Electron Capture Negative Ionization Research Articles

Regulation of Folate-mediated One-carbon Metabolism by 10-Formyltetrahydrofolate Dehydrogenase

10-Formyltetrahydrofolate dehydrogenase (FDH) catalyzes the NADP(+)-dependent conversion of 10-formyltetrahydrofolate to CO(2) and tetrahydrofolate (THF) and is an abundant high affinity folate-binding protein. Although several activities have been ascribed to FDH, its metabolic role in folate-mediated one-carbon metabolism is not well understood. FDH has been proposed to: 1) inhibit purine biosynthesis by depleting 10-formyl-THF pools, 2) maintain cellular folate concentrations by sequestering THF, 3) deplete the supply of folate-activated one-carbon units, and 4) stimulate the generation of THF-activated one-carbon unit synthesis by channeling folate cofactors to other folate-dependent enzymes. The metabolic functions of FDH were investigated in neuroblastoma, which do not contain detectable levels of FDH. Both low and high FDH expression reduced total cellular folate concentrations by 60%, elevated rates of folate catabolism, and depleted cellular 5-methyl-THF and S-adenosylmethionine levels. Low FDH expression increased the formyl-THF/THF ratio nearly 10-fold, whereas THF accounted for nearly 50% of total folate in neuroblastoma with high FDH expression. FDH expression did not affect the enrichment of exogenous formate into methionine, serine, or purines and did not suppress de novo purine nucleotide biosynthesis. We conclude that low FDH expression facilitates the incorporation of one-carbon units into the one-carbon pool, whereas high levels of FDH expression deplete the folate-activated one-carbon pool by catalyzing the conversion of 10-formyl-THF to THF. Furthermore, FDH does not increase cellular folate concentrations by sequestering THF in neuroblastoma nor does it inhibit or regulate de novo purine biosynthesis. FDH expression does deplete cellular 5-methyl-THF and S-adenosylmethionine levels indicating that FDH impairs the folate-dependent homocysteine remethylation cycle.

Gas chromatography and mass spectrometry of methoxylated polybrominated diphenyl ethers (MeO‐PBDEs)

Twenty-six methoxylated polybrominated diphenyl ethers (MeO-PBDEs) were characterized by gas chromatography (GC) on four different GC columns with different lengths and polarities, as well as by mass spectrometry using three ionization techniques, electron ionization (EI), electron capture negative ionization (ECNI) and positive ion chemical ionization (PICI). MeO-PBDE congeners with similar retention times on a nonpolar GC column were separated when analyzed on a polar GC column. EI can be used to determine the position of the methoxy substituent (ortho, meta or para) relative to the diphenyl ether oxygen in the MeO-PBDEs. The PICI ionization technique is shown to be valuable to generate structural information of the MeO-PBDEs, i.e. the degree of bromination on both the methoxy-substituted ring and the entirely brominated phenyl ring can be obtained. This structure information can also be achieved for certain MeO-PBDEs with the methoxy group in ortho position to the diphenyl ether bond in ECNI mode. Like other brominated compounds ECNI is preferable when analyzing environmental samples for quantification of MeO-PBDEs because of the formation of bromide ions, which enables low detection limits.

Quantitative analysis of polychlorinated n-alkanes in environmental samples

Polychlorinated n-alkanes (PCAs) are persistent organic pollutants of concern due to their toxicological properties, their capability to bioaccumulate and their widespread, unrestricted use. PCAs are classified according to the length of the alkane chain as short-chain chlorinated paraffins (SCCPs), medium-chain CPs (MCCPs) and long-chain CPs (LCCPs). PCAs represent a difficult analytical problem because of the complexity inherent in industrial mixtures. The total number of possible congeners is unknown, but far exceeds 10,000. Many procedures for separation and quantification of these contaminants have been described. However, most relevant works refer to SCCPs, and some others also include MCCPs. But, methodologies for LCCPs are very rare. In this article, we discuss different aspects of current analytical methodology, such as sample preparation, extraction, purification and final determination. Most PCA analyses have been performed by gas chromatography (GC) coupled to electron capture negative ionization (ECNI) mass spectrometry (MS), although alternatives based on the use of electron ionization tandem MS (EI-MS) 2 and metastable atom bombardment (MAB) have been reported. New methodologies based on the use of comprehensive two-dimensional GC have also been developed. We discuss the advantages and the disadvantages of the different instrumental techniques, and outline conclusions and perspectives for the future.

