Thesis (DSc (Chemistry and Polymer Science))--University of Stellenbosch, 2009. / Unstabilised polyolefins are susceptible to degradation when exposed to molecular oxygen, heat, irradiation as well as chemical and mechanical stimuli. Oxidation leads to changes in molecular properties such as molecular weight, molecular weight distribution, chemical composition, chemical composition distribution and crystallisability. Conventional analytical techniques are of limited use when studying the degradation of heterogeneous materials such as impact polypropylene copolymers (ICPP). These copolymers consist of a number of components of different monomer contents, isotacticity and crystallinity, ranging from amorphous EPR to highly crystalline polypropylene. The individual components are affected differently by degradation, leading to heterogeneity within the degradation of impact copolymers. Novel analytical approaches that acknowledge the heterogeneity in sample composition are needed to study the degradation behaviour of such heterogeneous materials. This study describes the combination of fractionation and hyphenated techniques with conventional analyses for extensive structural characterisation of complex impact copolymers as well as their degradation behaviour. Temperature rising elution fractionation (TREF) coupled to conventional techniques such as size exclusion chromatography (SEC), Fourier-Transform infrared spectroscopy (FTIR), Carbon-13 nuclear magnetic resonance (13C-NMR) and differential scanning calorimetry (DSC) indicated the ICPPs in question to consist of four main components, namely ethylene-propylene random copolymers (EPR), isotactic PP (iPP), as well as semi-crystalline ethylene-propylene copolymers (EPC) and lower isotacticity PP. The degradation of an ICPP was studied by a multi-component analysis procedure consisting of TREF coupled to SEC, 13C-NMR, as well as SEC-FTIR. Results obtained by this procedure indicated the change in crystallisability of the bulk sample observed by TREF, crystallisation analysis fractionation (CRYSTAF) and DSC to be the result of the preferential degradation of the iPP phase. Degradation of ICPPs initiates within this phase where chain scission and carbonyl group insertion leads to a change in the crystallisability of iPP chains. During TREF of degraded bulk ICPPs, the degraded iPP molecules elute at lower elution temperatures, depending on their degree of degradation. The other components of the copolymer were degraded to a lesser extent. Degradation products were also found to be heterogeneously distributed across the molecular weight distribution of each fraction, with a higher concentration appearing at the low molecular weight side. The multi-component analysis procedure was also used to study the difference in degradation behaviour between ICPPs of different comonomer content, isotacticity and crystallinity. The spatial heterogeneity of degradation within ICPPs was studied by Fourier-Transform infrared microspectroscopy (FTIR-μS). A heterogeneous distribution of degradation products was found across the depth of thicker sample specimens. These results were compared to those obtained by conventional layer-by-layer milling followed by SEC, FTIR and CRYSTAF. The principles of degradation within thick samples were similar to that observed for thin films, although additional contributions by sample morphology and oxygen diffusion were detected.

O trabalho buscou investigar as variações sazonais de metabólitos secundários em Eremanthus glomerulatus Less (Asteraceae). Embora não ser utilizada para fins medicinais esta espécie contem substâncias biologicamente ativas. Para este estudo, foram selecionados dez indivíduos de uma mesma população localizada na região do município de Ibiraci - MG, que durante um período de aproximadamente dois anos (06/2000 a 04/2002) tiveram um de seus ramos coletados mensalmente. Visando a análise das folhas destes ramos uma metodologia para extração e análise de seus metabólitos secundários majoritários por CLAE-UV foi desenvolvida e utilizada para determinação de suas variações sazonais. A identificação destes metabólitos se deu principalmente pelas técnicas hifenadas CLAE-DAD-EM e CLAE-DAD-EM/EM. Os metabólitos que não puderam ser identificados por estas ferramentas foram isolados do extrato etanólico foliar desta espécie e identificados por RMN de 1H e 13C e EM. Durante este estudo foi verificado que o envelhecimento das folhas resulta em uma significativa redução no conteúdo de todos os seus metabólitos secundários. Também foi possível identificar nove metabólitos secundários pertencentes as classes dos ácidos cafeoilquínicos, derivados fenólicos e flavonóides, dos quais foram isolados três, sendo dois ainda não relatados na literatura. Quanto a variação sazonal pode-se verificar que os indivíduos apresentam perfis metabólicos bem semelhante com diferenças quantitativas mas praticamente não apresentando variações qualitativas entre os indivíduos. Pode-se observar também