Identification of dimethylarsinoyl-riboside derivatives in seaweed by pneumatically assisted electrospray tandem mass spectrometry

Pneumatically-assisted electrospray tandem mass spectrometry (ES MS/MS) was proposed as a technique for the identification of dimethylarsinoyl-riboside derivatives (arsenosugars) in seaweed (Laminaria). Conditions for the acquisition of MS and MS/MS spectra were optimized. A size-exclusion HPLC (SE HPLC) step was developed for the purification of algal extracts prior to ES MS. The arsenosugar fraction was found to elute prior to the majority of other arsenic compounds. The identity of the compounds expected to be arsenosugar compounds was confirmed by the collision induced dissociation (CID) of the relevant protonated molecule ions. An independent confirmation of the identity of analytes was obtained by two-dimensional (size-exclusion–anion exchange) HPLC–ICP MS with signal identification by spiking with the appropriate arsenosugar standards.     

In vitro biotransformation of an arsenosugar by mouse anaerobic cecal microflora and cecal tissue as examined using IC-ICP-MS and LC-ESI-MS/MS

This investigation examined chemical and microbiological transformations of an arsenosugar by mouse cecum. To mimic the low oxygen environment in the mammalian gastrointestinal tract, reaction mixtures were incubated under anaerobic conditions. An arsenosugar extracted from ribbon kelp, 3-[5'-deoxy-5-(dimethylarsinoyl)-beta-ribofuranosyloxy]-2-hydroxypropanesulfonic acid, As392, was added to reaction mixtures that contained either cecal microflora or cecal tissue homogenate. These reaction mixtures were incubated at 0 or 37 degrees C for up to 48 hours to monitor biotransformation of the arsenosugar. Analysis of the reaction mixtures by IC-ICP-MS and LC-ESI-MS/MS indicated that the arsenosugar was converted primarily (95%) to its sulfur analog in less than 1 h at 37 degrees C. Conversion of As392 to its sulfur analog was much slower at 0 degrees C (21% conversion after 48 h). In reaction mixtures with cecal tissue homogenate, conversion of As392 to its sulfur analog was slower (77% conversion after 48 h at 37 degrees C). A good mass balance was found in all reaction mixtures between the amount of arsenosugar added and the sum of all detected arsenic-containing products. LC-ESI-MS/MS spectra of the sulfur-containing arsenosugar formed in all reaction mixtures containing cecal microflora compared well with those of a synthetic standard. These results suggest that the anaerobic microflora of the gastrointestinal tract can rapidly convert ingested arsenosugars to sulfur analogs. This biotransformation may affect the subsequent absorption, metabolism, and disposition of arsenic present in arsenosugars.     

A systematic study on the extractability of arsenic species from algal certified reference material IAEA-140/TM (Fucus sp., Sea Plant Homogenate) using methanol/water extractant mixtures

Using methanol/water mixtures (from pure water to pure methanol), with different desorption and solubility parameters, and varying extractant volume to algal mass (V/m) ratios, the extractability of arsenic species from CRM IAEA-140/TM was investigated. A linear sorption isotherm-based model was developed to process the data obtained with variable volume extraction, allowing the unambiguous deduction of the maximal extractable species concentrations under the specific extraction conditions, even for more stable species.The maximal extractable arsenic fraction ranged from 41 to 68% of the total arsenic concentration in CRM IAEA-140/TM, depending on the extractant composition, with pure methanol giving the lowest extraction yield and pure water giving erratic extractability (probably due to bad wettability). The main arsenic species quantified in the methanol/water extracts were arsenosugars, with arsenosugars 1 (glycerol arsenosugar), 3 (sulfonate arsenosugar) and 4 (sulfate arsenosugar) making up ca. 90% of the maximal extractable arsenic. The rest accounts for DMA (dimethylarsinate), arsenosugar 2 (phosphate arsenosugar) and As(V). There is no clear extraction pattern emerging from the data although it may be seen that extraction of more polar species (e.g. arsenosugar 1) is favoured in pure methanol and less polar more ionic species (e.g. arsenosugar 2 and As(V)) in methanol extractants with a higher water percentage.The precise and highly accurate data may be used for quality control purposes under strictly followed extraction conditions since the extraction is operationally defined. Additionally, the variable volume extraction methodology presented may be applied to other elemental species in other matrices using other extractants. Although this approach does not maximise the absolute extractability but only that which is extractant-specific, experimentators are forewarned that in most cases only a fingerprint of the extractant-specific species is produced unless a quantitative extraction of all species is obtained.     

