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.     

Determination of aldehydes in fish by high-performance liquid chromatography

A new analytical method to determine trace volatile aldehydes isolated from the headspace of fish meat at room temperature by high-performance liquid chromatography (HPLC) in the form of 2,4-dinitrophenylhydrazone (DNPHo) derivatives has been developed. Aliquots (50 g) of the fish purée were introduced into a 500-mL glass recipient and were purged with N2 for 40 min through two SEP-PAK C18 cartridges (connected in series) coated with an acid solution of 2,4-dinitrophenylhydrazine. The cartridges were then eluted with acetonitrile (2 mL) and the 2,4-DNPHo formed was quantitated by HPLC-UV analysis using a Zorbax C18 column. The isolated compounds from the dynamic headspace sampling of four kinds of fish species were saturated aldehydes, formaldehyde, acetaldehyde, propanal, butanal, pentanal, and hexanal. Under optimized conditions the detection limits of the HPLC method were in the range of 0.75 nmol/g (formaldehyde) to 2.19 nmol/g (hexanal). The calibration curves were linear in the concentration range from 1.3 nmol/mL to 12.5 nmol/mL. Propanal and acetaldehyde were the major carbonyl compounds identified (ranging from 3.9 nmol/g and 10 nmol/g). This study has revealed the widespread occurrence of formaldehyde, acetaldehyde, propanal, butanal, pentanal, and hexanal in fish meat.     

Perry G. Wang (Ed.): Monolithic chromatography and its modern applications

Organic micropollutants such as pharmaceuticals, perfluorinated compounds (PFCs), and pesticides, are important environmental contaminants. To obtain more information regarding their presence in marine organisms, an increasing demand exists for reliable analytical methods for quantification of these micropollutants in biotic matrices. Therefore, we developed extraction procedures and new analytical methods for the quantification of 14 pesticides, 10 PFCs, and 11 pharmaceuticals in tissue of marine organisms, namely blue mussels (Mytilus edulis). This paper presents these optimized analytical procedures and their application to M. edulis, deployed at five stations in the Belgian coastal zone. The methods consisted of a pressurized liquid extraction and solid-phase extraction (SPE) followed by ultra high-performance liquid chromatography coupled to triple quadrupole mass spectrometry for pharmaceuticals and pesticides, and of a liquid extraction using acetonitrile and SPE, followed by liquid chromatography coupled to time-of-flight mass spectrometry for PFCs. The limits of quantification of the three newly optimized analytical procedures in M. edulis tissue varied between 0.1 and 10 ng g(-1), and satisfactory linearities (≥0.98) and recoveries (90-106%) were obtained. Application of these methods to M. edulis revealed the presence of five pharmaceuticals, two PFCs, and seven pesticides at levels up to 490, 5, and 60 ng g(-1), respectively. The most prevalent micropollutants were salicylic acid, paracetamol, perfluorooctane sulfonate, chloridazon, and dichlorvos.     

Speciation of butyltin compounds in marine sediments with headspace solid phase microextraction and gas chromatography mass spectrometry

A method for the determination of organotin compounds (monobutyl = MBT, dibutyl = DBT, and tributyltin = TBT) in marine sediments by headspace Solid Phase Microextraction (SPME) has been developed. The analytical procedure involved 1) extraction of TBT, DBT and MBT from sediments with HCl and methanol mixture, 2) in situ derivatization with sodium tetraethylborate and 3) headspace SPME extraction using a fiber coated with poly(dimethylsiloxane). The derivatized organotin compounds were desorbed into the splitless injector and simultaneously analyzed by gas chromatography - mass spectrometry. The analytical method was optimized with respect to derivatization reaction and extraction conditions. The detection limits obtained for MBT, DBT and TBT ranged from 730 to 969 pg/g as Sn dry weight. Linear calibration curves were obtained for all analytes in the range of 30-1000 ng/L as Sn. Analysis of a standard reference sediment (CRM 462) demonstrates the suitability of this method for the determination of butyltin compounds in marine sediments. The application to the determination of TBT, DBT and MBT in a coastal marine sediment is shown.     