Congener group patterns of chloroparaffins in marine sediments obtained by chloride attachment chemical ionization and electron capture negative ionization

Congener group patterns of technical short chain and medium chain chloroparaffins (SCCP and MCCP) were determined by electron capture negative ionization (ECNI) and chloride attachment chemical ionization (CACI) mass spectrometry (MS). In contrast to CACI–MS, congener patterns obtained by ECNI showed always a shift to the next higher chlorinated congener and carbon chain length group. Consequently, the calculated molecular masses and chlorine contents were higher for ECNI (factor 1.10 ± 0.03 and 1.09 ± 0.03, respectively). ECNI/CACI ratios in sediment samples from the North and Baltic Sea were also slightly higher. However, a more pronounced shift of the congener pattern for a given carbon chain length to congeners with 2–3 more chlorine atoms was observed. SCCP and MCCP concentrations obtained by ECNI–MS were in the range of 8–63 ng g −1 (North Sea) and 22–149 ng g −1 dry weight (Baltic Sea). MCCP levels were highest in all samples (MCCP/SCCP factor 1.1–3.2).

Determination of the enantiomer fraction of PBB 149 by gas chromatography/electron capture negative ionization tandem mass spectrometry in the selected reaction monitoring mode

Enantioselective determination of the atropisomers of 2,2',3,4',5',6-hexabromobiphenyl (PBB 149) in a purified sample from a bird egg was attempted in this work. By application of the classic method for PBB determination, i.e. gas chromatography coupled to electron capture negative ionization mass spectrometry (GC/ECNI-MS) using the bromide ions, the enantiomers interfered with another brominated compound. Subsequent measurements clarified that this interference did not occur in the mass chromatogram of the molecular ion of PBB 149. Therefore, a GC/ECNI tandem mass spectrometry (MS/MS) method was developed, based on the fragmentation of [M]-. A suitable precursor-product ion transition was found for m/z 627.5 --> 80 +/- 1.5, representing the most abundant ion trace of the molecular ion and the bromide ions. Optimization of the ion source temperature, the methane gas pressure, and the collision voltages resulted in a robust method that could solve the problem. Subsequent injections of a technical PBB product (Firemaster BP-6) resulted in the anticipated racemic proportion (enantiomer fraction (EF) = 0.50 +/- 0.02 (n = 8)). By contrast, the EF in the purified extract of a bird egg was found to be 0.42 +/- 0.02 (n = 10), indicative of a significant enantioenrichment of the second eluting atropisomer. Additional measurements were performed on a non-chiral column. These measurements allowed for the detection of 16 hexabromobiphenyls (hexa-BBs) in Firemaster BP-6. These comparisons verified that PBB 149 enantiomers did not interfere with an isomer that could falsify the enantiomer fraction in the sample. The novel method using GC/ECNI-MS/MS in the selected reaction monitoring (SRM) mode was eight times more sensitive than application of conventional GC/ECNI-MS selected ion monitoring (SIM) analysis of the molecular ion.

Identification of Brominated Carbazoles in Sediment Cores from Lake Michigan

During the analysis of brominated flame retardants in sediment cores taken from Lake Michigan, a group of unknown brominated compounds were observed. To identify their chemical structures, a variety of gas chromatographic mass spectrometric techniques were used. With the help of high-resolution and positive chemical ionization mass spectrometry, the molecular formula of the most abundant congener was established to be C12H5Br4N. On the basis of the electron impact and electron capture negative ionization mass spectra, this chemical was suspected of being a tetrabromocarbazole. The structure was confirmed by comparing the mass spectra and gas chromatographic retention times of an authentic standard of 1,3,6,8-tetrabromocarbazole with those of the most abundant unknown. The other unknown compounds may be other bromocarbazole congeners. The time trend determined by measuring these compounds as a function of depth in the Lake Michigan sediment cores indicated that the concentration of 1,3,6,8-tetrabromocarbazole peaked around 1920-1935. This is the first time that bromocarbazoles have been found in the environment.

