Gas Chromatography-atomic Absorption Spectrometry Research Articles

Characterization of Arsenic Biotransformation Products from an Open Anaerobic Degradation of Fucus distichus by Hydride Generation Gas Chromatography Atomic Absorption Spectrometry and High Performance Liquid Chromatography Inductively Coupled Plasma Mass Spectrometry

This work reports on the isolation and determination of biotransformation products obtained from the organoarsenic compounds that are present in Fucus distichus when it was subjected to an open anaerobic decomposition by using the Hydride Generation Gas Chromatography Atomic Absorption Spectrometry (HG-GC-AAS) and High Performance Liquid Chromatography Inductively Coupled Plasma Mass Spectrometry (HPLC-ICP-MS). The seaweed and filtrate residues obtained from the open anaerobic degradation procedure were extracted in methanol and partitioned in phenol-ether-water mixtures to obtain water soluble extracts. The water soluble extracts were cleaned up and separated on a gel permeation Sephadex G15 column. Arsenic species concentrations were determined by using HG-GC-AAS. Final characterization of the biotransformation isolates was carried out on HPLC-ICP-MS. Only two arsenic species, 2-dimethylarsinoyl ethanol (DMAE) and dimethylarsinic acid (DMAA), were positively identified in the water soluble extract of the marine brown algae. The two arsenic species are strong intermediate candidates in the biosynthesis of arsenobetaine from oceanic arsenate in marine food webs.

Closed Anaerobic Biotransformation Products of Organoarsenic Compounds inFucus distichus

The closed anaerobic decomposition extracts ofFucus distichusincubated with seawater and sediment, and without sediment as control, were subjected to extractions and isolation on Sephadex LH 20 and Cellulose Thin Layer Chromatography. The decomposition extracts and isolates were analyzed by using both the Hydride Generation Gas Chromatography Atomic Absorption Spectrometry (HG-GC-AAS) and High Performance Liquid Chromatography Inductively Coupled Plasma Mass Spectrometry (HPLC-ICPMS) to identify the arsenic species in the equilibrium mixtures of the seaweed and filtrates separately. In the methanol seaweed extract, equilibrium mixture of arsenosugars (AS) AS1 and AS2 and their biotransformation products of dimethylarsinoylethanol (DMAE) and dimethylarsinic acid (DMAA) were identified. In the methanol filtrate extract of the mixture, only DMAE and DMAA were identified. However, in the control methanol filtrate extract five organoarsenic species, AS1 and AS2, one unidentified hidden organoarsenic species, DMAE and DMAA were identified in the equilibrium mixture. This result confirmed that the hidden organoarsenic species inFucus distichus, AS1 and AS2, and an unidentified organoarsenic compounds are biotransformed to only DMAE and DMAA under an anaerobic condition. This also suggests that DMAE and DMAA are strong intermediate candidates for the generation of arsenobetaine, from arsenoribosides in the marine food webs.

Methodology and Application of the Derivative Atomic Absorption Spectrometry

The mathematical models are established for conventional atomic spectrometric signals by simulating experimental results with computer. The laboratory-made derivative measurement system is described. The mathematical models of derivative signals are developed for flame atomic absorption spectrometry (FAAS), cold vapour atomic absorption spectrometry (CVAAS), hydride generation atomic absorption spectrometry(HGAAS) and flow injection flame atomic absorption spectrometry (FIFAAS) and gas chromatography atomic absorption spectrometry (GCAAS). The intensity of derivative signal is in direct relation to concentration of analyte with a good linearity. A theoretical principle is developed for derivative-FAAS, derivative-FAES, derivative-CVAAS, derivative-HGAAS derivative-FIFAAS, and derivative- GCAAS. The performance and application of the derivative atomic absorption spectrometry in trace element analysis are reviewed. Keywords: Signal models, Derivative technique, Principle, Atomic absorption spectrometry, Application

Determination of antimony and the differential determination of antimony(III) and antimony(V) by ICP-AES and high-resolution ICP-MS with a hydride generation technique

