Fast determination of arsenosugars in algal extracts by narrow bore high-performance liquid chromatography-inductively coupled plasma mass spectrometry

The potential of narrow bore high-performance liquid chromatography (HPLC) with detection by inductively coupled plasma mass spectrometry (ICP-MS) for fast determination of arsenosugars in algal extracts was explored. The retention behavior of four naturally occurring dimethylarsinoylribosides on an anion-exchange microbore column was investigated, with the mobile phase flow rate ranging from 60 to 200μLmin(-1). A low sample consumption system consisting of a micronebulizer and a low inner volume cyclonic spray chamber was used as the interface between the micro-column and the ICP mass spectrometer. Both the high efficiency nebulizer, HEN, and the PFA micronebulizer were tested, with the former providing 20-50% greater sensitivity than PFA (depending on the liquid flow rate), but comparable limits of detection and slightly lower chromatographic resolution. With the setup employed and under the optimal conditions, a satisfactory separation of the arsenosugars was achieved in less than 5min. The instrumental limit of detection was 0.20μgAsL(-1) and the precision was better than 3% (RSD%, n=5). The accuracy of the determination was verified by the analysis of a reference algal extract, obtaining values in good agreement with the reference ones.     

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.     

Critical review or scientific opinion paper: Arsenosugars—a class of benign arsenic species or justification for developing partly speciated arsenic fractionation in foodstuffs?

In this opinion paper the toxicokinetic behaviour of arsenosugars is reviewed and compared with that of inorganic arsenic and arsenobetaine. It is concluded that the arsenosugars are similar to inorganic arsenic in terms of metabolite formation and tissue accumulation. As a pragmatic means of generating uniform data sets which adequately represent the toxicity of arsenic in food we recommend reporting partly speciated arsenic concentrations in food commodities in three fractions: i) toxic inorganic arsenic as arsenate (after oxidation); ii) arsenobetaine as established non-toxic arsenic; and iii) potentially toxic arsenic, which includes arsenosugars and other organoarsenicals.     

高效液相色谱-电感耦合等离子体质谱联用技术测定干海产品中砷化学形态

利用高效液相色谱-电感耦合等离子体质谱联用技术研究了海带、羊栖菜、紫菜及浒苔等干海产品中的砷含量及其化学形态.实验表明,干海产品中主要砷形态为3种未知砷化物,对3种未知砷化物进行了表征.采用高效液相色谱与飞行时间质谱联用技术对羊栖菜和海带中的3种未知砷化物的分子量,分别为329.0599, 483.0738和409.0162,通过对比,确定这3个未知峰分别为3种砷糖类物质: DMA-glycerol ribose, DMA-phosphate ribose和DMA-sulfate ribose.对样品中砷的定量分析结果显示,干海产品中砷总量虽然超出我国国标中关于海产品中砷限量标准规定的20倍以上,但大多数植物性干海产品中主要的砷形态为毒性较低的砷糖类物质DMA-sulfate ribose(U4),其含量约占可提取砷量的51.1%～80.3%,海带中的砷主要以DMA-phosphate ribose(U3)的形式存在,占总可提取砷的48.9%.     

Liquid chromatography electrospray mass spectrometry with variable fragmentor voltages gives simultaneous elemental and molecular detection of arsenic compounds

A single quadrupole high performance liquid chromatography electrospray mass spectrometry system with a variable fragmentor voltage facility was used in the positive ion mode for simultaneous recording of elemental and molecular mass spectral data for arsenic compounds. The method was applicable to the seven organoarsenic compounds tested: four arsenic-containing carbohydrates (arsenosugars), a quaternary arsonium compound (arsenobetaine), dimethylarsinic acid, and dimethylarsinoylacetic acid. It was not suitable for the two inorganic arsenic species arsenite and arsenate. In the case of arsenosugars, qualifying ion data for a characteristic common fragment (m/z 237) was also simultaneously obtained. The method was used to identify and quantify the major arsenosugars in crude extracts of two brown algae.     