Determination of arsenic species in oyster tissue by microwave‐assisted extraction and liquid chromatography–atomic fluorescence detection

A method for the determination of arsenic species in oyster tissue is established. The extraction of arsenic species is carried out by using low‐power microwaves. Quantitative extraction is obtained at a power of 40 W, and in 5 min, using the extracting agent methanol/water (1 + 1). The measurements are carried out using liquid chromatography–UV irradiation–hydride generation–atomic fluorescence detection (LC–UV–HG–AFS). Three arsenic species were detected in oyster tissue: arsenobetaine (AsBet) (87%), a probable arsenosugar (AsS) (4.9%), and dimethylarsinate (DMA) (4.7%). No influence of the clean‐up, the microwave field or the IR drying system on the stability of the arsenic compounds was observed. The extracts can be kept stable up to 3 days at 4 °C. The performance of the method is proved on fresh samples, as they are usually analysed in routine laboratories. Copyright © 2001 John Wiley & Sons, Ltd.     

Quantification of urinary N-acetyl-S- (propionamide)cysteine using an on-line clean-up system coupled with liquid chromatography/tandem mass spectrometry

Acrylamide has been reported to be present in high-temperature processed foods and normal processed food intake could lead to significant acrylamide exposure. Acrylamide in vivo can be conjugated with glutathione in the presence of glutathione transferase. This conjugation product is further metabolized and excreted as N-acetyl-S-(propionamide)cysteine (NASPC) in the urine. NASPC could be considered a biomarker for acrylamide exposure. The objective of this study was to develop a highly specific, rapid and sensitive method to quantify urinary NASPC, serving as a biomarker for acrylamide exposure assessment. Isotope-labeled [13C3]NASPC was successfully synthesized and used as an internal standard. This urine mixture was directly analyzed using a newly developed liquid chromatographic/tandem mass spectrometric method coupled with an on-line clean-up system. The detection limit for this method was estimated as < 5 microg l(-1)(0.4 pmol) on-column. The method was applied to measure the urinary level of NASPC in 70 apparently health subjects. The results showed that the NASPC urinary level was highly associated with smoking. Smokers had a significantly higher urinary NASPC level (135 +/- 88 microg g(-1) creatinine) than non-smokers (76 +/- 30 microg g(-1) creatinine). A highly sensitive and selective LC/MS/MS isotope dilution method was successfully established. With an on-line clean-up system, this system is capable of routine high-throughput analysis and accurate quantitation of NASPC in urine. This could be a useful tool for health surveillance for acrylamide exposure in a population for future study.     

Liquid chromatography with electrospray ion-trap mass spectrometry for the determination of anatoxins in cyanobacteria and drinking water