Simple methods for the chemical speciation of antimony and organotin compounds were developed by atomic spectroscopy. Antimony was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and high-resolution inductively coupled plasma mass spectrometry (ICP-MS) with a hydride generation technique. Stibine generated with sodium tetrahydroborate(III) (SBH) in a mixing coil was separated from solution with a spiral tube in a closed vessel. The antimony contents of River Arakawa were determined by the present methods. Antimony(III) and antimony(V) were determined differentially by ICP-AES and ICP-MS. Antimony(III) was determined at pH 5.5, while the total antimony was determined at pH 1.0 using potassium iodide as a prereductant. It was found by ICP-MS that the antimony(III) contents of River Arakawa increased while the antimony(V) contents decreased while descending down-stream. Tributyltin and triphenyltin in fish were determined by gas chromatography-atomic absorption spectrometry (GC-AAS) with hydride generation. Fish meat was homogenized in a hydrochloric acid solution of 8-quinolinol. The chlorides in fish were extracted into hexane. After the solvent had been converted to 2-propanol, the solution was applied to a Bondesil SCX solid sorbent. The organotin compounds were eluted with a methanol solution of hydrochloric acid and determined by GC-AAS after hydradization with SBH. The organotin chlorides are supposed to form ion-associates with 8-hydroquinolinium cation in a hydrochlic acid medium.

Speciation of tin, arsenic and antimony species by using hydride generation and reaction kinetics coupled with ICP-AES and ICP-MS

Tin was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and high resolution-inductively coupled plasma mass spectrometry (ICP-MS) with a hydride generation technique. Stannane generated with sodium tetrahydroborate(III) (SBH) was separated from solution with a spiral tube in a closed vessel. The tin content in marine materials was determined by the present methods. Antimony(III) and antimony(V) were determined by ICP-AES or ICP-MS using the pre-reduction of antimony with L-cysteine. Also, arsenic(III) and arsenic(V) were determined by ICP-MS combined with the pre-reduction of arsenic. Tributyltin and triphenyltin in marine sediments were determined by gas chromatography-atomic absorption spectrometry (GC-AAS) with hydride generation. The chlorides in sediments spiked with a hydrochloric acid solution of 8-quinolinol were extracted into toluene. After the solvent had been converted to ethanol, it was applied to a Bondesil SCX. The organotin compounds were eluted with a methanol solution of hydrochloric acid and determined by GC-AAS after hydridization.

Speciation of organotin compounds in marine sediments by capillary column gas chromatography-atomic absorption spectrometry coupled with hydride generation.

A method for speciation of organotin compounds in marine sediments by solvent extraction combined with hydride generation gas chromatography-atomic absorption spectrometry has been developed. Sediment samples spiked with tributyltin and triphenyltin chlorides were homogenized in hydrochloric acid. The chlorides were extracted twice into toluene. Recoveries of the organotin compounds from the spiked sediment samples were improved by the addition of 8-quinolinol. Tributyltin and triphenyltin chlorides form ion-associates with 8-quinolinol in aqueous hydrochloric acid. The method was optimized with respect to derivatization reactions and extraction conditions. Interferences from Sn(II/IV) and additional 13 ions were investigated. Recoveries of 84-100% for tributyltin and 86-100% for triphenyltin were achieved using this method. The detection limits obtained for tributyltin and triphenyltin chlorides were 95 and 145 pg, respectively, corresponding to a relative detection limit of 95 and 145 ng kg(-1) in the sediment.

Formation of involatile methylantimony species by Clostridium spp

Trimethylantimony was detected by gas chromatography–mass spectrometry (GC–MS) in the headspace of a soil enrichment culture designed to promote growth of clostridia. Clostridial isolates from the soil enrichment culture were shown to biomethylate inorganic antimony in monseptic culture, using hydride generation–gas chromatography–atomic absorption spectrometry (HG–GC–AAS). GC–MS profiles of headspace gases from soil enrichment cultures shown to generate trimethylantimony, were used to select characterised Clostridium spp for assessment of antimony biomethylation capability. Involatile methylantimony species (up to 21 μg Sb dm −3) were detected by HG–GC–AAS in the medium of monoseptic cultures of C. acetobutylicum, C. butyricum and C. cochlearium. The relative quantities of involatile mono-, di- and trimethylantimony species produced over the course of a 28-day cultivation period is consistent with trimethylantimony oxide being a final product of antimony biomethylation by these bacteria, with mono- and dimethylantimony species appearing transiently in the cultures as intermediates of an antimony biomethylation pathway. Clostridia may be the principal agents of antimony biomethylation in methanogenic environments and could give rise to methylated forms of antimony in both the aqueous and gaseous phases.