que há um metabolismo bem diversificado no qual nem sempre todos os indivíduos apresentam aumento de produção de um mesmo metabólito em determinada estação do ano. Apesar das variáveis é possível definir o outono e a primavera como as estações que durante o estudo apresentaram os melhores índices de produção de praticamente todos os metabólitos analisados. Por fim pode-se concluir que as variações sazonais em E. glomerutalus são significativas e que são determinantes para definir a época de futuras coletas para posteriores estudos químicos ou farmacológicos. / This study was performed to investigate the seasonal intrapopulational variations of the secondary metabolites in Eremanthus glomerulatus Less (Asteraceae). Although this species is not used for medicinal purposes, it contains biologically active substances. For this study, ten individuals from the same population located in the region of Ibirici city, Minas Gerais state, had one of their lbranches collected monthly for about two years (from 06/2000 to 04/2002). Aiming the analysis of the leaves from the branches, a methodology on UV-HPLC was developed and used for the extraction and analysis of major secondary metabolites to determine the seasonal variations. The identification of the metabolites has occurred mainly by the HPLC-DAD-MS and HPLC-DAD-MS/MS hyphenated techniques. The metabolites that could not be identified by these methods were isolated from ethanolic extract of leaves of these species and identified by NMR 1H and 13C and MS. During this study it was noticed that the aging of the leaves results in a significant reduction on the rate of all the secondary metabolites. It was also possible to identify nine secondary metabolites belonging to caffeoylquinic acids, phenolical derivatives and flavonoids, from which, three compounds were isolated, however two compounds wasnt described in the literature. Relating to the seasonal variation, it was possible to verify that the individuals present similar metabolic profiles with quantitative differences but practically without qualitative difference. It was also possible to observe that there is a diversified metabolism in which not all individuals present an increase in the production of the same metabolite on a specific season. Despite these variations, it is possible to define autumn and spring as the seasons that presented the best rates of production on practically all the analyzed metabolites. Finally, it is possible to conclude that the seasonal variation of E. glomerutalus is significant and decisive to define the right time for future collection for further chemical and pharmacological studies.

O trabalho buscou investigar as variações sazonais de metabólitos secundários em Eremanthus glomerulatus Less (Asteraceae). Embora não ser utilizada para fins medicinais esta espécie contem substâncias biologicamente ativas. Para este estudo, foram selecionados dez indivíduos de uma mesma população localizada na região do município de Ibiraci - MG, que durante um período de aproximadamente dois anos (06/2000 a 04/2002) tiveram um de seus ramos coletados mensalmente. Visando a análise das folhas destes ramos uma metodologia para extração e análise de seus metabólitos secundários majoritários por CLAE-UV foi desenvolvida e utilizada para determinação de suas variações sazonais. A identificação destes metabólitos se deu principalmente pelas técnicas hifenadas CLAE-DAD-EM e CLAE-DAD-EM/EM. Os metabólitos que não puderam ser identificados por estas ferramentas foram isolados do extrato etanólico foliar desta espécie e identificados por RMN de 1H e 13C e EM. Durante este estudo foi verificado que o envelhecimento das folhas resulta em uma significativa redução no conteúdo de todos os seus metabólitos secundários. Também foi possível identificar nove metabólitos secundários pertencentes as classes dos ácidos cafeoilquínicos, derivados fenólicos e flavonóides, dos quais foram isolados três, sendo dois ainda não relatados na literatura. Quanto a variação sazonal pode-se verificar que os indivíduos apresentam perfis metabólicos bem semelhante com diferenças quantitativas mas praticamente não apresentando variações qualitativas entre os indivíduos. Pode-se observar também que há um metabolismo bem diversificado no qual nem sempre todos os indivíduos apresentam aumento de produção de um mesmo metabólito em determinada estação do ano. Apesar das variáveis é possível definir o outono e a primavera como as estações que durante o estudo apresentaram os melhores índices de produção de praticamente todos os metabólitos analisados. Por fim pode-se concluir que as variações sazonais em E. glomerutalus são significativas e que são determinantes para definir a época de futuras coletas para posteriores estudos químicos ou farmacológicos. / This study was performed to investigate the seasonal intrapopulational variations of the secondary metabolites in Eremanthus glomerulatus Less (Asteraceae). Although this species is not used for medicinal purposes, it contains