Biodegradation of arsenosugars in marine sediment

In the marine environment, arsenic accumulates in seaweed and occurs mostly in the form of arsenoribofuranosides (often called arsenosugars). This study investigated the degradation pathways of arsenosugars from decaying seaweed in a mesocosm experiment. Brown seaweed (Laminaria digitata) was placed on top of a marine sediment soaked with seawater. Seawater and porewater samples from different depths were collected and analysed for arsenic species in order to identify the degradation products using high‐performance liquid chomatography–inductively coupled plasma mass spectrometry. During the first 10 days most of the arsenic found in the seawater and the shallow sediment is in the form of the arsenosugars released from the seaweed. Dimethylarsenoylethanol (DMAE), dimethylarsinic acid (DMA(V)) and, later, monomethylarsonic acid (MMA(V)) and arsenite and arsenate were also formed. In the deeper anaerobic sediment, the arsenosugars disappear more quickly and DMAE is the main metabolite with 60–80% of the total arsenic for the first 60 days besides a constant DMA(V) contribution of 10–20% of total soluble arsenic. With the degradation of the soluble DMAE the solubility of arsenic decreases in the sediment. The final soluble degradation products (after 106 days) were arsenite, arsenate, MMA(V) and DMA(V). No arsenobetaine or arsenocholine were identified in the porewater. Copyright © 2005 John Wiley & Sons, Ltd.     

Two-dimensional HPLC coupled to ICP-MS and electrospray ionisation (ESI)-MS/MS for investigating the bioavailability in vitro of arsenic species from edible seaweed

Edible seaweed consumption is a route of exposure to arsenic. However, little attention has been paid to estimate the bioaccessibility and/or bioavailability of arsenosugars in edible seaweed and their possible degradation products during gastrointestinal digestion. This work presents first use of combined inductively coupled plasma mass spectroscopy (ICP-MS) with electrospray ionization tandem mass spectrometry (ESI-MS/MS) with two-dimensional HPLC (size exclusion followed by anion exchange) to compare the qualitative and quantitative arsenosugars speciation of different edible seaweed with that of their bioavailable fraction as obtained using an in vitro gastrointestinal digestion procedure. Optimal extraction conditions for As species from four seaweed namely kombu, wakame, nori and sea lettuce were selected as a compromise between As extraction efficiency and preservation of compound identity. For most investigated samples, the use of ammonium acetate buffer as extractant and 1 h sonication in a water bath followed by HPLC-ICP-MS resulted in 40–61% of the total As to be found in the buffered aqueous extract, of which 86–110% was present as arsenosugars (glycerol sugar, phosphate sugar and sulfonate sugar for wakame and kombu and glycerol sugar and phosphate sugar for nori). The exception was sea lettuce, for which the arsenosugar fraction (glycerol sugar, phosphate sugar) only comprised 44% of the total extracted As. Interestingly, the ratio of arsenobetaine and dimethylarsinic acid to arsenosugars in sea lettuce extracts seemed higher than that for the rest of investigated samples. After in vitro gastrointestinal digestion, approximately 11–16% of the total As in the solid sample was found in the dialyzates with arsenosugars comprising 93–120% and 41% of the dialyzable As fraction for kombu, wakame, nori and sea lettuce, respectively. Moreover, the relative As species distribution in seaweed-buffered extracts and dialyzates was found to be very similar. Collection of specific fractions from the size-exclusion column to be analysed using anion-exchange HPLC-ESI-MS/MS enabled improved chromatographic selectivity, particularly for the less retained arsenosugar (glycerol sugar), facilitating confirmation of the presence of arsenosugars in seaweed extracts and dialyzates. Using this approach, the presence of arsenobetaine in sea lettuce samples was also confirmed.     

Determination of an arsenosugar in oyster extracts by liquid chromatography-electrospray mass spectrometry and liquid chromatography-ultraviolet photo-oxidation-hydride generation atomic fluorescence spectrometry

