Michiel Ceulemans

Integrated sample preparation and speciation analysis for the simultaneous determination of methylated species of tin, lead and mercury in water by purge-and-trap injection-capillary gas chromatography-atomic emission spectrometry

A sensitive and interference-free automated method for the simultaneous speciation analysis of methylated species of mercury, tin and lead, and also inorganic mercury in water, using purge-and-trap injection–gas chromatography–atomic emission spectrometry, was developed. The ionic species are volatilized from the sample after ethylation, using sodium tetraethylborate, in acetate buffer medium of pH 5 and preconcentrated on a capillary cryogenic trap. Desorption is effected by linear heating of the trap, followed by separation of the analytes by capillary gas chromatography and selective simultaneous detection by microwave-induced plasma atomic emission spectrometry. Detection limits of 0.15, 0.20 and 0.60 ng l–1 for methylated tin, lead and mercury species, respectively, and 2 ng l–1 for inorganic mercury can be obtained, on the basis of a 10 ml sample volume. Examples of results for the analysis of river- and soil run-off water samples are given.

Flow-injection sample preparation for organotin speciation analysis of water by capillary gas chromatography-microwave-induced plasma atomic emission spectrometry

A semi-automated flow-injection system was developed for on-line sample preparation for the determination of mono-, di- and tributyl- and phenyltin compounds in water. The procedure is based on the preconcentration of ionic organotin compounds by sorption on bonded silica with octadecyl functional groups followed by on-column ethylation using sodium tetraethylborate. The derivatized species are eluted with 250 μl of methanol, separated by gas chromatography and detected with a microwave-induced plasma atomic emission detector. Aliquots of 25 μl of the eluate are introduced on to a capillary column using the cool injection technique. The solvent is vented off in the liner before the temperature of the latter is raised to release the analytes. A 10–50 ml water sample is sufficient for the analysis and a detection limit of 0.1 ng 1−1 can be obtained. The developed procedure was applied to the determination of organotin compounds in a number of river water samples which were analysed in parallel using a manual liquid-liquid extraction procedure. The results agreed within 10–15% for concentrations of a few ng 1−1.

Evaluation of sample preparation methods for organotin speciation analysis in sediments — focus on monobutyltin extraction

Two sample preparation procedures, based on different leaching, extraction, complexing and derivatization conditions, for the analysis of butyltin compounds in sediment samples are evaluated and compared. Particular emphasis is given to factors affecting monobutyltin extraction efficiency. The validity of both methods is demonstrated by the analysis of the available reference materials. Two independent hyphenated techniques, gas chromatography interfaced with atomic emission spectrometry and atomic absorption spectrometry, are used for independent confirmation of analytical results. Applications for the analysis of sediments, sampled from Belgian harbours and drydocks are shown.

Rapid sensitive speciation analysis of butyl- and phenyltin compounds in water by capillary gas chromatography atomic emission spectrometry (GC-AES) after in-situ ethylation and in-liner preconcentration

SummaryA rapid, simple and sensitive method has been developed for the simultaneous determination of butyl- and phenyltin species in environmental waters. The ionic organotin compounds are ethylated in the aqueous phase using sodium tetraethylborate (NaBEt4) and extracted with hexane. A 25 μl aliquot of the extract is injected at a low temperature into a Tenax filled liner. After solvent venting the analytes are transferred onto the capillary column using programmed temperature vaporization (PTV) injection. Detection is done by means of a microwave induced plasma atomic emission detector (MIP AED). The method allows the determination of butyl- and phenyltin compounds in water samples down to the level of 0.1 ng/l (as Sn) while 50 ml of sample is sufficient for analysis. The accuracy of the method was confirmed by GC-AAS after chelation and Grignard derivatization.

Microwave-accelerated speciation analysis for butyltin compounds in sediments and biomaterials by large volume injection capillary gas chromatography quartz furnace atomic absorption spectrometry

A method for speciation analysis of butyltins in sediments and biomaterials by capillary GC with atomic absorption spectrometric detection was developed. Mono-, di- and tributyltin in sediments were quantitatively leached with 50% acetic acid, whereas biomaterials were dissolved in a 25% tetramethyl ammonium hydroxide (TMAH) solution; both processes were completed under the action of a low-power focused microwave field within 1–5 min which is 20–100 times faster than with conventional procedures. The butyltins were derivatized with sodium tetraethylborate (NaBEt4) in the aqueous phase, and simultaneously extracted into hexane (5 min). On-line preconcentration in the injector liner by solvent venting enabled to obtain a detection limit of 5 ng g−1 for 0.2 g of dry sample. A sample throughput of 5 samples h−1 was achieved. The method developed was validated by analyzing three certified reference materials: PACS-1, CRM 462 and NIES 11.