Speciation of butyltin compounds in marine sediments with headspace solid phase microextraction and gas chromatography – mass spectrometry

A method for the determination of organotin compounds (monobutyl = MBT, dibutyl = DBT, and tributyltin = TBT) in marine sediments by headspace Solid Phase Microextraction (SPME) has been developed. The analytical procedure involved 1) extraction of TBT, DBT and MBT from sediments with HCl and methanol mixture, 2) in situ derivatization with sodium tetraethylborate and 3) headspace SPME extraction using a fiber coated with poly(dimethylsiloxane). The derivatized organotin compounds were desorbed into the splitless injector and simultaneously analyzed by gas chromatography – mass spectrometry. The analytical method was optimized with respect to derivatization reaction and extraction conditions. The detection limits obtained for MBT, DBT and TBT ranged from 730 to 969 pg/g as Sn dry weight. Linear calibration curves were obtained for all analytes in the range of 30–1000 ng/L as Sn. Analysis of a standard reference sediment (CRM 462) demonstrates the suitability of this method for the determination of butyltin compounds in marine sediments. The application to the determination of TBT, DBT and MBT in a coastal marine sediment is shown.     

Report on three aliphatic dimethylarsinoyl compounds as common minor constituents in marine samples. An investigation using high-performance liquid chromatography/inductively coupled plasma mass spectrometry and electrospray ionisation tandem mass spectrometry

Three water-soluble aliphatic arsenicals, dimethylarsinoyl acetate (DMAA), dimethylarsinoyl ethanol (DMAE), and dimethylarsinoyl propionate (DMAP), were identified in marine biological samples. Sample extracts in methanol/water (1 + 1) were analysed by cation-exchange high-performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC/ICPMS). Eluate fractions from the HPLC/ICPMS analyses containing the compounds in question were collected and subjected to analysis by electrospray ionisation tandem mass spectrometry (ESI-MS/MS), which provided supportive evidence for the structures of the three compounds. The concentrations of the three arsenicals were determined in 37 marine organisms comprising algae, crustaceans, bivalves, fish and mammals by HPLC/ICPMS. The three arsenicals DMAA, DMAE and DMAP, which occurred at microg kg(-1) concentrations, were detected in 25, 23 and 17 of the 37 samples analysed, respectively. The limits of detection were 2-3 microg kg(-1) dry mass. The data illustrate that the three compounds are common minor constituents in marine samples. This is the first report on DMAE and DMAP as naturally occurring species in marine samples. The presence of DMAA and DMAE supports a proposed biosynthesis of arsenobetaine (AB) from dimethylarsinoylribosides. Alternative proposals, which explain the presence of the compounds in marine samples, are addressed briefly in the paper.     

Measurement of beta-carbolines by high-performance liquid chromatography with fluorescence detection

A method using high-performance liquid chromatography with fluorescence detection was developed for the determination of beta-carboline compounds norharman, harman, norharmol, and harmol in lung. Aqueous derivatization with acetic anhydride was used to facilitate the isolation and separation of the phenolic compounds and to reduce the fluorescence background of the biological samples. Harman was identified and quantitated in rat lung (1.88 +/- 0.55 ng/g) using this method and its identity confirmed by means of gas chromatography-negative-ion chemical ionization mass spectrometry.     

The identification of some water-soluble arsenic species in the marine brown algae Fucus distichus

The extraction and clean-up procedures developed to isolate the water-soluble arsenic species present in the marine macroalga Fucus distichus, from British Columbia, Canada, are described. The arsenic species were extracted into methanol and then subjected to gel-permeation and ion-exchange chromatography. Fractions high in arsenic were identified by using graphite furnace atomic absorption spectroscopy (GF-AAS), and further investigated by using high-performance liquid chromatography coupled to inductively coupled plasma–mass spectrometry (HPLC–ICP MS). By using different HPLC columns and mobile-phase conditions, the four major arsenic-containing compounds present in the macroalga were positively identified as arsenosugars; one minor compound remained unidentified. © 1997 John Wiley & Sons, Ltd.     

