains fatty acid methyl esters (FAME), which lately has become more common. The content of FAME in diesel oils is determined using mid-IR spectrophotometry based on the absorption of carbonyl group. However, no standard procedure for the determination of classes of aromatic hydrocarbons in diesel fuels containing FAME is yet available. The present work describes such a modification of methods EN-12916/ASTM D-6591 that provides a simultaneous determination of individual groups of aromatic hydrocarbons, total content of polycyclic aromatic hydrocarbons and the FAME content in diesel fuels. The refractive index detector (RID) and n-heptane as the mobile phase are still used, but backflushing of the eluent is applied after the elution of all polycyclic aromatic hydrocarbons. Additionally, ultraviolet diode array detection is used for the exact determination of low contents of polycyclic aromatic hydrocarbons and to confirm the presence of FAME in the analyzed fuel.

Calibration↗

PubMed2006

Chemometrics in monitoring spatial and temporal variations in drinking water quality.

This case study reports multivariate techniques applied for the evaluation of temporal/spatial variations and interpretation of monitoring data obtained by the determination of chloro/bromo disinfection by-products in drinking water at 12 locations in the Gdańsk area (Poland), over the period 1993-2000. The complex data matrix (1756 observations) was treated with various multivariate techniques. Cluster analysis (CA) was successful, yielding two different groups of similarity reflecting different types of drinking water supplied (surface and groundwater). The locations supplied in general with groundwater could be further classified into two subgroups, depending on whether the groundwater was mixed with surface water or not. Analysis of variance (ANOVA) was used to classify and thus confirm the groups found by means of cluster analysis and proved the existence of statistically significant differences between the concentration levels of CHCl3, CHBrCl2+C2HCl3, CHBr2Cl, and CH2Cl2 in the samples collected. Of all the variables evaluated, only three were characterized by statistically significant correlations (CHCl3, CHBrCl2+C2HCl3, CHBr2Cl). The analysis of correlation coefficients revealed that chloroform formed as the main chlorinated disinfection by-product and, furthermore, the natural presence of bromide in water (both ground and surface) results in the formation of brominated disinfection by-products (DBPs). Temporal variations of volatile organic chlorinated compounds (VOCls) were also evaluated by multidimensional ANOVA. Observation of temporal changes in the concentration of VOCls at the location supplied with both surface and groundwater reveals a steady improvement in drinking water quality. In general, the study shows the importance of drinking water monitoring in connection with simple but powerful statistical tools to better understand spatial and temporal variations in water quality.

Cluster Analysis↗

PubMed1999

Changes in concentration levels of selected VOCs in newly erected and remodelled building in Gdansk.

Volatile organic compounds such as benzene, toluene, butyl acetate, ethylbenzene, m-xylene, styrene and m-dichlorobenzene were measured in three newly erected and remodelled dwellings. The present study also attempted to examine the time dependence of concentrations of selected VOCs in each investigated dwelling. This was accomplished by at least triplicate measurements of the IAQ. To collect a series of air samples the active and passive methods were used. In both cases activated charcoal was applied as a sorption medium. The samples were recovered by solvent extraction, and analysed by capillary column gas chromatography, employing a flame ionisation detector. The experimental results showed that MAC values for analysed VOCs were exceeded (even a few orders of magnitude) for the measurements made before inhabiting of the occupants, in every investigated dwelling. The concentrations of the investigated VOCs decreased significantly with time, which should be expected, although in some cases the levels of selected VOCs remained still high. Our experience indicates that parallel application of two different indoor air sampling techniques to determine analytes of interest, though more laborious and time consuming, can lead to significant conclusions concerning indoor air quality in monitored spaces.

Air Pollution, Indoor↗

PubMed1999

Passive dosimetry as an alternative technique to dynamic enrichment of organic pollutants of indoor air.

Evaluation of the quality of indoor air was carried out in 20 apartments, 3 offices, and 3 laboratories in the Tricity area in Poland with reference to concentrations of selected volatile organic compounds (VOCs), such as benzene, toluene, butyl acetate, ethylbenzene, m-xylene, styrene, and m-dichlorobenzene. The time dependence of concentrations of selected VOCs in a newly erected building was studied. Two different techniques were used for the isolation and preconcentration of analytes from air samples: a passive method employing a home-made permeation-type passive sampler and a dynamic method based on a sorption tube. In both cases, activated charcoal was used as a sorption medium (trap packing). The sorption tube was used to validate the results obtained by the passive method, as well. In the majority of dwellings examined, the concentrations of air pollutants were relatively low and did not exceed the MAC values. No significant differences were observed between MAC concentrations determined by using the passive or the dynamic method of air sampling. The results obtained by both sampling methods were characterized by similar precision.

Air Pollutants↗

PubMed1996

Occurrence and determination of pesticides in natural and treated waters.

Pesticides as environmental pollutants are described in detail along with their sources and paths of entry into various elements of the environment. Comprehensive literature data on the concentration of these pollutants in natural and treated waters and wastewaters are discussed. A wide selection of isolation and preconcentration techniques for these pollutants in water is presented and discussed. An emphasis is put on solid-phase extraction. In the case of the authors' work, a more detailed description is given.

Humans↗

PubMed1993

Sensitive and selective liquid chromatographic postcolumn reaction detection system for biotin and biocytin using a homogeneous fluorophore-linked assay.

A homogeneous fluorophore-linked assay was used to develop a postcolumn reaction detection system for high-performance liquid chromatography (HPLC). Biotin and biocytin were chosen as the model analytes. The effluent from the HPLC column was merged with a reagent stream containing avidin that was labeled with fluorescein isothiocyanate (avidin-FITC). The binding of the separated analytes by the labeled avidin was accompanied by an enhancement of the fluorescence intensity at 520 nm. This increase in fluorescence was proportional to the concentration of the analytes and constituted the analytical signal. The procedure was optimized with respect to the reagent concentration and the flow-rate of the reagent solution. Analytical characteristics of the method were determined. The procedure was highly selective for biotin and its derivatives. The detection limits for biotin and biocytin were 89 and 94 pg, respectively, for 20-microliters injections. The developed postcolumn reaction detection system was validated by determining biotin in a liquid vitamin preparation and a horse-feed supplement.

Avidin↗

PubMed1990

High-performance liquid chromatographic postcolumn reaction detection based on a competitive binding system.

Postcolumn reactions are typically employed to improve detection in high-performance liquid chromatography (HPLC) separation techniques. This study proposes the use of competitive binding principles in designing novel postcolumn reaction schemes. The feasibility of this approach was tested by using the HPLC determination of biotin and biocytin as a model system. The effluent from the HPLC column was merged with a reagent stream containing avidin, whose binding sites were occupied by the dye HABA (2-[4'-hydroxyphenylazo]benzoic acid). HABA was displaced by the analytes from the avidin-HABA complex and the free dye was determined with a UV-vis detector at 345 nm. The procedure was optimized with respect to reactor design, reagent concentrations, and the flow rate of reagent solution. Analytical characteristics of the developed procedure were determined and compared with the direct detection of biotin and biocytin at 220 nm. The postcolumn reaction scheme improved the selectivity and sensitivity of the detection of biotin and biocytin while maintaining similar detection limits.

Azo Compounds↗