Waldemar Wardencki

Problems with the determination of environmental sulphur compounds by gas chromatography

The occurrence of environmental sulphur species, which are significant biogenic and antropopogenic pollutants of the atmosphere, and some problems with their gas chromatographic determinations are reviewed. Techniques most frequently applied for their sampling from gas and liquid matrices, as well as preconcentration or isolation methods are discussed. The problems encountered in chromatographic analysis of sulphur-containing compounds, including chromatographic columns and detection systems, are also described. The simple procedures of avoiding the losses and transformations of these compounds during storage, sampling and analysis (e.g., oxidant removal, silanization) are briefly presented.

Food Analysis Using Artificial Senses

Nowadays, consumers are paying great attention to the characteristics of food such as smell, taste, and appearance. This motivates scientists to imitate human senses using devices known as electronic senses. These include electronic noses, electronic tongues, and computer vision. Thanks to the utilization of various sensors and methods of signal analysis, artificial senses are widely applied in food analysis for process monitoring and determining the quality and authenticity of foods. This paper summarizes achievements in the field of artificial senses. It includes a brief history of these systems, descriptions of most commonly used sensors (conductometric, potentiometric, amperometic/voltammetric, impedimetric, colorimetric, piezoelectric), data analysis methods (for example, artificial neural network (ANN), principal component analysis (PCA), model CIE L*a*b*), and application of artificial senses to food analysis, in particular quality control, authenticity and falsification assessment, and monitoring of production processes.

Evaluation of headspace solid-phase microextraction for the analysis of volatile carbonyl compounds in spirits and alcoholic beverages

A method was developed for the determination of C1-C6 carbonyl compounds in alcoholic solutions using pentafluorobenzoxymation followed by headspace sampling solid-phase microextraction and subsequent analysis by GC with electron-capture detection. Experimental conditions-alcohol content, exposure time, temperature and sample agitation were optimised. In this method, a spirit or distilled alcoholic beverage is first adjusted to 20% (v/v) alcohol. Detection limits for particular aldehydes and ketone varied from 0.05 to 0.5 microg/l and relative standard deviation was between 2.3 and 20%. Generally, the method showed good linearity for the tested concentration range 8 microg/l-0.32 mg/l with regression coefficients ranging between 0.9434 and 0.9983. The method was applied to the analysis of real alcoholic beverages (vodkas).

Invited review article: an odor-sensing system--powerful technique for foodstuff studies.

This work examines gas sensor array technology combined with multivariate data processing methods and demonstrates a promising potential for rapid, non-destructive analysis of food. Main attention is focused on detailed description of sensor used in e-nose instruments, construction, and principle of operation of these systems. Moreover, this paper briefly reviews the progress in the field of artificial olfaction and future trends in electronic nose technology, namely, e-nose based on mass spectrometry. Further discussion concerns a comparison of artificial nose with gas chromatography-olfactometry and the application of e-nose instruments in different areas of food industry.

Solventless Sample Preparation Techniques in Environmental Analysis

This review focuses on the role of so-called solventless methods of sample preparation in contemporary environmental analysis. The basic classification of this group of methods as well as the principal features and advantages of the techniques in current use are discussed.

Gas chromatographic sulphur-sensitive detectors in environmental analysis

Abstract Gas chromatographic (GC) detection systems, which are especially suited for the selective determination of sulphur compounds in various matrices, and their applications are reviewed. They include flame photometric, electron-capture, chemiluminescence, atomic emission, electrochemical and photoionization detectors. The principles of operation, characteristics and development and compatibility with capillary columns are briefly described. The possibility of coupling with supercritical fluid chromatography, liquid chromatography and some spectroscopic techniques is discussed

Application of an Electronic Nose Instrument to Fast Classification of Polish Honey Types

The paper presents practical utilization of an electronic nose prototype, based on the FIGARO semiconductor sensors, in fast classification of Polish honey types—acacia flower, linden flower, rape, buckwheat and honeydew ones. A set of thermostating modules of the prototype provided gradient temperature characteristics of barbotage-prepared gas mixtures and stable measurement conditions. Three chemometric data analysis methods were employed for the honey samples classification: principal component analysis (PCA), linear discriminant analysis (LDA) and cluster analysis (CA) with the furthest neighbour method. The investigation confirmed usefulness of this type of instrument in correct classification of all aforementioned honey types. In order to provide optimum measurement conditions during honey samples classification the following parameters were selected: volumetric flow rate of carrier gas—15 L/h, barbotage temperature—35 °C, time of sensor signal acquisition since barbotage process onset—60 s. Chemometric analysis allowed discrimination of three honey types using PCA and CA and all five honey types with LDA. The reproducibility of 96% of the results was within the range 4.9%–8.6% CV.

Simple device for permeation removal of water vapour from purge gases in the determination of volatile organic compounds in aqueous samples

Abstract A commercially available Nafion tube (a perfluorinated ion-exchange resin membrane separator) inserted in a plastic container filled with 5A molecular sieve was tested on dry water-saturated gas streams containing common volatile pollutants of aqueous environmental samples after a purging cycle. The proposed device was shown to remove water vapour effectively from humidified gas streams ( > 90%) even under continuous operation for more than 10 days. The results showed that the system is compatible with the tested compounds (aliphatic and aromatic hydrocarbons, chlorinated hydrocarbons and some sulphur compounds) because these compounds are practically unaffected on passing through the Nafion dryer tube. The losses of most compounds at the μg/kg level are less than 5%. Therefore, the proposed device is suitable for the removal of water vapour from purging streams and can be used in the determination of these volatile organic compounds in aqueous samples using the purge-and-trap technique.

Analytical Techniques Used in Monitoring of Atmospheric Air Pollutants

The air pollution monitoring is one of the most pressing environmental problems today. The paper describes common air pollutants, their interaction and impact on the environment, and classifies the techniques and methods applied in air studies. Furthermore, the review characterizes the selected collection and sampling techniques used for gas sample analysis. Finally, the schematic diagrams of typical designs of systems applied in such studies are presented.

Determination of volatile fatty acid ethyl esters in raw spirits using solid phase microextraction and gas chromatography

An analytical method for the determination of fatty acid ethyl esters in raw spirits of different quality or produced from various raw materials has been developed and optimized. A combination of headspace solid phase microextraction (HS-SPME) as the extraction technique and gas chromatography with flame ionization detection (GC-FID) as the determination technique was utilized. HS-SPME conditions such as: type of the stationary phase of the fiber, ethanol content, sample volume, extraction temperature and time, salt addition and sample agitation were investigated to determine the most suitable conditions for the analysis of volatile fatty acid ethyl esters in raw spirits. The quantification method was an internal standardization using methyl octanoate as the internal standard. The methods detection limits (MDLs) for the individual ethyl esters ranged from 26.8 to 0.0470 microg L(-1) 20% EtOH. The feasibility of SPME for the quantitative analysis of fatty acid ethyl esters in raw spirits of different organoleptic quality was demonstrated. High precision and simple sample preparation enable the use of this method for routine investigations in both industrial and research laboratories.