biologically active substances. For this study, ten individuals from the same population located in the region of Ibirici city, Minas Gerais state, had one of their lbranches collected monthly for about two years (from 06/2000 to 04/2002). Aiming the analysis of the leaves from the branches, a methodology on UV-HPLC was developed and used for the extraction and analysis of major secondary metabolites to determine the seasonal variations. The identification of the metabolites has occurred mainly by the HPLC-DAD-MS and HPLC-DAD-MS/MS hyphenated techniques. The metabolites that could not be identified by these methods were isolated from ethanolic extract of leaves of these species and identified by NMR 1H and 13C and MS. During this study it was noticed that the aging of the leaves results in a significant reduction on the rate of all the secondary metabolites. It was also possible to identify nine secondary metabolites belonging to caffeoylquinic acids, phenolical derivatives and flavonoids, from which, three compounds were isolated, however two compounds wasnt described in the literature. Relating to the seasonal variation, it was possible to verify that the individuals present similar metabolic profiles with quantitative differences but practically without qualitative difference. It was also possible to observe that there is a diversified metabolism in which not all individuals present an increase in the production of the same metabolite on a specific season. Despite these variations, it is possible to define autumn and spring as the seasons that presented the best rates of production on practically all the analyzed metabolites. Finally, it is possible to conclude that the seasonal variation of E. glomerutalus is significant and decisive to define the right time for future collection for further chemical and pharmacological studies.

The following work describes the instrumentation and application of hyphenated FT-IR techniques specifically involving supercritical fluid extraction (SFE), supercritical fluid chromatography (SFC), and liquid chromatography (LC). Three studies are presented. The first involves the application of SFE/FT-IR towards the extraction of finishes from textile fibers. SFE has previously been applied to less complex finish systems. The proposed method making use of intermediate trapping is viable for more complex systems that show limited solubility in a supercritical fluid. Quantification of the percent finish on yarn was performed and results were favorable when compared with plant data. The range of applications was expanded to on-line SFE/SFC in the extraction and analysis of components from the polymer matrix itself. SFE/SFC/FT-IR was used to identify extractable components from a variety of Nylons. Following identification of one of the primary extractables, caprolactam, SFE/SFC was used to quantitate the amount of residual starting material in a Nylon copolymer. The second study involves the extractables in polystyrene which is a softer polymer with respect to solubility of components in supercritical CO ₂. Dimers and trimers as well as processing agents were identified via FT-IR with relatively mild supercritical extraction conditions. Following these two studies was the expansion of hyphenated FT -IR to mobile phase elimination. A system optimization was carried out using polymer additive standards. The effects of nebulizer flow, sheath flow, and sheath temperature were shown. The data were analyzed at in terms of library matches as well as GramSchmidt reconstruction peak heights. Peak intensities were the primary source for choosing optimum conditions. Under optimized conditions, approximately 200 ng of analyte were analyzed and found to be above the limit of detection. The applicability of the interface was demonstrated by the identification/analysis of triclosan, an antibacterial agent, in Colgate toothpaste. Aside from the identification of the analyte this study was used to show the effect of deposition parameters such as disk rotation rate as well as the effectiveness of FT-IR spectral library searches. The analysis of triglycerides was also carried out to show the effectiveness of using LC/FTIR for viscous liquids which are difficult analytes to deposit onto a solid substrate. Using this FT-IR technique allowed one to look at the degree of saturation/unsaturation in an olive oil sample. The linearity of the method was shown using a set of triglyceride standards. Lastly, the feasibility of using the commercially manufactured mobile phase elimination interface for SFC was demonstrated. Additive standard was deposited using both pure and methanol modified CO₂. No effluent split mechanism was used for decompressed flows up to 150 mL/min. Detection limits are proposed to fall in the low (10 - 25) ng range. The infrared spectra are enhanced over those acquired with a flow cell interface because CO₂ absorbance bands no longer obscure a portion of the analyte absorption spectrum. / Ph. D.

No description available.