Anatoxin-a (AN) and homoanatoxin-a (HMAN) are potent neurotoxins produced by a number of cyanobacterial species. A new, sensitive liquid chromatography/multiple tandem mass spectrometry (LC/MS(n)) method has been developed for the determination of these neurotoxins. The LC system was coupled, via an electrospray ionisation (ESI) source, to an ion-trap mass spectrometer in positive ion mode. The [M+H](+) ions at m/z 166 (anatoxin-a) and m/z 180 (homoanatoxin-a) were used as the precursor ions for multiple MS experiments. MS(2)bond;MS(4) spectra displayed major fragment ions at m/z 149 (AN), 163 (HMAN), assigned to [Mbond;NH(3)+H](+); m/z 131 (AN), 145 (HMAN), assigned to [Mbond;NH(3)bond;H(2)O+H](+), and m/z 91 [C(7)H(7)](+). Although the chromatographic separation of these neurotoxins is problematic, reversed-phase LC, using a C(18) Luna column, proved successful. Calibration data for anatoxin-a using spiked water samples (10 mL) in LC/MS(n) modes were: LC/MS (25-1000 microg/L), r(2) = 0.998; LC/MS(2) (5-1000(microg/L), r(2) = 0.9993; LC/MS(3) (2.5-1000 microg/L), r(2) = 0.9997. Reproducibility data (% RSD, N = 3) for each LC/MS(n) mode ranged between 2.0 at 500 microg/L and 7.0 at 10 microg/L. The detection limit (S/N = 3) for AN was better than 0.03 ng (on-column) for LC/MS(3) which corresponded to 0.6 microg/L.     

Determination of peanut allergens in cereal-chocolate-based snacks: metal-tag inductively coupled plasma mass spectrometry immunoassay versus liquid chromatography/electrospray ionization tandem mass spectrometry

A comparison of two methods for the identification and determination of peanut allergens based on europium (Eu)-tagged inductively coupled plasma mass spectrometry (ICP-MS) immunoassay and on liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) with a triple quadrupole mass analyzer was carried out on a complex food matrix like a chocolate rice crispy-based snack. The LC/MS/MS method was based on the determination of four different peptide biomarkers selective for the Ara h2 and Ara h3/4 peanut proteins. The performance of this method was compared with that of a non-competitive sandwich enzyme-linked immunosorbent assay (ELISA) method with ICP-MS detection of the metal used to tag the antibody for the quantitative peanut protein analysis in food. The limit of detection (LOD) and quantitation of the ICP-MS immunoassay were 2.2 and 5 microg peanuts g(-1) matrix, respectively, the recovery ranged from 86 +/- 18% to 110 +/- 4% and linearity was proved in the 5-50 microg g(-1) range. The LC/MS/MS method allowed us to obtain LODs of 1 and 5 microg protein g(-1) matrix for Ara h3/4 and Ara h2, respectively, thus obtaining significantly higher values with respect to the ELISA ICP-MS method, taking into account the different expression for concentrations. Linearity was established in the 10-200 microg g(-1) range of peanut proteins in the food matrix investigated and good precision (RSD <10%) was demonstrated. Both the two approaches, used for screening or confirmative purposes, showed the power of mass spectrometry when used as a very selective detector in difficult matrices even if some limitations still exist, i.e. matrix suppression in the LC/ESI-MS/MS procedure and the change of the Ag/Ab binding with matrix in the ICP-MS method.     

Arsenosugar identification in seaweed extracts using high-performance liquid chromatography/electrospray ion trap mass spectrometry

The development of analytical techniques suitable for providing structural information on a wide range of elemental species is a growing necessity. For arsenic speciation a variety of mass spectrometric techniques, mainly inductively coupled plasma mass spectrometry (ICP-MS) and electrospray tandem mass spectrometry (ES-MS/MS) coupled on-line with high-performance liquid chromatography (HPLC), are in use. In this paper we report the identification of arsenic species present in samples of marine origin (seaweed extracts) using ES ion trap mass spectrometry (IT) multistage mass spectrometry (MS(n)). Both reversed-phase and anion-exchange HPLC have been coupled on-line to ES-ITMS. Product ion scans with multiple stages of tandem MS (MS(n); n=2-4) were used to acquire diagnostic data for each arsenosugar. The spectra contain structurally characteristic fragment ions for each of the arsenosugars examined. In addition it was observed that upon successive stages of collision-induced dissociation (CID) a common product ion (m/z 237) was formed from all four arsenosugars examined. This product ion has the potential to be used as an indicator for the presence of dimethylated arsenosugars (dimethylarsinoylribosides). The HPLC/ES-ITMS(n) method developed allows the sensitive identification of arsenosugars present in crude seaweed extracts without the need for extended sample preparation. In fact, sample preparation requirements are identical to those typically employed for HPLC/ICP-MS analysis. Additionally, the resulting product ions are structurally diagnostic of the arsenosugars examined, and tandem mass spectra are reproducible and correspond well to those obtained using other low-energy CID techniques. As a result, the HPLC/ES-ITMS(n) approach minimises the potential for arsenic species misidentification and has great potential as a means of overcoming the need for characterised standards.     

