Ernst Lankmayr

Occurrence of triazines in surface and drinking water of Liaoning Province in Eastern China.

The Liaoning Province in Eastern China has a prosperous economy and traditional agricultural background. Steadily increasing water demand implies the direct use of surface water for drinking water support and foodstuff production. Due to the extensive use, high persistence, water solubility and relatively weak adsorptivity, the chloro s-triazines contaminate the aquatic environment and are therefore regularly and most frequently detected in ground and surface water. Water sample enrichment procedures were performed by solid-phase extraction (SPE) using different materials. During a 1-year monitoring program on the Liao-He River, water sample enrichment was performed using C(18)-SPE cartridges. These SPE cartridges showed low recoveries for the atrazine metabolites, although high triazine values were detected. Based on these results, a pilot sampling on drinking water in the Liao-He region was performed. This time, in addition to the C(18)-SPE cartridges, a new polymer SPE sorbent made from a balance ratio of two monomers, the lipophilic divinylbenzene and the hydrophilic N-vinylpyrrolidone, was used. Both materials were characterized by establishing breakthrough curves for the investigated analytes and up to large volumes.

Determination of d-penicillamine in serum by fluorescence derivatization and liquid column chromatography

A simple and fast method for the determination of D-penicillamine in serum is described. The analysis is based o a fluorescence derivatization of the sulfhydryl group combined with a reversed-phase liquid chromatograhic separation and fluorescence detection. Before derivatization the serum proteins are precipitated with ethanol and removed by centrifugation. As derivatizing agent 5-dimethylaminonaphthaline-1-sulfonylaziridine is used which reacts selectively with thiols under defined reaction conditions. The detection limit is in the pmol range; 50-300 ng of D-penicillamine can be determined with a relative standard deviation of 7-8%. Thus the method permits a simple determination of D-penicillamine in serum at therapeutic levels.

Triazines in the aquatic systems of the Eastern Chinese Rivers Liao-He and Yangtse

The results of a one-year monitoring program on the two Eastern Chinese River systems, i.e. the Liao-He and the Yangtse, with special emphasis on the presence of triazine herbicides are presented. Sediment, suspended solids and water samples from both rivers were analyzed. Additionally, recovery experiments on the SPE-in-field-enrichment procedure and the extraction methods were performed. The samples were measured by gas chromatography coupled with mass spectrometry, electron capture detection and a newly developed mu-plasma atomic emission detector. A typical result of a one-year monitoring was obtained in case of the Liao-He: During winter, at low water period, low triazine values were found. A similar situation was found in early spring. Highest concentrations of atrazine up to 1600 ng/l were found in late spring in the water samples. Maximum concentrations of atrazine, simazine, propazine, simetryn and prometryn were observed in this season as a result of the actual use of triazines. Finally, after the high water period in autumn the triazine concentrations decreased. Additionally, atrazine adsorbed on sediment (up to 2.8 ng/g) and suspended solids was determined (up to 8 ng/l) during late spring sampling. Therefore, the logarithm of the organic carbon based sorption coefficient of atrazine could be calculated. Low levels of atrazine were measured in the water of Yangtse (up to 18.3 ng/l). The concentrations from all sampling points and sampling stations of a particular sampling date were similar, which indicates a homogeneous distribution of this herbicide. Due to the high discharge rate of up to 79,000 m3/s in case of the Yangtse a considerable mass transport of up to 57.5 kg per day atrazine may take place, even at concentrations below the European drinking water limit of 100 ng/l.

Polycyclic aromatic hydrocarbons in the environment: high-performance liquid chromatography using chemically modified columns

Abstract A simple and rapid procedure for the separation and determination of a number of polycyclic aromatic hydrocarbons (PAHs) in environmental dust samples is described. An ultrasonic extraction method was used to separate the organic compounds from the dust particles. Only small amounts of dust and solvents are needed and the extraction requires only a few minutes. Compounds that would interfere in UV detection after high-performance liquid chromatography (HPLC) are separated from the aromatic fraction by preparative thin-layer chromatography on silica gel. The chromatographic behaviour of the carcinogenic hydrocarbons on several stationary phases in HPLC was investigated. A comparison of the chromatographic data showed that silica gel chemically modified with NO 2 groups gives the best selectivity. Nanogram amounts of PAHs were easily detected by using a UV monitor.

Microwave-assisted derivatization of volatile carbonyl compounds with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine.