Identification, Quantification, and Synthesis of a Novel Dimethoxylated Polybrominated Biphenyl in Marine Mammals Caught Off the Coast of Japan

Bioaccumulation of persistent organic compounds can eventually lead to concentrations in wildlife and humans that are deleterious to health. The present paper documents the identification, quantification, and synthesis of a novel compound, 2,2'-dimethoxy-3,3',5,5'-tetrabromobiphenyl (2,2'-diMeO-BB80), present in the marine mammals Striped dolphin (Stenella coeruleoalba), Bottlenose dolphin (Tursiops truncatus), Minke whale (Balaenoptera acutorostrata), and Baird's beaked whale (Berardius bairdii) caught in the Pacific Ocean. Identification was based on comparison of the relative retention times of the compound on two gas chromatographic columns of different polarities to those of an authentic standard. Furthermore, this identification was also supported by comparison of the full scan mass spectrometric data collected employing electron ionization (El), positive ion chemical ionization (PICI), and electron capture negative ionization (ECNI). The concentrations of 2,2'-diMeO-BB80 in the samples ranged from 12 to 800 ng/g lipid, making this consistently one of the most abundant compounds among those analyzed, including polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCDD), and methoxylated PBDEs. The known occurrence of 3,3',5,5'-tetrabromo-2,2'-biphenyldiol (2,2'-diOH-BB80) in the marine environment as a natural product suggests that its methylated derivative, 2,2'-diMeO-BB80, is also of natural origin. To obtain the necessary authentic standards, synthesis was performed of 2,2'-diMeO-BB80 and the known natural product 2',6-dimethoxy-2,3',4,5'-tetrabromodiphenyl ether (2',6-diMeO-BDE68).

Optimization of the determination of polybrominated diphenyl ethers in human serum using solid-phase extraction and gas chromatography-electron capture negative ionization mass spectrometry

A simple, rapid, sensitive and reproducible method based on solid-phase extraction (SPE) and acidified silica clean-up was developed for the measurement of 12 polybrominated diphenyl ethers (PBDEs), including BDE 209, and 2,2',4,4',5,5'-hexabromobiphenyl (BB 153) in human serum. Several solid-phase sorbents (Empore C(18), Isolute Phenyl, Isolute ENV+ and OASIS HLB) were tested and it was found that OASIStrade mark HLB (500 mg) gives the highest absolute recoveries (between 64% and 95%, R.S.D.<17%, n=3) for all tested analytes and internal standards. Removal of co-extracted biogenic materials was performed using a 6 ml disposable cartridge containing (from bottom to top) silica impregnated with sulphuric acid, activated silica and anhydrous sodium sulphate. PBDEs and BB 153 were quantified using a gas chromatograph coupled with a mass spectrometer (MS) operated in electron-capture negative ionization mode. The method limits of quantification (LOQ) ranged between 0.2 and 25 pg/ml serum (0.1 and 4 ng/g lipid weight). LOQs were dependent on the analyte levels in procedural blanks which resulted in the highest LOQs for PBDE congeners found in higher concentrations in blanks (e.g. BDE 47, 99 and 209). The use of OASIS HLB SPE cartridge allowed a good method repeatability (within- and between-day precision<12% for all congeners, except for BDE 209<17%, n=3). The method was applied to serum samples from a random Belgian population. The obtained results were within the range of PBDE levels in other non-exposed population from Europe.