Optimization of HPLC-ICP-AES for the determination of arsenic species

High performance liquid chromatography coupled to ICP-AES detection provides a rapid, reliable and sensitive method for arsenic speciation. The separation of As(III), As(V), DMA and MMA was achieved with ion exchange chromatography coupled to an axially-viewed sequential ICP-AES. After optimization of the chromatographic parameters (pH and concentration of the mobile phase), a careful study of the interface was conducted. Five nebulizers associated to three spray chambers were tested. Response of the ICP to each arsenic species was strongly affected by the selection of the nebulizer and spray chamber, however similar responses were obtained for each arsenic species. Best signal-to-noise ratios were obtained by using a microconcentric nebulizer and a cyclone spray chamber and did not affect the chromatographic resolution. Detection limits better than 10 microg L(-1) were obtained for As(III), DMA, MMA and 20 microg L(-1) for As(V), which is a significant improvement over previously published results.     

Determination of amphetamine in rat brain by in vivo microdialysis and ion-pairing liquid chromatography with electrospray tandem mass spectrometry

An ion-pairing liquid chromatography/electrospray tandem mass spectrometry (LC/ES-MS/MS) method with in vivo microdialysis for the determination of amphetamine in rat brain has been developed. A microdialysis probe was surgically implanted into the striatum of the rat and artificial cerebrospinal fluid (aCSF) was used as the perfusion medium. Samples were collected and then analyzed off-line by LC/ES-MS/MS. A reversed-phase C18 column was employed for LC separation and MS/MS was utilized for detection. Trifluoroacetic acid (TFA) was added to the mobile phase (acetonitrile/water) as an ion-pairing reagent. Detection was by ES-MS/MS directly, and no post-column addition of organic modifier was needed. Dual linear ranges were determined from 0.1-0.5 microg/mL and 0.005-0.1 microg/mL, respectively. The detection limit, based on a signal-to-noise ratio of 3, was 0.001 microg/mL (5 nM). Good precision and accuracy were obtained. The applicability of this newly developed method was demonstrated by continuous monitoring of amphetamine concentrations in rat brain. Amphetamine reached a maximum concentration of 0.086 +/- 0.017 microg/mL over 20-40 min after a single 3.0 mg/kg intraperitoneal administration.     

Determination of total arsenic in serum and packed cellsof patients with renal insufficiency

In order to investigate the arsenic level in serum and packed cells of patients with renal insufficiency, total arsenic (As) concentrations were determined with hydride generation atomic absorption spectrometry (HGAAS) in serum (S) and packed cells (PC) of 31 non-dialyzed patients. The accuracy of the method was tested by the analysis of arsenic in 3 certified reference materials. Patients showed a three-fold increase of arsenic concentrations in serum and a two-fold increase of arsenic in packed cells compared with controls. Patients (n=10) with higher serum creatinine (>2.0 mg/dL), urea (>0.70 g/L) and urinary protein (mean+/-SD: 1.12+/-0.82 g/L) showed higher arsenic concentrations (5.8+/-3.3 microg/L in serum and 18.0+/-16.7 microg/kg in packed cells) compared with those with lower creatinine (<1.6 mg/dL), urea (<0.6 g/L) and urinary protein (mean+/-SD: 0.27+/-0.82 g/L) (n=16, serum arsenic 1.2+/-1.2 microg/L, packed cells arsenic 2.6+/-1.9 microg/kg). The significant differences (both p < 0.001) in S and PC-arsenic levels of patients in group I and II implies a relationship between the arsenic level and the degree of chronic renal insufficiency.     