Uma das principais características da família Asteraceae é sua capacidade de produzir uma grande diversidade de metabólitos secundários que podem possuir efeitos terapêuticos ou tóxicos. Para verificar a existência de variações inter e intrapopulacionais na sua composição metabólica secundária de Lychnophora granmongolense (Duarte) Semir & Leitão Filho e caracterização desses metabólitos foi desenvolvida uma metodologia analítica em CLAE DAD. Essa metodologia permitiu a identificação de três compostos, vicenina-2, quercetina e pinocembrina, através da coinjeção de padrões, ou seja, pela comparação do tempo de retenção com padrões previamente isolados associados com os dados do espectro no UV. Com a utilização da técnica de espectrometria de massas, CLAE-DAD-EM e CLAE-DAD-EM/EM, foram identificadas quatro lactonas sesquiterpênicas (LST), centraterina, 4,5-di-idrocentraterina, lychnofolido e 15-desoxigoyazensolido. No estudo de variação populacional, os resultados indicaram grandes variações quantitativas e qualitativas tanto inter quanto intrapopulacionais para os metabólitos de alta e média polaridade. A análise dos metabólitos mais apolares presentes nas folhas permitiu a identificação de 8 triterpenos e 8 triterpenos acetilados. Contudo, esses metabólitos apresentam somente pequena variação que não é significativa. Assim, esse estudo contribuiu para o aumento do conhecimento sobre o ritmo metabólico dessa espécie. / One of the main characteristics of plants of the Asteraceae family is their capacity to produce a huge diversity of secondary metabolites having therapeutic and toxic effects. An analytical method was developed based on HPLCDAD which was used to verify the existence of variations in Lychnophora granmongolense (Duarte) Semir & Leitão Filho secondary metabolite levels among species within populations and between distinct populations and to characterize the major secondary metabolites. Through this method three compounds, namely vicenin-2, quercetin and pinocembrin were identified by co-injection of standards. This identification was based on the comparison of retention time with isolated standards and the UV spectrum. Four sesquiterpenes lactones centratherin, 4,5-dihydrocentratherin, lycnopholide and 15-deoxygoyazensolide were identified by mass spectrometry techniques coupled with HPLC (HPLC-DAD-MS e HPLC-DAD-MS/MS). In the populational variation study, the results show large qualitative and quantitative differences among species within populations and between populations for high and medium polarity secondary metabolites. Eight triterpenes and eight acetyl triterpenes were identified by apolar compound analysis. However, small, insignificant variation was observed for these particular metabolites. Thus, this study contributed to an increase in the knowledge of the metabolic rhythm of this specie.

A análise pelas técnicas hifenadas CLAE-DAD-EM e CLAE-DAD-EM/EM de extratos foliares de Lychnophora ericoides Mart. levou à identificação de 34 metabólitos secundários diretamente a partir dos extratos vegetais. Destes, 19 foram relatados pela primeira vez na subtribo Lychnophorinae. Uma metodologia para extração e análise destes metabólitos por CLAE-DAD foi desenvolvida, validada e utilizada para determinação de suas variações populacionais e temporais. Perfis metabólicos bem semelhantes, com diferenças quantitativas, mas não qualitativas, foram observados entre os indivíduos de uma mesma população. Entre as cinco populações analisadas, foi observado um metabolismo secundário bem mais diversificado, caracterizado pela presença de lactonas sesquiterpênicas, nas plantas da população de Ibiraci-MG. As concentrações mais elevadas de ácidos cafeoilquínicos foram encontradas no período da seca no cerrado (inverno) e as menores quando a planta se encontrava florida. Os teores de flavonóides foram maiores durante o período de chuvas (verão) e os de C-glicosilflavonas e lactonas sesquiterpênicas se mantiveram estáveis. Variações circadianas significativas de flavonóides e ácidos cafeoilquínicos também foram observadas nas duas populações nas quais estes fatores foram estudados. Foi verificado que o envelhecimento das folhas resulta em uma pronunciada redução no conteúdo de todos os metabólitos secundários e concentrações menores dos metabólitos foram observadas nas folhas dos ramos floridos em relação aos ramos sem flores de um mesmo indivíduo. Finalmente, conclui-se que as variações temporais e populacionais observadas em L. ericoides podem ser determinantes para a intensidade da atividade antiinflamatória e/ou analgésica desta planta, utilizada popularmente para estes propósitos. / The analyses of Lychnophora ericoides Mart. leaves extracts by HPLC-DAD-MS and HPLC-DAD-MS/MS resulted in the identification of 34 secondary metabolites directly from the plant extracts. Nineteen of these metabolites are being reported for the first time in the Lychnophorinae subtribe. A method for the extraction and analyses of these metabolites by CLAE-DAD was developed, validated and employed for the determination of their populational and temporal variations. Very similar metabolic profiles, exhibiting quantitative but not qualitative differences, were found among each population individuals. Among the five studied populations, a more diversified secondary metabolism, characterized by sesquiterpene lactones presence, was observed for the plants collected at Ibiraci-MG. The highest concentrations of caffeoylquinic acids were found in the cerrado dry season (winter), and the lowest when the plants were blooming. The flavoinoid contents were higher during the rainy season (summer), while C-glucosylflavones and sesquiterpene lactones levels remained stable. Significant circadian variations were also detected regarding flavonoids and caffeoylquinic acids in the two populations analyzed on this respect. It was also found a pronounced reduction in the contents of all the secondary metabolites as the leaves get old. Lower levels of all the metabolites were also found for the flowery branches when compared to the non flowery ones in the same individual. Finally, it can be concluded that the temporal and populational variations detected in L. ericoides leaves could highly influence the intensity of the anti-inflammatory and/or analgesic activities of this plant, used in popular medicines for these purposes.