Identification of Polybrominated Dibenzo-p-dioxins in Blue Mussels (Mytilus edulis) from the Baltic Sea

Polybrominated dibenzo-p-dioxins (PBDDs) are known to be formed as byproducts in connection with the manufacture and combustion of products containing brominated flame retardants. However, to date little is known about the occurrence of PBDDs in biological samples. The aim of the present investigation was to examine the presence of PBDDs in blue mussels (Mytilus edulis) from the Baltic Sea employing a procedure adapted for dioxin analysis. Two triBDDs (1,3,7-triBDD and 1,3,8-triBDD) were identified in biota here for the first time. This identification was based on accurate mass determination and comparison of retention times on three gas chromatographic columns of different polarities (PTE 5, SP-2331, and OV1701/heptakis) with synthesized standards, together with comparisons of electron capture negative ionization (ECNI) and electron ionization (EI) mass spectra. In addition, five PBDDs and one polybrominated dibenzofuran (PBDF) were tentatively identified; altogether, one diBDD, three triBDDs, three tetraBDDs, and one triBDFwere detected in the blue mussels. To our knowledge this is the first time PBDDs have been identified in biota of the Baltic Sea. The sigma triBDD concentration in the blue mussels was estimated to be 170 ng/g lipids. The origin of these PBDDs remains unclear, but a plausible hypothesis could be biogenic formation in the marine environment.

Enantioselective Determination of Chiral Toxaphene Congeners in Laying Hens and Eggs Using Multidimensional High-Resolution Gas Chromatography

A total of 22 chiral toxaphene congeners were analyzed in organ tissues and eggs of laying hens after they had been fed with food spiked with technical toxaphene. For the analysis, multidimensional high-resolution gas chromatography using a chiral column coated with randomly silylated heptakis(O-tert-butyldimethylsilyl)-beta-cyclodextrin, electron capture detection, and valveless "live column switching" technique was applied. The analytical results were additionally confirmed with mass spectral data, recorded in electron-capture negative ionization mode with selected-ion monitoring mass spectrometry. During both the feeding period of the laying hens with toxaphene-contaminated food (38 weeks, accumulation phase) and the following subsiding period without toxaphenes (another 14 weeks, decontamination phase), organs (liver, kidney, skin/fat), blood, meat, and eggs of the hens served as model matrices for toxaphene uptake. The enantiomeric ratios (ERs) of congeners 26, 31, 32, 40, 41, 42(a+b), 44, 50, and 62--known as the most important components of technical toxaphene occurring in the environment--could be analytically determined. Significant differences were observed with respect to their initial racemic ratios. On the basis of their chemical structures, the metabolic pathways of some congeners could be explained. Astonishingly, some of the toxaphenes applied as racemates could merely be found as single enantiomers at the end of the feeding program, for example, congener 32 in blood and meat samples or congener 44, especially in organ tissues, which showed ERs of zero or infinity. The findings of this study impressively emphasize that it is essential to isolate and analyze individual toxaphene enantiomers in food and biota tissues to be capable of evaluating their toxicity and metabolization more specifically.

Trace Analysis of Semivolatile Organic Compounds in Large Volume Samples of Snow, Lake Water, and Groundwater

An analytical method was developed for the trace analysis of a wide range of semivolatile organic compounds (SOCs) in 50-L high-elevation snow and lake water samples. The method was validated for 75 SOCs from seven different chemical classes (polycyclic aromatic hydrocarbons, organochlorine pesticides, amides, triazines, polychlorinated biphenyls, thiocarbamates, and phosphorothioates) that covered a wide range of physical-chemical properties including 7 orders of magnitude of octanol-water partition coefficient (log K(ow) = 1.4-8.3). The SOCs were extracted using a hydrophobically and hydrophilically modified divinylbenzene solid-phase extraction device (modified Speedisk). The average analyte recovery from 50 L of reverse osmosis water, using the modified Speedisk, was 99% with an average relative standard deviation of 4.8%. Snow samples were collected from the field, melted, and extracted using the modified Speedisk and a poly(tetrafluoroethylene) remote sample adapter in the laboratory. Lake water was sampled, filtered, and extracted in situ using an Infiltrex 100 fitted with a 1-microm glass fiber filter to trap particulate matter and the modified Speedisk to trap dissolved SOCs. The extracts were analyzed by gas chromatographic mass spectrometry with electron impact ionization and electron capture negative ionization using isotope dilution and selective ion monitoring. Estimated method detection limits for snow and lake water ranged from 0.2 to 125 pg/L and 0.5-400 pg/L, respectively. U.S. historic and current-use pesticides were identified and quantified in snow and lake water samples collected from Rocky Mountain National Park, CO. The application of the analytical method to the analysis of SOCs in large-volume groundwater samples is also shown.