Analysis of polar hydrophilic aromatic sulfonates in waste water treatment plants by CE/MS and LC/MS

The present work describes the development and optimization of a capillary (zone) electrophoresis/mass spectrometric (CE/MS) analysis method for polar hydrophilic aromatic sulfonates (ASs). The compounds were detected by negative ion electrospray ionization (NIESI) and selected ion monitoring (SIM). In comparison with CE/UV, for CE/MS a lower-concentration volatile ammonium acetate buffer (5 mM) without organic modifier and a higher separation voltage were better suited for separation. Sensitivity of CE/MS was slightly better than for CF/UV, with the limit of detection (LOD) ranging between 0.1 and 0.4 mg l(-1). For verification of the CE/MS results, ASs were also analysed by ion-pair liquid chromatography/diode array UV detection coupled in series with electrospray mass spectrometry (IPC/DAD/ESI-MS). Real water samples of different waste water treatment plants (WWTPs) in Catalonia (NE Spain) were extracted by solid-phase extraction (SPE) with LiChrolut EN and analysed with CE/MS and LC/MS. ASs were found in influent and effluent water samples of the WWTPs in the microg l(-1) concentration range. LC/MS offered a higher separation efficiency and sensitivity than CE/MS. Therefore with LC/MS more compounds could be identified in the WWTPs. The persistency of the ASs was distinct: some compounds were well degraded during the water treatment process, while others were quite persistent.     

Multielemental determination of arsenic, selenium and chromium(VI) species in water by high-performance liquid chromatography-inductively coupled plasma mass spectrometry

A new method for the simultaneous chromatographic separation and determination of arsenite, arsenate, mono-methylarsonic acid, dimethylarsinic acid, selenite, selenate and hexavalent chromium in water is presented. Speciation was achieved by on-line coupling of anion-exchange LC and inductively coupled plasma mass spectrometry (ICP-MS). Optimisation of the chromatographic conditions led to baseline separation of the seven species in 14 min using gradient elution with NH4NO3 20 mM, pH 8.7-NH4NO3 60 mM, pH 8.7 as mobile phase. Detection limits are in the range 40-60 ng l(-1) for arsenic species, around 130 ng l(-1) for Cr(VI), and higher for Se(IV) and Se(VI) (1.2 and 1.4 microg l(-1) respectively). The method showed good accuracy and repeatability, and no interference of chloride on 75As, 77Se or 53Cr was observed. The developed method was applied to the analysis of several environmental surface water samples.     

Antioxidant activity and cytotoxicity study of the flavonol glycosides from Bauhinia galpinii

The antioxidant activity of the crude extract and solvent fractions obtained from the leaves of Bauhinia galpinii was evaluated in terms of capacity to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals. The crude extract and the more polar solvent fractions (ethyl acetate and butanol) showed considerable antioxidant activity. The antioxidant potential of the extracts, expressed as EC50, ranged between 28.85 +/- 1.28 microg mL(-1)and 118.16 +/- 6.41 microg mL(-1). L-Ascorbic acid was used as a standard (EC50 = 19.79 +/- 0.14 microM). Bioassay guided fractionation of the two active solvent fractions led to the isolation of three flavonoid glycosides, identified as: quercetin-3-O-galactopyranoside (1), myricetin-3-O-galactopyranoside (2), and 2'-O-rhamnosylvitexin (3). These compounds are reported for the first time from this species. The structures of the compounds were determined on the basis of spectral studies (1H NMR, 13C NMR and MS). Their antioxidant potential was evaluated using a DPPH spectrophotometric assay. Compound 2 had higher and 3 had lower antioxidant activity than L-ascorbic acid. No cytotoxic effects were displayed by compounds 1 and 3, but compound 2 was cytotoxic to Vero cells (LC50 = 74.68 microg mL(-1)) and bovine dermis cells (LC50 = 30.69 microg mL(-1)).     