HPLC-UV-HG-AFS analysis of aqueous extracts of oysters (Crassostrea gigas) taken from the southwestern Atlantic coast of Spain showed the presence of arsenite, arsenate, dimethylarsinic acid and an unidentified arsenic peak. Subsequent analysis of the oyster samples by LC-electrospray MS and comparison with four standard dimethylarsinoylribosides (arsenosugars), showed that the previously unidentified peak was an arsenosugar (arsenosugar 2). When the arsenosugar in the oyster was quantified using the two detection methods and external calibration with standard arsenosugar, there was a large discrepancy between the two sets of results. The LC-MS analysis was strongly affected by the sample matrix and gave concentrations 50% lower than those obtained by AFS detection. When the method of standard addition was applied to the LC-MS analysis, the results were comparable to the AFS data. The matrix effects were eliminated by subjecting the extract to a clean-up procedure with anion-exchange and gel permeation preparative chromatography before the LC-MS analysis. The arsenosugars gave a small signal without photo-oxidation when they were analysed by HPLC-HG-AFS. Possibly this resulted from partial decomposition of the arsenosugar to dimethylarsinic acid under the acidic conditions employed in the hydride generation step.     

Speciation of dimethylarsinyl-riboside derivatives (arsenosugars) in marine reference materials by HPLC-ICP-MS

Anion and cation exchange HPLC-ICP-MS was used to separate and detect mixtures of four dimethylarsinyl-riboside derivatives (arsenosugars), in the presence of eight other arsenic species naturally occurring in the marine environment. The separations achieved showed that two arsenosugars 11 and 13 (cf. Table 2) were present in shellfish certified reference materials (CRMs) and in a lobster hepatopancreas CRM. The concentration of the two arsenosugars in the shellfish samples amounts to 18% of the total arsenic as compared to arsenobetaine at 9–13% and dimethylarsinate at 4–9% of the total arsenic. Additionally, a chromatographic peak with the same retention time as that of 2-dimethylarsinylacetic acid was detected in the shellfish samples. Further support of the identity of this peak was gained after spiking the sample extracts with the standard substance which resulted in a single, but larger peak. The indication that this novel arsenical is present in shellfish, and the recently reported finding of arsenocholine in seafood supports a proposed marine biosynthetic pathway of arsenic that includes both of these compounds as the immediate precursors of arsenobetaine, the end-product of the marine arsenic metabolism.     

Transformation of arsenic(V) by the fungus Fusarium oxysporum melonis isolated from the alga Fucus gardneri

A fungus isolated from the macroalga Fucus gardneri was identified by using 28S rDNA sequence analysis, 99% similarity match, as Fusarium oxysporum meloni. The fungus was exposed to arsenic(V) (500 ppb) in artificial seawater to investigate the possibility that the fungus is the source of the metabolic activity that results in the presence of arsenosugars in the macroalga. High‐performance liquid chromatography coupled with inductively coupled plasma mass spectrometry was used to identify the arsenic species in the fungus, and in the growth medium. The fungus was able to accumulate arsenic(V) and an increase in arsenite and dimethylarsinate was also observed. Some reduction of arsenate led to a small increase of arsenite in the growth medium. The fungus does not seem to be involved with the accumulation of arsenosugars by the Fucus. Copyright © 2002 John Wiley & Sons, Ltd.     

An investigation of the chemical stability of arsenosugars in simulated gastric juice and acidic environments using IC-ICP-MS and IC-ESI-MS/MS

A more quantitative extraction of arsenic-containing compounds from seafood matrices is essential in developing better dietary exposure estimates. More quantitative extraction often implies a more chemically aggressive set of extraction conditions. However, these conditions may result in undesirable chemical changes in the native arsenicals which may further complicate the toxicological risk assessment. This balance between quantitative extraction and species-specific integrity may be best addressed by using simulated gastric juice as an extraction solvent to mimic 'bioavailability'. This, conceptually, should extract the bioavailable fraction and induce any chemical changes that would occur because of ingestion. The most chemically labile species associated with seafood are thought to be the arsenosugars and for this reason their chemical stability is investigated in this study. Four arsenosugars (3-[5'-deoxy-5'-(dimethylarsinoyl)-beta-ribofuranosyloxy]-2-hydroxypropylene glycol, As(328); 3-[5'-deoxy-5'-(dimethylarsinoyl)-beta-ribofuranosyloxy]-2-hydroxypropanesulfonic acid, As(392); 3-[5'-deoxy-5'-(dimethylarsinoyl)-beta-ribofuranosyloxyl-2-hydroxypropyl hydrogen sulfate, As(408); and 3-[5'-deoxy-5'-(dimethylarsinoyl)-beta-ribofuranosyloxy]-2-hydroxypropyl-2,3-hydroxypropyl phosphate, As(482)) were isolated from seaweed extracts and subjected to simulated gastric juice and acidic conditions which mimic the stomach's pH of 1.1. Three acid solutions were used to test the chemical stability of the arsenosugars: simulated gastric juice, 78 mM nitric acid and 78 mM hydrochloric acid. The composition of the solutions was monitored over time (up to 48 h) using IC-ICP-MS for detection. The arsenosugars were found to degrade at the rate of 1.4% per h at 38 degrees C and 12.2% per h at 60 degrees C. The plots of percent conversion versus time were found to be independent of the starting arsenosugar and all had r2 values of greater than 0.97. A single common degradation product was observed in all the stability studies. A mass balance between the starting arsenosugar (As(392), As(408) and As(482)) and the degradation product was conducted with each set of experiments. This mass balance indicated that the degradation process did not produce any unchromatographable species. This degradation product was tentatively identified as As(254) as determined by ESI-MS/MS spectral data. An acid hydrolysis mechanism was proposed for the formation of As(254) from each of the native arsenosugars by hydrolysis at the C-1 carbon on the ribose ring.     

