Analysis Of Trace Amounts Of Toxaphene By Comprehensive Two-dimensional Gas Chromatography

Toxaphene is a broad spectrum chlorinated insecticide that is a complex mixture of thousandsof congeners. Because of its persistence, bioaccumulation, and inherent toxicity, toxaphene is nowregarded as an organic chlorinated pollutant of worldwide concern，and is one of12persistentorganic pollutants in the Stockholm Convention. The analysis of toxaphene is still a majorchallenge because of its complexity, and because each congener has a different response factor.Toxaphene chromatograms acquired by using one-dimensional gas chromatography (ID GC) showthat this technique cannot be used to separate all of the toxaphene congeners. In this thesis work, anew method of which comprehensive two-dimensional gas chromatography was coupled withmicro-electron capture detector/mass spectrum for the anal’ysis of industrial toxaphene/indicatortoxaphene congeners was established. Comprehensive studies were carried out on the analyticalmethod of toxaphene in environmental matrix. This method was succesfully applied to analyzetoxaphene in environmental samples. The major results are summarized below.1.It is a challenge to extract target analytes that are present at very low concentrations andseparate them from complex matrices. The sample preparation (i.e., extraction and cleanup)techniques were evaluated and optimized. Soxhlet extraction(SE) and accelerated solventextraction(ASE) were applied on soil samples in order to evaluate their extraction effiency. ForToxaphene, the ASE extraction generally yielded higher results compared with the SE extraction,with the normalized recovery ranges of91%?102%, Using multi-acid silica gel column andactivation silica gel column is the best purified method. The results indicated that the recovery ofinternal standard were65%?115%, and reproducibility of the method were blow30%。2.A new method was developed for the group analysis of toxaphene mixtures using acomprehensive two-dimensional gas chromatography coupled with micro electron-capture detector(GCxGC-jiECD). Columns with different polarity and selectivity, including DB-XLB，DB-1MSand HP-IMS, were used as first dimension and combined with columns of increasing polarity inthe second dimension，i.e. BPX50and BPX70. An DB-1MS (30m x0.25mm x0.25(+.im) BPX50(2m x0.1mm x0.1|.im) revealed a complex mixture of over900compounds which is asignificantly higher number than that in any study before. And GCxGC-fiECD parametersincluding temperature programs, carrier gas flow rate and modulation period etc. were alsooptimized. Toxaphene congeners were well separated with the optimized methods. The peak areasof all congeners of difYerent chlorinated toxaphene were calculated. It is found that hepta-, octa- and nona-chlorinatcd compounds were the major components and contirbute85%of the totaltoxaphcne mass. The matrix-matched external standard calibration curves were used forquantitative analysis. Linear range of this method were10?500|ig/L and limit of detection were0.3-0.6|ig/L of the different chloirnated toxaphene. The repeatability and reproducibility at aconcentration of lOpg/L evaluated as the RSDs calculatcd, was less than20%(n=7). It can be seenthe use of comprehensive two-dimensional GC substantially improves the quality of toxapheneanalysis compared to otic-dimensional gas chromatography (1D-GC)’ hundreds congeners could beseparated in toxaphene atfer a run which took less than2h. These results illustrate the potential ofthe GC X GC—jiECD developed for the fast analysis of trace amount of complex compounds.3. We developed and validated a sensitive and quantitative method for determining threeindicator toxaphene congcners in soil using an isotope dilution/comprehensive two-dimensional gaschromathy-tandem mass spectrometry (GOGC-MS). l3ograpCio’labeled Parlar26and50wereused as intenral standards and ’^Cio-labeled Parlar62was used as an injection standard. The sampleextraction and purification treatments and the GOGC-MS parameters were optimized.Subsequently the samples were determined by GCXGC-MS. The limits of detection for Parlar26，50, and62were0.6pg/g,0.4pg/g, and1.0pg/g (S/N=3), respectively, and the calibration curveshad good linear correlations between50and1000fig/L (2r>0.99). This analytical method meetsthe requirements for trace analysis of toxaphene congeners. Comprehensive two-dimensional GCgave substantial improvements over one-dimensional GC in the toxaphene analysis. We analyzedsoil samples containing trace quantities of toxaphene to demonstrate that the developed methodcould be used to analyze toxaphene in environmental samples.