New quantification procedure for the analysis of chlorinated paraffins using electron capture negative ionization mass spectrometry

An improved quantification procedure for the analysis of chlorinated paraffins (CPs) is presented based on electron capture negative ionization mass spectrometry. It compensates differences in response factors between reference CP mixtures and the CP pattern present in environmental samples. The use of a CP standard with a matching degree of chlorination is no longer necessary. It could be shown that the response factors of C 10-, C 11-, C 12- and C 13-CP mixtures of both 50 and 60% chlorine content were only slightly influenced by the carbon chain length. A linear correlation ( R 2 = 0.965) between the total response factor of a CP mixture and its chlorine content was obtained for seven short chain chlorinated paraffin mixtures (SCCP, C 10–C 13) with different composition and chlorine content (51–69%). Maximum single deviations were <7% for this reference set. It allowed to determine the correct total response factor of the CP composition present in a sample. The deviations were not more than 7–33% for five independent SCCP control samples compared to up to 373% for the conventional procedure. The procedure was tested by quantifying the SCCP and MCCP levels in 10 fish liver samples. The proposed method allowed to compensate the influence of the degree of chlorination of the applied reference standard on the total response factor.

Analysis of 7‐methylguanine using isotope dilution and gas chromatography/electron‐capture negative chemical ionization mass spectrometry

This paper presents results obtained for in vivo endogenous and exogenous 7-methylguanine (7-MG) analyzed using a method incorporating gas chromatography with electron-capture negative chemical ionization mass spectrometry and isotope dilution (GC/EC-ID-MS). 13C4-Labeled 7-MG was synthesized to serve as an internal standard to improve accuracy of quantitation, and was used to analyze 7-MG in livers of control mice and dacarbazine-treated mice. The results confirm that 7-MG in tissue DNA can be measured using this GC/EC-ID-MS method with excellent sensitivity and specificity. Administration of 0, 30, and 60 mg/kg dacarbazine to mice led to dose-dependent increases in the formation of 7-MG. The results indicate that this method could be applied to the analysis of endogenous and exogenous 7-MG in human tissues for future molecular epidemiology studies on potential health effects caused by methylating agents.

Characterization of polychlorinated n-alkanes using comprehensive two-dimensional gas chromatography–electron-capture negative ionisation time-of-flight mass spectrometry

Comprehensive two-dimensional gas chromatography with electron-capture negative ionization time-of-flight mass spectrometry (GC × GC–ECNI-TOF-MS) is used to study the composition and characteristics of short-, medium- and long-chain polychlorinated n-alkane (PCA) mixtures. Distinct ordered structures, which enable the highlighting and interpretation of group and sub-group separations are observed when using a DB-1 × 007-65HT column combination. The analysis of a number of, mutually rather different, technical mixtures and 35 individual standard compounds provides information on the role of chlorine substitution (number of substituents as well as their position), the contribution of carbon versus chlorine atoms to analyte volatility, i.e. GC × GC behaviour, and the influence of the chain length of the carbon skeleton. Two dust samples are analyzed to illustrate the practical usefulness of the proposed procedure.