Nitrogen purity influences the occurrence of As+ ions in high-performance liquid chromatography/electrospray ionization mass spectrometric analysis of four common arsenosugars

High-performance liquid chromatography coupled to electrospray ionization mass spectrometry (HPLC/ESI-MS) can provide both elemental and molecular information and, therefore, is a very useful tool for the identification of arsenic compounds. When a method for the identification of four arsenosugars was employed in our laboratory with an HPLC/ESI-MS system equipped with a Whatman model 75-72 nitrogen generator, a signal at m/z 75 (As(+)) could not be observed. When the HPLC/ESI-MS system was operated with nitrogen 5.0 (nitrogen of a purity of at least 99.999%) all four arsenosugars gave a signal at m/z 75. Because of this observation the influence of the quality of the nitrogen drying gas on the fragmentation of the four arsenosugars was systematically investigated. Standard solutions containing the four arsenosugars (0.5 ng As each) were separated on an anion-exchange column and detected with ESI-MS in the positive ion mode by monitoring the signals for [M+H](+), m/z 237, 91, and 75. Nitrogen with defined oxygen concentrations was used as drying gas. The purity of the nitrogen ranged from 99 to 99.999% (10 400 to 10 ppm oxygen impurity). The nitrogen with 99% purity gave no signal at m/z 75, but signals were obtained at m/z 91, 237, and for [M+H](+). When higher purity nitrogen (99.9%) was used, a signal was obtained at m/z 75, which accounted for 0.8-1.1% (depending on the kind of arsenosugar) of the sum of the signals for m/z 75, 91, 237 and [M+H](+). As the level of oxygen in the nitrogen decreased, the m/z 75 signal increased to 2.0-3.1%. This was accompanied by a concomitant decrease in the m/z 91 signal from 5.2-6.6% to 0.7-1.5%, whereas the signals for [M+H](+) and m/z 237 were essentially unchanged. Signals at m/z 75 with intensities comparable with those observed for the 99.9% pure nitrogen were also obtained for all the arsenosugars when the HPLC/ESI-MS system was operated with a Domnick Hunter Nitrox UHPLCMS18 nitrogen generator. Dimethylarsinic acid, arsenobetaine, trimethylarsine oxide, arsenocholine and the tetramethylarsonium cation also gave no signal at m/z 75 when they were analyzed with the Whatman model 75-72 nitrogen generator, but clear signals at m/z 75 were observed with the Domnick Hunter Nitrox UHPLCMS18 nitrogen generator. A nitrogen quality of at least 99.9% is required to obtain elemental information (m/z 75) when arsenic compounds are investigated by HPLC/ESI-MS. Molecular and elemental information from one chromatographic run is a valuable tool for the characterization of unknown arsenic compounds.     

Thio arsenosugars identified as natural constituents of mussels by liquid chromatography-mass spectrometry

Two novel thio arsenosugars have been identified by liquid chromatography-mass spectrometry as significant arsenic constituents in samples of mussels.     

