Jacek Namiesnik

The role of speciation in analytical chemistry

The growing awareness of the strong dependence of the toxicity of heavy metals upon their chemical forms has led to an increasing interest in the qualitative and quantitative determination of specific metal species. Speciation has therefore become an important topic of present-day analytical research. This article describes the main types and areas of application of speciation analysis, and the use of sequential extraction in speciation studies. Brief characteristics of the basic types of speciation analysis, examples of their applications, and the usage of the various analytical techniques are also included.

Evaluation of the suitability of selected porous polymers for preconcentrations of volatile organic compounds

Abstract Breakthrough volumes on six porous polymers (Chromosorb 101, 103, 107 and Porapak N, Q, T) have been determined for vapours of 25 volatile organic compounds (amines, chlorinated hydrocarbons, etc.). The volumes were determined by a direct method, which seems to be simpler compared to the indirect estimation of breakthrough volume on the basis of such chromatographic parameters as retention volume, number of theoretical plates and peak width. The effect of the concentration of a model compound (acetone) in the gas mixtures on breakthrough volume was also determined on all investigated sorbents. The invetigations were carried out in a specially designed apparatus employing the method of diffusion tubes for the generation of model gaseous mixtures.

Preconcentration of Atmospheric Terpenes on Solid Sorbents

Abstract Hydrocarbons emitted by vegetation, such as isoprene and monoterpenes, seem to play an important role in atmospheric chemistry. A better estimation of their biogeochemical cycle requires that the levels be testable at any time. The extremely low concentration of these chemicals in the atmosphere necessitates a preconcentration step at the time of smpling. This enrichment was done on 13 solid adsorbents (Tenax GC and TA, Chromosorb 101, 103, 105 and 107, Porapak R and Q, XAD-2, 4 and 7, Ambersorb-XE-340 and Carbosphere). This study allowed us to determine the breakthrough volumes of isoprene and the principal monoterpenes on these adsorbents. Of the adsorbents tested, Tenax GC and TA were those the best adapted to the desorption of compounds as reactive as the terpenes.

Permeation Devices for the Preparation of Standard Gaseous Mixtures

SummaryTwo new permeation devices for generation of standard gaseous mixtures in wide concentration range have been designer. Teflon membranes and tubing have been utilized as the permeation barriers. The devices enable generation of multi-component mixtures.

Preconcentration of Volatile Sulphur Compounds on Solid Sorbents

Abstract The development of industry and urbanisation is at the origin of ever-increasing levels of anthropogenic pollution. Emissions of sulphur-containing compounds are partly composed of volatile organic compounds which add to those generated through natural processes. For low concentrations, direct assaying is problematic and a preconcentration step is necessary at the time of sampling. In order to select efficient solid sorbents for use in preconcentration of volatile organic sulphur-containing compounds, the breakthrough volumes of a certain number of mercaptans and sulphides have been determined on 9 porous polymers (Chromosorb 101, 103, 107,—Porapak Q, T, N,—XAD-4, XAD-7 and Tenax G.C.) and on Carbosphere. The breakthrough volumes were determined using a direct method with an apparatus based on diffusion tubes dynamically generating standard mixtures of carrier gas and sulphur-containing compounds.

AN AUTOMATED SPECIATION ANALYSER OF ORGANOMETALLIC COMPOUND CONTENT

This paper presents the design of an automated measurement device developed for speciation studies of organometallic compounds in samples of a complex and varying composition matrix. The instrument automates three essential steps in a typical speciation analysis procedure: isolation of analytes, their enrichment, and time-resolved introduction into a detector. Analytes are extracted by purging from post-sample dissolution/digestion mixture, in the form of volatile derivatives, with their simultaneous enrichment on a capillary cryotrap. Before introduction into a detector, they are rapidly (ca. 0.5 min.) separated on a multi-capillary gas chromatographic column operating in isothermal mode. The construction of the automated speciation analyser (ASA) makes it practically independent of a kind of the detector used (it was tested with MIP-AED,[1] ICP—MS,[2] and AAS detectors) and gives the freedom of choice of sample preparation procedure. The only requirement to the latter is that analytes should be in a form of volatile compound in an aqueous matrix.

Stabilization of a standard gas mixture generator with diffusion tubes

SummaryThe generator contains diffusion tubes of known length and internal diameter. Once produced, the mixture of the carrier gas and acetone, the reference material, is sent through a chromatographic flame ionisation detector. Its signal reaches a constant level after a time corresponding to the stabilization time of the generator. The technique described is simple and gives repeatable results.

Studies on the Use of Commercial Capillary Gas Chromatographic Columns as Diffusion Denuders

The possibility of using a piece of gas chromatographic capillary column as a tubular denuder for isolation and enrichment of organic pollutants present in air was studied. The partition coefficients (K ts ) of typical organic pollutants (benzene, chlorobenzene, toluene) between the gaseous phase and the denuder sorption layer were determined and effects of analyte concentration in the gaseous phase and gas flow rate on partitioning were studied. The partition coefficients were found to be constant in the studied range of concentration and gaseous mixture flow rate. A piece of a capillary column coated with polydimethylosiloxane can be used as a tubular denuder.