摘要:

AbstractDeterminations of tributyltin (TBT) species, along with the degradation products mono‐ and dibutyltin (MBT and DBT), are routinely carried out by a number of laboratories to ascertain the level of organotin contamination of the marine enviroment, particularly in water, sediment and biota. In order to improve and control the quality of such analyses the EC Community Bureau of Reference, BCR (Measurements and Testing Programme), has organized two interlaboratory studies on TBT in water and TBT in a spiked sediment which were followed by a certification campaign for butyltins in a coastal sediment (CRM 462). This material was collected in the Arcachon Bay (France), then carefully prepared (controlled oven drying) and its homogeneity and long‐term stability were verified. This paper presents the certification work performed. The certified values for TBT and DBT are 70±14 ng g−1(as TBT cation) and 128±16 ng g−1(as DBT cation), res

ISSN:0268-2605    

DOI:10.1002/aoc.590080713

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractFollowing two interlaboratory studies on tributyltin species (TBT) in water and TBT‐spiked sediment, the EC Community Bureau of Reference (BCR) (Measurements and Testing Programme) organized in 1992 an interlaboratory study on TBT in a harbour sediment (RM 424) to investigate sources of error possibly occurring in the analysis of a complicated matrix and to attempt to certify this material. The sediment was collected in the Sado Estuary (P), then carefully prepared, and its homogeneity and stability were verified. The low TBT content encountered in this material, and the high level of interferences, created difficulties with the techniques using hydride generation, whereas better agreement was obtained for other derivatization techniques with GC/FPD and GC/MS. This paper presents the results of the interlaboratory study. The reference value for TBT in this material is 20±5 ng g−1(as TBT cation) and the indicative values for dibutyltin (DBT) and monobutyltin (MBT) are 53±19 ng g−1(as DBT cation) and 257±54 ng g−1(as MBT cation), respectively. Owing to the difficulties encountered, the reference material was not certified and is considered as a research material to be used for the evaluation of the performance of analytical techniques for the determination of low TBT levels in a diffic

ISSN:0268-2605    

DOI:10.1002/aoc.590080714

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractExisting methods for analysis of methylmercury in biota consist of an initial extraction of the determinand at low pH with an organic solvent, followed by clean‐up and gas chromatographic determination. The complex biological matrix causes considerable interferences in the extraction process and makes the calibration of the method a difficult task. Results from the calibration method (standard addition) will only be correct if the calibrant added and the determinand are in the same chemical form and homogeneously distributed in the sample to be analysed. It is shown here that this presupposition is fulfilled if the sample is pretreated with an aqueous solution of sodium hydroxide (alkaline hydrolysis). In order to avoid uncontrolled losses of methylmercury at high pH, cysteine is added at the beginning of the pretreatment procedure. As a reagent forming strong complexes with mercury compounds, it protects methylmercury from disintegration during alkaline hydrolysis of the sampl

ISSN:0268-2605    

DOI:10.1002/aoc.590080715

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractTributyltin (TBT) concentrations have been measured in UK waters, shellfish and sediments during the period 1986–1992. The methodology was based on conversion of alkyltin compounds to hydrides following extraction, and then measurement by gas chromatography with flame photometric detection. The collection of a large set of data to assess changes in environmental concentrations of organotins required use of good analytical quality control procedures at a time when no reference materials were available. An analytical quality control (AQC) system based on in‐house quality control materials was devised and the performance of the method independently assessed by periodic participation in intercalibration exercises with other expert laborator

ISSN:0268-2605    

DOI:10.1002/aoc.590080716

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe analytical method using ethylation, gas chromatography–cold vapor atomic fluorescence spectroscopy (GC–CV AFS), combined with different pretreatment procedures, has been used for the determination of methylmercury (MeHg) in various aqueous and solid environmental samples. Different types of samples with varying matrices and MeHg concentration levels require different pretreatment procedures in order to isolate/separate MeHg from the sample matrix, and to overcome interferences in the ethylation reaction process. Limitations of different pretreatment procedures (solvent extraction into methylene chloride, distillation under nitrogen flow and alkaline digestion) are discussed and recommendations are given. The influence of the quality of the ethylating reagent on the analytical results is also exami