Hydroxylated and Methoxylated Brominated Diphenyl Ethers in the Red Algae Ceramium tenuicorne and Blue Mussels from the Baltic Sea

Methoxylated polybrominated diphenyl ethers (MeO-PBDEs) and hydroxylated PBDEs (OH-PBDEs) have recently been identified in fish and wildlife from the Baltic Sea. Both OH-PBDEs and MeO-PBDEs are known natural products, while OH-PBDEs also may be metabolites of PBDEs. The aim of the present study was to determine if the red macroalga Ceramium tenuicorne could be a source for MeO- and OH-PBDEs in the Baltic environment. Blue mussels (Mytilus edulis) from the same area were also investigated for their content of MeO- and OH-PBDEs. Seven OH-PBDEs and four MeO-PBDEs were present both in the red macroalga and the blue mussels. The mussels also contained a monochlorinated OH-tetraBDE. One of the compounds, 6-methoxy-2,2',3,4,4',5-hexabromodiphenyl ether, has never been reported to occur in the environment. The identification was based on comparison of relative retention times with reference standards, on two gas chromatographic columns of different polarities, together with comparisons of full-scan electron capture negative ionization (ECNI) and electron ionization (EI) mass spectra. It is shown that MeO-PBDEs and OH-PBDEs are present in algae, but at this stage it could not be confirmed if the compounds are produced by the alga itself or by its associated microflora and/or microfauna.

Comparison of Highly-Fluorinated Chloroformates as Direct Aqueous Sample Derivatizing Agents for Hydrophilic Analytes and Drinking-Water Disinfection By-Products

Four highly-fluorinated alkyl and aryl chloroformates, including 2,2,3,3,4,4,5,5-octafluoro-1-pentyl chloroformate (OFPCF), 2,3,4,5,6-pentafluorobenzyl chloroformate (PFBCF), 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-1-octyl chloroformate (TDFOCF), and 2-(2,3,4,5,6-pentafluorophenoxy)-ethyl chloroformate (PFPECF), were synthesized and tested as reagents for the direct water derivatization of polar and hydrophilic analytes. The goal of this research was to develop an optimal derivatizing agent to aid in the identification of highly polar ozonation drinking water disinfection by-products (DBPs) that are believed to be missed with current analytical procedures. The chemical properties (reactivity, selectivity, derivatization products, and their chromatographic and spectral features) for the four chloroformates were investigated using a set of highly polar standard analytes, including malic and tartaric acids, hydroxylamine, valine, 2-aminoethanol, resorcinol, 1,3,5-trihydroxybenzene, and 2,4-dihydroxybenzoic acid. Upon derivatization, the analytes were extracted from the aqueous solvent and analyzed by gas chromatography (GC)-mass spectrometry (MS) in the electron capture negative ionization (ECNI) mode. Positive chemical ionization (PCI)-MS was used for confirmation of molecular ions that were weak or absent in ECNI mass spectra. Of the four derivatizing reagents tested, OFPCF showed the best performance, with good reaction efficiency, good chromatographic and spectroscopic properties, low detection limits (10-100 fmol), and a linear response more than two orders of magnitude. Further, the entire procedure from raw aqueous sample to ready-to-inject hexane solutions of the derivatives requires less than 10 min. PFBCF showed ideal applicability for derivatizing aminoalcohols and aminoacids. The two chloroformates with the highest intrinsic stability (TDFOCF and PFPECF) failed to derivatize some of the analytes. Finally, the OFPCF derivatizing agent was tested with simulated ozonated drinking water (aqueous fulvic acid treated with ozone), and three highly polar reaction by-products were determined.

Quantitative Analysis of 39 Polybrominated Diphenyl Ethers by Isotope Dilution GC/Low-Resolution MS

A GC/low-resolution MS method for the quantitative isotope dilution analysis of 39 mono- to heptabrominated diphenyl ethers was developed. The effects of two different ionization sources, electron impact (EI) and electron capture negative ionization (ECNI), and the effects of their parameters on production of high-mass fragment ions [M - xH - yBr](-) specific to PBDEs were investigated. Electron energy, emission current, source temperature, ECNI system pressure, and choice of ECNI reagent gases were optimized. Previously unidentified enhancement of PBDE high-mass fragment ion [M - xH - yBr](-) abundance was achieved. Electron energy had the largest impact on PBDE high-mass fragment ion abundance for both the ECNI and EI sources. By monitoring high-mass fragment ions of PBDEs under optimized ECNI source conditions, quantitative isotope dilution analysis of 39 PBDEs was conducted using nine (13)C(12) labeled PBDEs on a low-resolution MS with low picogram to femtogram instrument detection limits.