Evaluation of a purge-and-trap injection system for capillary gas chromatography-microwave induced plasma-atomic emission spectrometry for the determination of volatile selenium compounds in water

A method is presented for the selective determination of the volatile selenium species dimethylselenide and dimethyldiselenide, using a commercially available purge-and-trap injection system coupled to capillary gas chromatography-microwave induced plasma-atomic emission spectrometry. The efficiency of the purging step was evaluated and the parameters affecting the purge and trap processes were optimized. The method was applied to the determination of volatile selenium compounds in lake water. Relative detection limits of 2ng/l for dimethylselenide and dimethyldiselenide, corresponding to an absolute detection limit of 10 pg, were achieved.

Speciation Analysis Of Organotin In The River Scheldt By Capillary Gas Chromatography Atomic Emission Spectrometry (Gc-Aes)

Abstract Two rapid, sensitive and interference-free analytical procedures were developed for the comprehensive speciation analysis of ionic butyl- and phenyltin compounds in water. One of them based on ethylation of ionic organotin in the aqueous phase with sodium tetraethylborate (NaBEt4) followed by the extraction of the derivatized species into hexane. The other method involved preconcentration of ionic organotin on a C18 cartridge followed by on-column ethylation in a semi-automated flow system. Separation and determination of organotin species were performed by capillary gas chromatography with microwave induced plasma atomic emission detection (GC-MIP AED). 20–50 ml of sample was sufficient for the analysis and a detection limit of 0.1 ng/l (as Sn) was obtained. The methods were applied to the determination of organotin in the river Scheldt at 15 locations close to the Antwerp agglomeration. Butyltin compounds were detected in all the analyzed samples at concentrations ranging between 10–140 ng/l, 8...

Determination of methyl- and butylin compounds in waters of the Antwerp harbour

Abstract Ionic methyltin and butylin compounds were determined in dockwater of the harbour of Antwerp (Belgium) in order to evaluate the emission and distribution of organotin species discharged during dry dock activities. Speciation analysis was performed by gas chromatography-quartz furnace atomic absorption spectrometry (GC-QFAAS) and gas chromatography with atomic emission detection (GC-AED) after enrichment by extraction of the analytes as the corresponding diethyldithiocarbamate (DDTC) complexes into pentane and pentylation of the extracted analytes with Grignard reagent. Concentrations of dimethyltin (DMT), monomethyltin (MMT), tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT), varied between 0.74 and 5; 0.88 and 10; 1.83 and 443; 1.45 and 120; 1.08 and 38 ng·l−1 at various locations and sampling times in the harbour docks of Antwerp, the highest concentrations of TBT being found near a vessel repair facility. In one of the harbour docks, the concentrations of butyltins increased from May until August due to the discharge of tributyltin in hosing-down water and the launching of freshly painted sea-going vessels.

Interferences in ultratrace speciation of organolead and organotin by gas chromatography with atomic spectrometric detection

Interferences in trace and ultratrace speciation analysis of organotin and organolead compounds in various samples by gas chromatography coupled with atomic absorption spectrometry (AAS) and/or microwave induced plasma atomic emission spectrometry (MIP AES) are investigated. Particular attention is given to the effects of matrix co-extractives and reagents impurities introduced during sample preparation. Their influence on the detection limits is discussed in terms of baseline noise level, blank value, formation of artefacts and signal suppression. Loss of column resolution during the analysis of some matrices is observed.

Assessment of organolead species in the Austrian Danube-basin using GC-MIP-AED

Abstract In order to evaluate the effectiveness of recent restrictions of Austrian government for the consumption of leaded gasoline, ionic organolead species were determined in 13 sampling sites of the Austrian and Slovakian Danube-basin in 4 bimonthyl sampling campaigns. Speciation analysis was performed using a rapid and sensitive method based on Grignard derivatization of the ionic organolead species and a GC-MIP-AED coupling for separation and detection. The operational variables were optimized for chromatographic resolution and detection limits. 100 ml of sample were used for the analyses and the detection limits for trimethyllead were 0.5 ng Pb l–1 and for triethyllead 0.85 ng Pb l–1. In general, absence of organolead induced pollution has been observed for most of the sampling locations and campaigns. Only the part of the river Danube between Vienna (Austria) and Bratislava (Slovakia), which is loaded by various intensive anthropogenic sources, showed in two campaigns the occurrence of very low trimethyl- and triethyllead concentrations, ranging between 1.2–12.0 ng Pb l–1 and 1.6–5.8 ng Pb l–1, respectively.