Simultaneous separation of 17 inorganic and organic arsenic compounds in marine biota by means of high-performance liquid chromatography/inductively coupled plasma mass spectrometry

A method using high-performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC/ICP-MS) has been developed to determine inorganic arsenic (arsenite, arsenate) along with organic arsenic compounds (monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, arsenocholine, trimethylarsine oxide, tetramethylarsonium ion and several arsenosugars) in fish, mussel, oyster and marine algae samples. The species were extracted by means of a methanol/water mixture and a dispersion unit in 2 min, with extraction efficiencies ranging from 83 to 107% in the different organisms. Up to 17 different species were determined within 15 min on an anion-exchange column, using a nitric acid gradient and an ion-pairing reagent. As all species are shown in one chromatogram, a clear overview of arsenic distribution patterns in different marine organisms is given. Arsenobetaine is the major compound in marine animals whereas arsenosugars and arsenate are dominant in marine algae. The method was validated with CRM DORM-2 (dogfish muscle). Concentrations were within the certified limits and low detection limits of 8 ng g(-1) (arsenite) to 50 ng g(-1) (arsenate) were obtained.     

First report on the detection and quantification of arsenobetaine in extracts of marine algae using HPLC-ES-MS/MS

The detection of arsenobetaine in extracts of marine algae is reported here for the first time. The application of liquid chromatography coupled online with electrospray tandem mass spectrometry in the selected reaction monitoring mode provided improved performance for the detection of low amounts of arsenobetaine in the presence of high amounts of arsenosugars.     

An investigation of the chemical stability of arsenosugars in basic environments using IC-ICP-MS and IC-ESI-MS/MS

This paper evaluates the chemical stability of four arsenosugars using tetramethylammonium hydroxide (TMAOH) as an extraction solvent. This solvent was chosen because of the near quantitative removal of these arsenicals from difficult to extract seafood (oysters and shellfish). Four arsenosugars (3-[5'-deoxy-5'-(dimethylarsinoyl)-beta-ribofuranosyloxy]-2-hydroxypropylene glycol--As(328), 3-5'-deoxy-5'-(dimethylarsinoyl)-beta-ribofuranosyloxy]-2-hydroxypropanesulfonic acid--As(392), 3-[5'-deoxy-5'-(dimethylarsinoyl)-beta-ribofuranosyloxy]-2-hydroxypropyl hydrogen sulfate--As(408), and 3-[5'-deoxy-5'-(dimethylarsinoyl)-beta-ribofuranosyloxy]-2-hydroxypropyl-2,3-hydroxypropyl phosphate--As(482)) were evaluated. The stability of these four arsenosugars were studied independently in a solution of 2.5% TMAOH at 60 degrees C over a period of up to 8 h. Two arsenosugars, As(328) and As(392), were found to be relatively stable in this solution for up to 8 h. However, As(408) and As(482) formed detectable quantities of dimethylarsinic acid (DMAA) and As(328) within 0.5 and 2 h, respectively. It was found that 97% of As(408) degrades after 8 h of treatment producing 3.4 times as much DMAA as As(328). This is contrary to As(482), which produces 13 times as much As(328) as DMAA and only 37% of the As(482) was converted by the 8 h treatment at 60 degrees C. These degradation products led to the investigation of weaker TMAOH extraction solvents. Three different concentrations (2.5%, 0.83% and 0.25%) were used to determine the effect of TMAOH concentration on the degradation rate of As(408). By reducing the TMAOH concentration to 0.83%, the conversion of the arsenosugar to As(328) and DMAA is nearly eliminated (less than 5% loss). Arsenosugars, As(408) and As(482), were also studied in 253 mM NaOH to verify the degradation products. The NaOH experiments were conducted to investigate a possible hydroxide based reaction mechanism. Similar degradation plots were found for each arsenosugar when compared to the 2.5% TMAOH data. A mechanism has been proposed for the formation of As(328) from As(408) and As(482) in base via an SN2 reaction (hydroxide attack) at the side chain carbon adjacent to the inorganic ester. The formation of DMAA is observed in all arsenosugars after prolonged exposure. This probably occurs via an SN2 attack at the arsenic atom.     