Feasibility study: fast liquid chromatography–mass spectrometry for the quantification of aspartic acid in an aspartate drug

We have studied the feasibility of fast high-performance liquid chromatography coupled to electrospray ionization mass spectrometry in the selected ion monitoring mode for the quantitative determination of aspartic acid in an aspartate drug. Internal standardization was required, but mass spectrometric detection allowed for very short retention times of approximately 0.5 min for the analyte and the internal standard without chromatographic separation. The analytical system was found stable, as demonstrated by multiple injections giving a coefficient of variation of 4% for the peak area ratio of aspartic acid and glutamic acid. Calibrations were linear between 0.5 ng and 150 ng aspartic acid injected, with accuracies between 99.8% and 102% found for the back-calculated amounts. Investigation of several drug batches gave reasonable results. Therefore, the method appeared feasible for the determination of aspartic acid in an aspartate drug from 0.3 wt% to 100 wt% aspartic acid.Abbreviations CV coefficient of variation - ESI electrospray ionization - HPLC high-performance liquid chromatography - HSGC headspace gas chromatography - KaFi Karl Fischer titration - MS mass spectrometry - MSD mass-selective detector - % m/m percentage by weight - PAR peak area ratio - r² coefficient of determination - RP reversed-phase - SIM selected ion monitoringThis work was originally presented as a poster at the Conference of the German Society for Mass Spectrometry, 9–12 March 2003, in Münster, Germany     

Analysis of xanthohumol and isoxanthohumol in different hop products by liquid chromatography-diode array detection-electrospray ionization tandem mass spectrometry

An analytical methodology based on the sample extraction with methanol/formic acid by ultra-sonication and subsequent analysis by high-performance liquid chromatography with diode array detection is proposed for the determination of xanthohumol (XN) and isoxanthohumol (IXN) in different hop products. The identity of the compounds was confirmed by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry in positive ion mode. The performance of the method was assessed by the evaluation of parameters such as absolute recovery, repeatability, linearity and limits of detection and quantitation. This methodology was applied to investigate the impact of the extraction process of the hop products on the amount of xanthohumol and isoxanthohumol. The ethanolic extract revealed to be the hop product richest in xanthohumol (3.75+/-0.05 g/100 g) relatively to the pellets (0.62+/-0.01 g/100 g) and supercritical CO2 extract (0.089+/-0.001 g/100 g).     

Sample pretreatment method for the determination of polychlorinated biphenyls in bird livers using ultrasonic extraction followed by headspace solid-phase microextraction and gas chromatography-mass spectrometry

A simple and reliable sample methodology based on simultaneous ultrasonic extraction, sulfuric acid clean-up and headspace solid-phase microextraction (SPME)-gas chromatography-mass spectrometry has been developed as an advantageous analytical tool for the determination of seven polychlorinated biphenyl congeners in bird livers at low levels. The influence of several parameters on the efficiency of the proposed method was systematically investigated. The clean-up efficiency of sulfuric acid treatment was tested and compared with those of column chromatography (Flosiril, silica gel and alumina) and solid-phase extraction (SPE) (Supelclean ENVI-Carb cartridge) procedures. The use of sulfuric acid in the clean-up step prior to headspace solid-phase microextraction analysis allows the removal of interfering matrix compounds present in the liver extracts that would otherwise cause severe ionization suppression of the polychlorinated biphenyls (PCBs) during the ionization process. The optimized method had good linearity (R2>0.99) over the range studied (5-500 ng/g wet weight) and showed satisfactory level of precision, with RSD values lower than 10.6%. The obtained relative recoveries ranged between 63 and 94%. The limits of detection (0.06-0.63 ng/g wet weight) were low enough to check for harmful levels of polychlorinated biphenyls in biological samples, and were well below most of the restrictive limits established by European Union regulations. The method was found to be reliable under the operational conditions proposed and was applied successfully to the analysis of individual polychlorinated biphenyls in liver tissues. The results obtained from five bird species from Greece revealed the presence of the target compounds in all samples analyzed, at levels ranging between 0.54 and 39.45 ng/g wet weight.     