Uma das principais características da família Asteraceae é sua capacidade de produzir uma grande diversidade de metabólitos secundários que podem possuir efeitos terapêuticos ou tóxicos. Para verificar a existência de variações inter e intrapopulacionais na sua composição metabólica secundária de Lychnophora granmongolense (Duarte) Semir & Leitão Filho e caracterização desses metabólitos foi desenvolvida uma metodologia analítica em CLAE DAD. Essa metodologia permitiu a identificação de três compostos, vicenina-2, quercetina e pinocembrina, através da coinjeção de padrões, ou seja, pela comparação do tempo de retenção com padrões previamente isolados associados com os dados do espectro no UV. Com a utilização da técnica de espectrometria de massas, CLAE-DAD-EM e CLAE-DAD-EM/EM, foram identificadas quatro lactonas sesquiterpênicas (LST), centraterina, 4,5-di-idrocentraterina, lychnofolido e 15-desoxigoyazensolido. No estudo de variação populacional, os resultados indicaram grandes variações quantitativas e qualitativas tanto inter quanto intrapopulacionais para os metabólitos de alta e média polaridade. A análise dos metabólitos mais apolares presentes nas folhas permitiu a identificação de 8 triterpenos e 8 triterpenos acetilados. Contudo, esses metabólitos apresentam somente pequena variação que não é significativa. Assim, esse estudo contribuiu para o aumento do conhecimento sobre o ritmo metabólico dessa espécie. / One of the main characteristics of plants of the Asteraceae family is their capacity to produce a huge diversity of secondary metabolites having therapeutic and toxic effects. An analytical method was developed based on HPLCDAD which was used to verify the existence of variations in Lychnophora granmongolense (Duarte) Semir & Leitão Filho secondary metabolite levels among species within populations and between distinct populations and to characterize the major secondary metabolites. Through this method three compounds, namely vicenin-2, quercetin and pinocembrin were identified by co-injection of standards. This identification was based on the comparison of retention time with isolated standards and the UV spectrum. Four sesquiterpenes lactones centratherin, 4,5-dihydrocentratherin, lycnopholide and 15-deoxygoyazensolide were identified by mass spectrometry techniques coupled with HPLC (HPLC-DAD-MS e HPLC-DAD-MS/MS). In the populational variation study, the results show large qualitative and quantitative differences among species within populations and between populations for high and medium polarity secondary metabolites. Eight triterpenes and eight acetyl triterpenes were identified by apolar compound analysis. However, small, insignificant variation was observed for these particular metabolites. Thus, this study contributed to an increase in the knowledge of the metabolic rhythm of this specie.