A method for the determination of carbonyl compounds, either directly from gaseous phase or following a volatilization from liquid or solid samples after trapping on Tenax TA is presented. Following solvent desorption, the carbonyls are derivatized using O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine. The reaction is accomplished in a microwave oven using closed vessels to minimize reaction time compared to conventional methodology. The solvent for the chemical reaction was selected according to the requirements of microwave energy interaction and solubility. After gas chromatographic separation of the corresponding oximes, they are detected using electron impact mass spectrometry in single ion monitoring mode. Quantification is carried out using internal standardization with 3-fluorobenzaldehyde, resulting in limits of detection in the ppm range following the calibration graph method. The optimized conditions provide for good recoveries and fast reaction rates for the volatile carbonyls studied so far.

A chromatographic response function for automated optimization of separations

SummaryA chromatographic response function is studied that is sensitive to important criteria of analytical performance: selectivity, accuracy, precision and time required to perform the separation. This function can be applied to mixtures of unknown solutes and little computational effort is needed to evaluate the numerical value of the function from the chromatogram. It shows well defined optima at elution strengths that give minimal elution times simultaneously with good separations in high-performance liquid chromatography. No prior chromatographic information characterizing the expected performance of a system is required. It is possible to use this function without a mechanistic model describing the separation process.

Separation of enantiomeric iodinated thyronines by liquid chromatography of diastereomers.

A method for the separation of D,L-triiodothyronine and D,L-tetraiodothyronine optical isomers is described. The iodinated thyronines are coupled with L-leucine and the resulting diastereomers are separated by reversed-phase liquid chromatography. The derivatives are detected in the UV region at 230 nm. The technique can be used for the determination of the optical purity of thyroid hormones. It is possible to determine 0.2% of the L-isomer in D-tetraiodothyronine with a relative standard deviation of 8%. One complete analysis takes about 2 h. The results are in good agreement with those of an enzymatic method.

Optimized extraction of polycyclic aromatic hydrocarbons from contaminated soil samples

A comparison of Soxhlet extraction and a new extraction technique, fluidized-bed extraction, has been conducted. The extraction of polycyclic aromatic hydrocarbons (PAHs) by this new technique has been optimized considering as experimental variables the variation of the number of extraction cycles and the holding time after reaching the heating temperature by means of a surface response design. The significance of the operational parameters of the fluidized-bed extraction onto the performance characteristics has been investigated. For the determination of the analytes, a cleanup of the extracts followed by gas chromatography with mass spectrometric detection was used. The accuracy of the method was established by extraction and analysis of a reference material, supplied from the European Commissions Joint Research Centre.

Elimination of matrix effects for static headspace analysis of ethanol

The intention of this work was to develop a simple and fast procedure for a determination of small amounts of ethanol in aqueous protein containing solutions based on combined headspace gas chromatography. In order to provide for short analysis time static headspace methodology was considered for this purpose. In this context the influence of the matrix composition onto the analytical results has been established and internal standardization as well as a full evaporation technique have been evaluated as promising alternatives for a compensation of matrix effects. With respect to speed of analysis, simplicity of sample handling as well as the quality of the analytical performance parameters, precision and accuracy, the full evaporation technique proved to be superior. Thus, the static equilibration of a 20 microliters sample aliquot in a conventional headspace sample vial for 5 min at 100 degrees C is sufficient to obtain equilibrium conditions for gas chromatographic analysis. The accuracy of this method was verified by robust regression analysis and exhibited excellent robustness within the required limits of sample composition ranging from 0 to 20% (w/w) protein content and up to 5 g/l salt content.

Analysis of Sulfonated Compounds by Reversed-Phase Ion-Pair Chromatography - Mass Spectrometry with On-Line Removal of Non-Volatile Tetrabutyl Ammonium Ion-Pairing Agents

SummaryAn ion-pair reversed-phase high performance liquid chromatography method with tetrabutyl ammonium salts as ion-pairing agents and mass spectrometric detection has been developed for sulfonated compounds with special focus on structural identification.A cation exchange suppressor cartridge placed between the UV detector and the ion source of the mass spectrometer completely removed the non-volatile ion-pairing agent resulting in excellent conditions for both electrospray ioniziation and atmospheric pressure chemical ioniziation. Peak broadening caused by the dead volume of the suppressor is negligible.The application range of this method is demonstrated by the structural identification of individual compounds within a complex mixture of model substances consisting of sulfonated aromatics, textile dyes and detergents with as many as four sulfonic acid groups, all largely differing from each other in their structural properties. The influence of the ion-pairing agents counter ion on retention behaviour is also discussed.