Precursor ion scanning for the non-targeted detection of individual arsenosugars in extracts of marine organisms

Arsenosugars are a group of arsenic compounds reported to be present in a wide variety of marine organisms. Numerous such compounds have been identified and characterized in marine organisms; however, unknown arsenosugar species may also be present. This indicates the need for an analytical technique suitable for their non-targeted detection. One such technique is tandem mass spectrometry operated in the precursor ion scanning mode. This technique is based on scanning for precursor ions that give specific product ions, characteristic of the compounds under investigation. In the present study two subgroups of arsenosugar species were examined, the oxo- and the thioarsenosugars, the CID behavior of which is well known from previous studies. In the case of the oxoarsenosugars characteristic product ions were observed at m/z 237 and 97, and for the thioarsenosugars at m/z 253 and 97. Validation of this approach was carried out by analyzing extracts of two commercial kelp powders with known contents of arsenosugar species. All arsenosugars reported to exist in these materials were detected successfully using the precursor ion scanning approach. The limits of detection for the oxo- and the thioarsenosugar species, and the selectivity and sensitivity of the method, strongly indicate the suitability of this approach for the non-targeted detection of arsenosugars in extracts of marine origin.     

Determination of Arsenic in Algae – Results of an Interlaboratory Trial: Determination of Arsenic Species in the Water-Soluble Fraction

Seven algae samples, five purchased from food stores and two reference algae (BCR 279 Sea Lettuce) were distributed as blind samples to 13 laboratories from which five labs attempted a full characterisation of the water-soluble fraction with respect to their arsenic species. The extraction efficiency is largely dependant on the algae and varied from 3% to 96%. Besides inorganic arsenic (mainly as As^(V)) DMA^(V) and, in particular, several arsenosugars were identified in all samples. From the five labs, three labs gave agreeable results in respect of the arsenic species identification and its quantification, although different chromatographic methods were used. Different Hijiki samples seem to contain largely different arsenic concentration (67–113 mg As/kg) which may also have an influence on the distribution of inorganic arsenic and arsenosugars.     

Biotransformation of arsenate to arsenosugars by Chlorella vulgaris

Chlorella vulgaris was cultivated in a growth medium containing arsenate concentration of <0.01, 10, 100 and 1000 mg l^?1. Illumination was carried out in 12 h cycles for 5 days. The health status of the culture was monitored by continuous pH and dissolved oxygen (DO) readings. Destructive sampling was used for the determination of biomass, chlorophyll, total arsenic and arsenic species. The chlorophyll a content, the DO and pH cycles were not significantly different for the different arsenate concentrations in the culture. In contrast, biomass production was significantly (p < 0.05) increased for the arsenic(V) treatment at 1000 mg l^?1 compared with 100 mg l^?1. The arsenic concentration in the algae increased with the arsenate concentration in the culture. However, the bioconcentration factor decreased a hundred‐fold with increase of arsenate from the background level to 1000 mg l^?1. The arsenic species were identified by using strong anion‐exchange high‐performance liquid chromatography–inductively coupled plasma mass spectrometry analysis after methanol/water (1 : 1) extraction. The majority (87–100%) of the extractable arsenic was still arsenate; arsenite was found to be between 1 and 6% of total extractable arsenic in the algae. In addition to dimethylarsinic acid, one unknown arsenical (almost co‐eluting with methylarsonic acid) and three different arsenosugars have been identified for the first time in C. vulgaris growing in a culture containing a mixture of antibiotics and believed to be axenic. The transformation to arsenosugars in the algae is not dependent on the arsenate concentration in the culture and varies between 0.2 and 5% of total accumulated arsenic. Although no microbiological tests for bacterial contamination were made, this study supports the hypothesis that algae, and not associated bacteria, produce the arsenosugars. Copyright © 2003 John Wiley & Sons, Ltd.     

现代仪器分析技术在纺织品及皮革分析中的应用

现代分析技术以仪器分析为主,大量先进的现代仪器分析技术已经广泛地应用于纺织品及皮革分析。介绍了气相色谱（GC）、液相色谱（LC）、色谱质谱联用（GC-MS、LC-MS）、原子吸收（AAS）、电感耦合等离子发射光谱（ICP-OES）等现代仪器分析技术在纺织品及皮革分析中的研究进展与应用。