Determination of halofuginone and amprolium in chicken muscle and egg by liquid chromatography

A liquid chromatographic (LC) method was developed for simultaneous measurement of halofuginone (HFN) and amprolium (APL) in chicken muscle and egg. HFN and APL were extracted from chicken muscle and egg with acetonitrile. In chicken egg, they were partially purified by solid-phase extraction (SPE) to separate them from impurities. The LC separation was performed on a 4.6 mm id x 250 mm TSK-gel ODS-80TM column using acetonitrile-McIlvaine buffer, pH 3.4, containing 0.01M sodium lauryl sulfate (42 + 58) as the mobile phase. Ultraviolet detection of HFN and APL was performed at wavelengths of 242 and 265 nm, respectively. Recoveries of HFN and APL from chicken muscle spiked at 0.5 microg/g were 74.8 +/- 17.7 and 94.2 +/- 5.0%, respectively (mean +/- standard deviation [SD], n = 10). In chicken muscle, the lower limit of determination for both APL and HFN was 0.03 microg/g. Recoveries of HFN and APL from chicken egg spiked at 0.5 microg/g by a cleanup procedure using SPE were 54.6 +/- 3.4 and 85.0 +/- 2.4%, respectively (mean +/- SD, n = 5). In chicken egg, the lower limit of determination for both APL and HFN was 0.04 microg/g.     

Gas chromatography/negative ion chemical ionization mass spectrometry and liquid chromatography/electrospray ionization tandem mass spectrometry quantitative profiling of N-acetylcysteine conjugates of valproic acid in urine: application in drug metabolism studies in humans

We report a GC/NICI-MS assay and a LC/ESI-MS/MS assay for the analysis of N-acetylcysteine (NAC) conjugates of (E)-2,4-diene VPA (NAC I and NAC II) identified in humans. The assay also includes the analysis of the NAC conjugate of 4,5-epoxy VPA (NAC III), an identified metabolite in rats treated with 4-ene VPA for its use in metabolic studies in animals. The highly sensitive GC/MS assay was designed to monitor selectively the diagnostic and most abundant [M - 181](-) fragment anion of the di-PFB derivatives of NAC I, NAC II, and NAC IV, the internal standard (IS) and the PFB derivative of NAC III. The higher selectivity of LC/MS/MS methodology was the basis for an assay which could identify and quantitate the underivatized conjugates simultaneously using MRM of the diagnostic ions m/z 130 and 123 arising from the CID of their protonated molecular ions [MH](+). The GC/MS assay employed liquid-liquid extraction whereas the LC/MS/MS assay used a solid-phase extraction procedure. Linearity ranges of the calibration curves were 0.10-5.0microg ml(-1) by GC/MS and 0.10-1.0microg ml(-1) by LC/MS/MS for NAC I, NAC II and NAC III (r(2) = 0.999 or better). Both assays were validated for NAC I and NAC II and provided good inter- and intra-assay precision and accuracy for NAC I and NAC II. The LOQ by LC/MS/MS was 0.1microg ml(-1), representing 1 ng of NAC I and NAC II. The same LOQ (0.1microg ml(-1)) was observed by GC/MS and was equivalent to 100 pg of each metabolite. NAC III was detected at concentrations as low as 0.01 microg ml(-1) by both methods. The total urinary excretion of the NAC conjugates in four patients on VPA therapy was determined to be 0.004-0.088% of a VPA dose by GC/MS and 0.004-0. 109% of a VPA dose by LC/MS/MS.     