ISSN:0268-2605    

DOI:10.1002/aoc.590080717

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractA study of the total mercury and methylmercury distribution in esturine sediments is presented. Core sediments obtained in a polluted area were freeze‐dried and sieved to obtain four fractions. Fraction 1, having grain size<0.30 mm; Fraction 2, having grain size<0.30 mm; Fraction 3, with grain size1 mm. In all these fractions total mercury (Cold Vapor AAS) and methylmercury (Gas Chromatography with ECD detection) have been analyzed. As expected high concentrations of total mercury and small concentrations of methylmercury were obtained in Fractions 1 and 2 but were not detected in Fractions 3 and 4, although the study of the data obtained suggests that significant amounts of geochemical mercury remain in these fractions. Attempts have been made to correlate data for both species when freeze dried sediments and the raw wet samples were analyze

ISSN:0268-2605    

DOI:10.1002/aoc.590080718

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractIn the application of GC ECD procedures for methylmercury analysis and organomercury speciation, frequent column‐treatments must be carried out to maintain the analytical system under statistical control. Often the decision to carry out a new treatment is taken without any statistical assistance. Several quality control techniques have been applied to decide the best time to make these treatments. A Trigg tracking signal chart in combination with a moving estimate of standard deviation charts gives the best indication about the timing of each new treatmen

ISSN:0268-2605    

DOI:10.1002/aoc.590080719

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractA method of detecting methylmercury species (MeHg) and dimethylmercury (DMM) has been studied. MeHg was transformed prior to its determination as methylmercury hydride (MMH) by use of NaBH4. The two volatile forms of organic mercury were detected by a purge and trap (PT) unit in‐line with a gas chromatograph (GC) connected with a Fourier transform infrared spectrometer (FTIR) which was also in‐line with an atomic absorption spectrometer (AAS). Environmental samples were analyzed by this technique. MeHg was detected in thiosulfate extracts of fish and sediment, and MeHg and DMM directly in water samples. Picogram levels of sensitivity were obtained, the limit of detection being 100 pg for MeHg and 50 pg for DMM. The calibration graph was linear for both compounds up to 10 ng as

ISSN:0268-2605    

DOI:10.1002/aoc.590080720

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractPentylated derivatives of six environmentally important organotin compounds were obtained by using a Grignard derivatization. The purity of these pentylated calibrants was checked by gas chromatography–quartz furnace atomic absorption spectrometry (GC QFAA) and gas chromatography–mass spectrometry ion‐trap detection (GC MS‐ITD). Through combination of the total tin contents of every pentylated organotin standard, obtained after wet acid destruction of 0.5 ml of the respective calibrant, and the species composition or impurities present in the same standard, a well‐defined pentylated organotin standard was obtained which could be used to calibrate GC QFAA and GC atomic emission detection (AED) systems.In a similar way aqueous organotin standards can be obtained, which can be used in spiking experiments to verify the recovery efficiency of a developed analytical extraction procedure for o

ISSN:0268-2605    

DOI:10.1002/aoc.590080721

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractAn interlaboratory programme has been started within the Measurements and Testing Programme (formerly BCR) of the European Commission to evaluate the performance of analytical techniques used for the determination of trimethyl‐lead in simulated rainwater and urban dust. A first interlaboratory study on solutions was successfully concluded in 1993 and a second exercise was organized, focusing on simulated rainwater and urban dust analysis. This paper reports the results of this second interlaboratory study, which is a preparatory step for a certification campaign of simulated rainwater (with representative contamination levels) and urban dus

ISSN:0268-2605    

DOI:10.1002/aoc.590080722

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY