Andrzej Przyjazny

Single drop microextraction—Development, applications and future trends

Single drop microextraction (SDME) has emerged over the last 10-15 years as one of the simplest and most easily implemented forms of micro-scale sample cleanup and preconcentration. In the most common arrangement, an ordinary chromatography syringe is used to suspend microliter quantities of extracting solvent either directly immersed in the sample, or in the headspace above the sample. The same syringe is then used to introduce the solvent and extracted analytes into the chromatography system for identification and/or quantitation. This review article summarizes the historical development and various modes of the technique, some theoretical and practical aspects, recent trends and selected applications.

Analytical characteristics of the determination of benzene, toluene, ethylbenzene and xylenes in water by headspace solvent microextraction

Headspace solvent microextraction (HSM) is a novel method of sample preparation for chromatographic analysis. It involves exposing a microdrop of high-boiling point organic solvent extruded from the needle tip of a gas chromatographic syringe to the headspace above a sample. Volatile organic compounds are extracted and concentrated in the microdrop. Next, the microdrop is retracted into the microsyringe and injected directly into the chromatograph. HSM has a number of advantages, including renewable drop (no sample carryover), low cost, simplicity and ease of use, short time of analysis, high sensitivity and low detection limits, good precision, minimal solvent use, and no need for instrument modification. This paper presents analytical characteristics of HSM as applied to the determination of benzene, toluene, ethylbenzene and xylenes in water.

Analytical Applications of Membrane Extraction for Biomedical and Environmental Liquid Sample Preparation

A review of the membrane extraction methods used in determination of various organic compounds in liquid environmental matrices and biological fluids is presented. Theory and principles, possibility of combining membrane extraction methods with methods of final determination, and applications are discussed in detail.

Utilization of standards generated in the process of thermal decomposition chemically modified silica gel for a single point calibration of a GC/FID system

The utilization of a multicomponent gaseous standard mixture, containing CO and CO(2) and obtained by thermal decomposition of a so-called immobilized compound, for a single point calibration of a GC/FID system are described. The generation of such a mixture takes place as a result of thermal decomposition of a sample of chemically modified silica gel placed in a heated chamber of thermal desorber coupled with the device being calibrated via a catalytic methanizer. The mean amount of the analyte librated from unit mass of the gel was 0.71 mg g(-1) (RSD = 3%) for carbon monoxide and 0.86 mg g(-1) (RSD = 3%) for carbon dioxide.

Headspace microdrop analysis—an alternative test method for gasoline diluent and benzene, toluene, ethylbenzene and xylenes in used engine oils

The primary standard test method used for the determination of gasoline diluent in used engine oils is method D 3525-93 of the American Society for Testing and Materials (ASTM), which involves direct injection of used oil onto a packed GC column and flame ionization detection. Recently, we have utilized a new headspace sampling method: headspace solvent microextraction (HSM), for GC and GC-MS analysis of gasoline diluent in used engine oils. High resolution capillary columns can be used without the necessity for the use of inlet cryogenic cooling or expensive sampling interfaces. This analytical method, which we generically refer to as headspace microdrop analysis yields results comparable to those obtained using the ASTM method, with the added benefit that it allows the quantification of individual volatile diluent components, including benzene, toluene, ethylbenzene and the xylenes.

Progress in Development of Molecularly Imprinted Polymers as Sorbents for Sample Preparation

Sample preparation has been one of the most often investigated steps in analytical procedures. These investigations are focused on problems such as isolation of analytes from the sample matrix, matrix simplification, analyte enrichment to the level above the detection limit of the instrumentation used, and the removal of interfering species to improve the final determination. Techniques based on solid (adsorption) and pseudo liquid (absorption) media play an important role in sample preparation because of their universal applicability, possibility of automation and low cost of implementation. The use of these techniques reduces or even completely eliminates organic solvents from analytical procedures. Solid phase extraction (SPE) and its special mode, solid phase micro-extraction (SPME), are among most commonly used sample preparation techniques. The search for novel sorbents characterized by their unique sorption properties aims at expanding the applicability of SPE and SPME. One of such novel groups of sorbents are molecularly imprinted polymers—MIPs. The purpose of this paper is to review recent publications on synthesis and applications of MIPs as well the procedures used to study MIPs.