Determination of four nitroimidazoles in poultry and swine muscle and eggs by liquid chromatography/tandem mass spectrometry

A rapid method is presented for the determination of 4 nitroimidazoles in poultry and swine muscle and eggs by liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS). Samples were extracted with acetonitrile, then evaporated the organic phase. After filtration, the extract was directly injected into the LC/ESI-MS/MS system. The LC separation was made on a C8 column by applying a gradient composed of water and acetonitrile. Overall average recoveries ranged from 50-86% for egg, 66-115% for poultry muscle, and 79-111% for swine muscle. The decision limits ranged from 0.05-0.25 microg/kg for egg, 0.07-0.27 microg/kg for poultry muscle, and 0.07-0.26 microg/kg for swine muscle; and detection capabilities ranged from 0.51-0.68 microg/kg for egg, 0.41-0.75 microg/kg for poultry muscle, and 0.53-0.78 microg/kg for swine muscle.     

Determination of chloramphenicol residues in bee pollen by liquid chromatography/tandem mass spectrometry

A novel liquid chromatographic/tandem mass spectrometric (LC/MS/MS) method was developed for the trace residue determination of chloramphenicol (CAP) in bee pollen. CAP was extracted from bee pollen with a mixture of methanol and 1% metaphosphoric acid solution, followed by a 2-stage solid-phase extraction enrichment and cleanup. The first stage involved a polymeric cartridge, and the second stage involved an alumina neutral cartridge. The LC separation was performed on a C18 column with 10 mM ammonium formate-acetonitrile (7 + 3) as the mobile phase and MS detection with negative-ion electrospray ionization. CAP-d5 was used as the internal standard. The method was validated according to Commission Decision 2002/657/EC. The calibration curves were linear between 0.1 and 5.0 ng/mL, and overall recoveries ranged from 98 to 113%. Decision limits (CCalpha) ranged from 0.05 to 0.07 microg/kg, and detection capabilities (CCbeta) ranged from 0.08 to 0.12 microg/kg. The developed method was applied to 11 samples.     

Determination of arsenic species in water, soils and plants

Ion chromatographic separation coupled with ICP-MS was used to determine arsenic species in plant and soil extracts. A scheme for growth, harvesting, sample pre-treatment and analysis was developed for the arsenic species to enable determination. Preliminary results obtained with ten herb plants grown on arsenic-contaminated soil compared to non-contaminated soil show a heterogeneous pattern of accumulation rate, metabolization and detoxification mechanisms in monocots and dicots. Arsenite appears to be the major component in plants with good growth. Organic arsenic species were even detected at very low concentrations (< 150 microg kg(-1) (dry mass)).     

Characterisation of commercially available linear alkylbenzenesulfonates by LC-SPE-NMR/MS (liquid chromatography-solid phase extraction-nuclear magnetic resonance spectroscopy-mass spectroscopy)

Commercially available linear alkylbenzenesulfonates (LASs) are a mixture of various homologues and isomers, leading to 20 major species. In this work we investigated the commercial product by liquid chromatography-solid phase extraction-nuclear magnetic resonance spectroscopy-mass spectrometry (LC-SPE-NMR/MS). The commercial product was separated into 17 fractions by liquid chromatography (LC). After chromatographic separation, 5% of the flow was split to a mass spectrometer (MS) while 95% was send to post-column solid phase extraction cartridges for enrichment of the analytes (LC-SPE). After elution from the SPE-cartridges a NMR-spectrometer equipped with a cryo-probe was used for the characterisation of the different LASs species. For the first time ¹H-1D and H-H-COSY spectra for 14 LASs species out of 20 major isomers are presented, whereas the 6 remaining species are detected as mixtures in 3 ¹H-1D and H-H-COSY spectra. These data were used to correlate the chromatographic retention of the LASs isomers to the substitution pattern of the alkyl chain.