HPLC–QTOF–MS/MS-based rapid screening of phenolics and triterpenic acids in leaf extracts of Ocimum species and their interspecies variation

Species of genus Ocimum are traditionally used for their medicinal and flavoring properties. These are rich sources of essential oils and found as an ingredient in many Ayurvedic preparations and food products. Phenolics and triterpenic acids are the medicinally active compounds mainly concentrated in the leaves of Ocimum species. This study aimed to develop an efficient and reliable analytical method for the rapid screening and characterization of phenolics and triterpenic acids in the leaf extracts of 6 Ocimum species using high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (HPLC–ESI–QTOF–MS/MS). A total of 50 compounds were identified and characterized on the basis of their accurate MS and MS/MS information, out of which 23 compounds were confirmed by authentic standards. Identified compounds include 28 flavonoids, 4 propenyl phenol derivatives, 2 triterpenic acids, 11 phenolic acids, and 5 phenolic acid esters. The developed method was applied to study the interspecies variation of identified compounds. Significant variation in the distribution of identified phenolics and triterpenic acids was observed among studied Ocimum species. Hence, the established method provides an effective and reliable tool for screening and characterization of phytoconstituents in Ocimum species.     

Determination of phenols in environmental samples by liquid chromatography – electrochemistry

A reverse-phase high-performance liquid chromatography procedure with gradient elution and electrochemical detection is described for the determination of phenolic compounds, including several priority pollutant chlorophenols, in sea-water and sediments. In addition, a method for concentrating phenols from sea-water was examined. A solid-phase extraction using a derivatized poly(styrene-divinylbenzene) copolymer is discussed. The recovery, repeatability and detection limits are shown. Electrochemical detection provided selectivity as well as sensitivity. Phenols at the ng/l level were detected. The method was applied to the analysis of the most important phenolic compounds in sea-water and marine sediments.     

Solid phase microextraction as a tool for trace element speciation

Applications of solid phase microextraction (SPME) for trace element speciation are reviewed. Because of the relative novelty of the technique in the inorganic analytical field, the first part of this review provides a short overview of the principles of SPME operation; the second part describes typical SPME applications to elemental speciation. Volatile organometallic compounds can be collected by SPME from the sample headspace or liquid phase, directly or after derivatization. The usual separation method for the collected volatile species is gas chromatography. Non-volatile analyte species can be collected from the sample liquid phase and separated by liquid chromatography or capillary electrophoresis. Currently, most SPME applications in the inorganic field comprise analyte ethylation and headspace extraction followed by gas chromatographic separation of tin, lead and mercury species. The use of SPME for the study of equilibria in complex systems is also discussed and future roles of solid phase microextraction in the inorganic analytical field are raised.     

Determination of microcystins in blue-green algae, fish and water using liquid chromatography with ultraviolet detection after sample clean-up employing immunoaffinity chromatography

Anti-microcystin LR immunnoaffinity cartridges were evaluated for their ability to selectively remove microcystins from extracts of blue-green algae, fish and water samples for subsequent analysis by liquid chromatography with UV absorbance detection at 238 nm. Blue-green algae and fish samples were extracted with 75% methanol in water. A portion of the extract was diluted and passed through an immunoaffinity cartridge. Water samples were applied directly to the cartridge. The cartridge was rinsed with water and 25% methanol in water. The microcystins were eluted with 80% methanol in water containing 4% acetic acid. It was found that the cartridges were effective in isolating the microcystins from blue-green algae, fish and water samples, resulting in extracts that were clean enough to enable direct LC-UV detection down to approximately 0.03 microg/g in the blue-green algae and fish samples, and as low as 0.02 ng/ml for water samples. The cartridges were found to have a capacity of approximately 200 ng each for a mixture of microcystins RR, YR, LR and LA, or as much as 525-800 ng for individual compounds. Recoveries trough the complete analytical procedure ranged from 64 to 115% (all values) with an overall average of approximately 80% at spiking levels of 0.5-4.0 microg/g for the microcystins in blue-green algae. The average recoveries (n=8) from spiked (0.1-0.5 microg/g) fish samples were 73% for RR, 79% for YR, 81% for LR and 77% for LA, while from the spiked (2.0-0.04 ng/g) tap and river water samples (n=6), recoveries were 78% for RR, 86% for YR, 94% for LR and 89% for LA.     