Application of Passive Samplers in Monitoring of Organic Constituents of Air

The principles of passive dosimetry, which has been known for over 100 years, are finding an ever increasing use in analytical practice and are being used as a convenient technique for isolation and enrichment of analytes from various environmental media. Due to its simplicity, a variety of designs, as well as the possibility of using a number of different final determination techniques, passive dosimetry has been applied in the analysis of organic and inorganic air pollutants, both in the outdoor and the indoor and workplace atmospheres, as well as in the monitoring of water and soil pollution. This paper is an attempt to review the designs of existing passive samplers, the media used to trap analytes and the techniques used for the release of the trapped analytes and their final determination.

Biological Fluids as a Source of Information on the Exposure of Man to Environmental Chemical Agents

The human body is exposed to a variety of environmental pollutants. Many chemical compounds, including volatile organochlorine compounds and metals, have a harmful effect on the tissues and organs of the human body, in many cases causing irreversible damage and illnesses. In order to assess the degree of occupational hazard, it has become more and more common to determine the concentrations of chemical substances or their metabolites in biological fluids (i.e., in urine, blood, or less often, in human milk, bile, saliva, and sperm). However, in order to determine concentrations levels of trace components in biological fluids such as urine, blood, milk, bile, saliva, or sperm, the samples collected have to be prepared for the final analysis because their matrix is so complex as to preclude direct determination of the analytes by any analytical method available. This article contains the literature data on: analyte isolation and/or enrichment techniques from samples of biological fluids prior to the final determination step; and final determination techniques for a variety of compounds, both organic and inorganic, being determined in the above samples. The data include both the primary pollutants that found their way into the human body as a result of environmental and occupational exposure and the products of their conversion (metabolism) in the organism.

Characteristics of volatile organic compounds emission profiles from hot road bitumens.

A procedure for the investigation and comparison of volatile organic compounds (VOCs) emission profiles to the atmosphere from road bitumens with various degrees of oxidation is proposed. The procedure makes use of headspace analysis and gas chromatography with universal as well as selective detection, including gas chromatography-mass spectrometry (GC-MS). The studies revealed that so-called vacuum residue, which is the main component of the charge, contains variable VOC concentrations, from trace to relatively high ones, depending on the extent of thermal cracking in the boiler of the vacuum distillation column. The VOC content in the oxidation product, so-called oxidized paving bitumen, is similarly varied. There are major differences in VOC emission profiles between vacuum residue and oxidized bitumens undergoing thermal cracking. The VOC content in oxidized bitumens, which did not undergo thermal cracking, increases with the degree of oxidation of bitumens. The studies revealed that the total VOC content increases from about 120 ppm for the raw vacuum residue to about 1900 ppm for so-called bitumen 35/50. The amount of volatile sulfur compounds (VSCs) in the volatile fraction of fumes of oxidized bitumens increases with the degree of oxidation of bitumen and constitutes from 0.34% to 3.66% (w/w). The contribution of volatile nitrogen compounds (VNCs) to total VOC content remains constant for the investigated types of bitumens (from 0.16 to 0.28% (w/w) of total VOCs). The results of these studies can also find use during the selection of appropriate bitumen additives to minimize their malodorousness. The obtained data append the existing knowledge on VOC emission from oxidized bitumens. They should be included in reports on the environmental impact of facilities in which hot bitumen binders are used.

Synthesis of sol-gel mesoporous silica materials providing a slow release of doxorubicin

Samples of mesoporous base-catalysed silica xerogel materials made by the sol-gel process were impregnated with an anticancer drug—doxorubicin, followed by different times of ageing at room temperature. The effect of ageing time on the physical and structural properties as well as sorption–desorption of the drug was investigated. The obtained results suggest an inverse relationship with a solid density and surface area increasing as the pore size and volume decrease during ageing time. These results also revealed the effect of ageing time on the efficiency of sorption–desorption of the drug. An increase in ageing time results in an increase of the efficiency of drug sorption and a decrease in the rate of drug release.