<p>This thesis is based on studies in which the suitability of various gas chromatography (GC) injection techniques was examined for the determination of polybrominated diphenyl ethers (PBDEs) and carbazoles, two groups of compounds that are thermally labile and/or have high boiling-points. For such substances, it is essential to introduce the samples into the GC system in an appropriate way to avoid degradation and other potential problems. In addition, different types of gas chromatographic column system and mass spectrometric detectors were evaluated for the determination of PBDEs.</p><p>Conventional injectors, such as splitless, on-column and programmed temperature vaporizing (PTV) injectors were evaluated and optimized for determination of PBDEs. The results show on-column injection to be the best option, providing low discrimination and high precision. The splitless injector is commonly used for “dirty” samples. However, it is not suitable for determination of the high molecular weight congeners, since it tends to discriminate against them and promote their degradation, leading to poor precision and accuracy. The PTV injector appears to be a more suitable alternative. The use of liners reduces problems associated with potential interferents such as polar compounds and lipids and compared to the hot splitless injector, it provides gentler solvent evaporation, due to its temperature programming feature, leading to low discrimination and variance.</p><p>Increasing the injection volume from the conventional 1-3 µL to >50 µL offers two main benefits. Firstly, the overall detection and quantification limits are decreased, since the entire sample extract can be injected into the GC system. Secondly, large volume injections enable hyphenation of preceding techniques such as liquid chromatography (LC), solid phase extraction and other kinds of extraction. Large-volume injections were utilized and optimized in the studies included in this thesis.</p><p>With a loop-type injector/interface large sample volumes can be injected on-column providing low risk of discrimination against compounds with low volatility. This injector was used for the determination of PBDEs in air and as an interface for the determination of carbazoles by LC-GC. Peak distortion is a frequently encountered problem associated with this type of injector that was addressed and solved during the work underlying this thesis.</p><p>The PTV can be used as a large volume injector, in so-called solvent vent mode. This technique was evaluated for the determination of PBDEs and as an interface for coupling dynamic sonication-assisted solvent extraction online to GC. The results show that careful optimization of the injection parameters is required, but also that the PTV is robust and yields reproducible results.</p><p>PBDEs are commonly detected using mass spectrometry in electron capture negative ionization (ECNI) mode, monitoring bromine ions (m/z 79 and 81). The mass spectrometric properties of the fully brominated diphenyl ether, BDE-209, have been investigated. A high molecular weight fragment at m/z 486/488 enables the use of 13C-labeled BDE-209 as an internal surrogate standard.</p>

This thesis is based on studies in which the suitability of various gas chromatography (GC) injection techniques was examined for the determination of polybrominated diphenyl ethers (PBDEs) and carbazoles, two groups of compounds that are thermally labile and/or have high boiling-points. For such substances, it is essential to introduce the samples into the GC system in an appropriate way to avoid degradation and other potential problems. In addition, different types of gas chromatographic column system and mass spectrometric detectors were evaluated for the determination of PBDEs. Conventional injectors, such as splitless, on-column and programmed temperature vaporizing (PTV) injectors were evaluated and optimized for determination of PBDEs. The results show on-column injection to be the best option, providing low discrimination and high precision. The splitless injector is commonly used for “dirty” samples. However, it is not suitable for determination of the high molecular weight congeners, since it tends to discriminate against them and promote their degradation, leading to poor precision and accuracy. The PTV injector appears to be a more suitable alternative. The use of liners reduces problems associated with potential interferents such as polar compounds and lipids and compared to the hot splitless injector, it provides gentler solvent evaporation, due to its temperature programming feature, leading to low discrimination and variance. Increasing the injection volume from the conventional 1-3 µL to &gt;50 µL offers two main benefits. Firstly, the overall detection and quantification limits are decreased, since the entire sample extract can be injected into the GC system. Secondly, large volume injections enable hyphenation of preceding techniques such as liquid chromatography (LC), solid phase extraction and other kinds of extraction. Large-volume injections were utilized and optimized in the studies included in this thesis. With a loop-type injector/interface large sample volumes can be injected on-column providing low risk of discrimination against compounds with low volatility. This injector was used for the determination of PBDEs in air and as an interface for the determination of carbazoles by LC-GC. Peak distortion is a frequently encountered problem associated with this type of injector that was addressed and solved during the work underlying this thesis. The PTV can be used as a large volume injector, in so-called solvent vent mode. This technique was evaluated for the determination of PBDEs and as an interface for coupling dynamic sonication-assisted solvent extraction online to GC. The results show that careful optimization of the injection parameters is required, but also that the PTV is robust and yields reproducible results. PBDEs are commonly detected using mass spectrometry in electron capture negative ionization (ECNI) mode, monitoring bromine ions (m/z 79 and 81). The mass spectrometric properties of the fully brominated diphenyl ether, BDE-209, have been investigated. A high molecular weight fragment at m/z 486/488 enables the use of 13C-labeled BDE-209 as an internal surrogate standard.