Determination of phenols in environmental samples by liquid chromatography – electrochemistry

A reverse-phase high-performance liquid chromatography procedure with gradient elution and electrochemical detection is described for the determination of phenolic compounds, including several priority pollutant chlorophenols, in sea-water and sediments. In addition, a method for concentrating phenols from sea-water was examined. A solid-phase extraction using a derivatized poly(styrene-divinylbenzene) copolymer is discussed. The recovery, repeatability and detection limits are shown. Electrochemical detection provided selectivity as well as sensitivity. Phenols at the ng/l level were detected. The method was applied to the analysis of the most important phenolic compounds in sea-water and marine sediments. Received: 12 April 1996 / Revised: 30 October 1996 / Accepted: 28 November 1996     

Speciation of arsenic in chicken meat by anion-exchange liquid chromatography with inductively coupled plasma-mass spectrometry

A method was developed for speciation analysis of arsenic in chicken meat. Different procedures were optimized for the recovery of arsenic compounds without destroying the original compounds, and 2 anion-exchange liquid chromatography columns were compared for the separation of arsenic species prior to on-line detection by inductively coupled plasma-mass spectrometry. The 2 species found were dimethylarsinic acid (106 +/- 5 ng/g) and arsenobetaine (37 +/- 4 ng/g). The stability of arsenic species in a chicken meat candidate reference material for at least 12 months was demonstrated.     

Improved analysis of ladderane lipids in biomass and sediments using high-performance liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry

Ladderane lipids, containing three or five linearly concatenated cyclobutane moieties, are considered to be unique biomarkers for the process of anaerobic ammonium oxidation, an important link in the oceanic nitrogen cycle. Due to the thermal lability of the strained cyclobutane moieties, the ladderane lipids are difficult to analyze by gas chromatography. A method combining high-performance liquid chromatography coupled to positive ion atmospheric pressure chemical ionization tandem mass spectrometry (HPLC/APCI-MS/MS) was developed for the analysis of the most abundant ladderane lipids, occurring as fatty acids and ether-bound to glycerol. Detection was achieved by selective reaction monitoring of four specific fragmentations per ladderane lipid. Detection limits of 30-35 pg injected on-column and a linear response (r(2) > 0.99) over nearly 3 orders of magnitude were achieved for all compounds. Using this method, these unique ladderane lipids were for the first time identified in a surface sediment from the Gullmarsfjorden, in concentrations ranging from 1.1-5.5 ng/g for the ladderane fatty acids and of 0.7 ng/g for the monoether. It is foreseen that this method will allow the investigation of the occurrence of anaerobic ammonium oxidation in natural settings in much greater detail than before.     

非水反相高效液相色谱法测定海藻中3种叶黄素类化合物

建立了非水反相高效液相色谱测定不同种类海藻中3种叶黄素类化合物的方法。采用超声波辅助提取海藻中的叶黄素类化合物,选用Alltima C18色谱柱分离,以甲醇-乙腈-丙酮为流动相系统,梯度洗脱分离,检测波长445 nm。结果表明,在选定的色谱条件下,待分析的3种叶黄素类化合物与其他化合物分离良好,在一定浓度范围内线性关系良好(紫黄素:6.24～624μg/L,环氧玉米黄素:4.56～456μg/L,玉米黄素:5.60～560μg/L)。该方法适用于不同海洋藻类中3种叶黄素类化合物的定量分析。