Risk Assessment of Short-Chain Chlorinated Paraffins in Japan Based on the First Market Basket Study and Species Sensitivity Distributions

The chemical risks of short-chain chlorinated paraffins (SCCPs) to human health and ecological species in Japan were assessed in this study. SCCPs are used as extreme pressure additives in metal-working fluids and flame retardant agents in plastic materials. The first market basket study with a high resolution gas chromatography and mass spectrometry with electron capture negative ionization is reported. Total daily food intakes for Japanese residents of different ages were estimated using Latin Hypercube simulations, and the highest 95th percentile intake is 6.8 x 10(2) ng/kg/day for a 1-year-old child. Based on the reported no-observed-adverse-effect-level (NOAEL) and the estimated exposure mainly from food, it was concluded thatSCCPs are not posing risks to humans in Japan. Ecological risks to aquatic and sediment organisms were estimated using species sensitivity distributions. The 95th percentiles of the distributions obtained by fitting several environmental SCCP concentration data of river water and sediment were 41.8 ng/L and 558 ng/g wet weight as the possible highest concentrations, respectively. No-observed-effect-concentrations (NOEC) were determined by calculating the fifth percentiles of a species sensitivity distribution, which were 2.2 microg/L for aquatic organisms and 1.7 to 13.5 mg/ kg wet weight for sediment organisms. While it is likely that there is no imminent environmental chemical risk for aquatic organisms at a regional level in Japan, this study concluded that a more detailed risk assessment is necessary for sediment organisms.

Multivariate cluster analysis as a versatile tool for the quality assessment of short chain chloroparaffin quantification in environmental samples

The compositions of commercially available solutions of short chain chlorinated paraffins (SCCP) and technical mixtures were determined by high resolution gas chromatography (HRGC) electron capture negative ionisation (ECNI) combined with low resolution mass spectrometry (LRMS). Differences and similarities in the relative distribution of congeners and homologues were investigated by cluster analysis. Samples could be separated into two groups/clusters with similar molecular mass, chlorination degree and congener pattern. With the exception of one sample, the use of CH4-ECNI-MS led to an overestimation of the chlorine content. Moreover, the influence of different SCCP mixtures on the quantification was studied. The results showed that small differences in the chlorine content could sometimes cause substantial systematic errors of up to 119% despite similar homologue and congener patterns. Errors of quantification corresponded to the deviations between response factors of sample and standard. As a consequence SCCPs should be quantified with a standard matching the overall response factor of the sample.

Nitro musk metabolites bound to carp hemoglobin: determination by GC with two MS detection modes: EIMS versus electron capture negative ion MS

Nitroaromatic compounds including synthetic nitro musks are important raw materials and intermediates in the synthesis of explosives, dyes, pesticides, and pharmaceutical and personal-care products (PPCPs). The nitro musks such as musk xylene (MX) and musk ketone (MK) are extensively used as fragrance ingredients in PPCPs and other commercial toiletries. Identification and quantification of a bound 4-amino-MX (4-AMX) metabolite as well as a 2-amino-MK (2-AMK) metabolite were carried out by gas chromatography–mass spectrometry (GCMS), with selected ion monitoring (SIM) in both the electron ionization (EIMS) and electron capture (EC) negative ion chemical ionization (NICIMS) modes. Detection of 4-AMX and 2-AMK occurred after the cysteine adducts in carp hemoglobin, derived from the nitroso metabolites, were released by alkaline hydrolysis. The released metabolites were extracted into n-hexane. The extract was preconcentrated by evaporation, and analyzed by GC-SIM-MS. A comparison between the EI and EC approaches was made. EC NICIMS detected both metabolites whereas only 4-AMX was detected by EIMS. The EC NICIMS approach exhibited fewer matrix responses and provided a lower detection limit. Quantitation in both approaches was based on an internal standard and a calibration plot.