In situ propylation of ionic organotin and organolead species in water samples – Extraction and determination of the resulting tetraorganometallic compounds by gas chromatography-atomic absorption spectrometry

In situ propylation of ionic organotin and organolead species in water samples – Extraction and determination of the resulting tetraorganometallic compounds by gas chromatography-atomic absorption spectrometry

In situ propylation of ionic organotin and organolead species in water samples - Extraction and determination of the resulting tetraorganometallic compounds by gas chromatography-atomic absorption spectrometry

An analytical method for the simultaneous in situ derivatization of organotin and organolead compounds in water samples is described. Propylated derivatives of the analytes formed directly in the aqueous medium by reaction with tetrapropylborate ions are extracted by hexane/pentane. The organic layer is dried and purified with sodium sulfate, concentrated by evaporation of the solvent, and injected into a coupled gas chromatography-atomic absorption spectrometry system. The organotin and organolead compounds are determined sequentially. The optimum parameters for the derivatization and extraction procedures of in situ butylation of organolead compounds developed earlier could be successfully applied to the in situ propylation.

Determination of Organotin Compounds in Fish by Gas Chromatography-Atomic Absorption Spectrometry Using 8-Quinolinol as a Complexing Agent

Recoveries of tributyltin and triphenyltin chlorides spiked in fish were improved by addition of 8-quinolinol. Fish samples spiked with tributyltin and triphenyltin chlorides were homogenized with hydrochloric acid. The chlorides were extracted twice into hexane. After centrifugation, a 2-propanol solution of the chlorides were adsorbed to Bondesil SCX and eluted with a methanol solution of 1 M hydrochloric acid. The chlorides were hydradized with an ethanol solution of sodium tetrahydroborate(III) and injected into a gas chromatography–atomic absorption spectrometer. Tributyltin and triphenyltin chlorides in an NIES Certified Reference Material (sea bass) were determined by the proposed procedure. The analytical results were close to the certified and reference values, respectively. Low recoveries were obtained when monobutyltin and dibutyltin chlorides were spiked with and without 8-quinolinol. Tributyltin and triphenyltin chlorides are supposed to form ion-associates with 8-quinolinol in an aqueous solution of hydrochloric acid. The detection limits (three times the signal-to-noise ratio) of tributyltin and triphenyltin chlorides were 105 and 165 pg, respectively.

Speciation of inorganic and organolead compounds by gas chromatography-atomic absorption spectrometry and the determination of lead species after pre-concentration onto diphenylthiocarbazone-anchored polymeric microbeads

Poly(EGDMA-HEMA) microbeads were prepared by suspension copolymerization of ethyleneglycol dimethacrylate (EGDMA) and hydroxyethylmethacrylate (HEMA) using poly(vinylalcohol), benzoyl peroxide and toluene as the stabilizer, the initiator, and the diluent, respectively. A chelating ligand, diphenylthiocarbazone (dithizone), was then attached. The microbeads were characterized by FT-IR and elemental analysis. The affinity microbeads containing 118.9 μmol dithizone g −1 polymer were used in the adsorption/desorption of some selected lead species, Pb(II), (CH 3) 2PbCl 2, (C 2H 5) 2PbCl 2, (CH 3) 3PbCl, and (C 2H 5) 3PbCl from aqueous media containing different amounts of these species (5–200 mg l −1) at different pH values, 2.0–8.0. Adsorption rates were high, and adsorption equilibrium was reached in approximately 45 min. The detection limits of the lead species onto the dithizone-anchored affinity microbeads from solutions containing a single species was 0.28 ng ml −1 for Pb(II), 0.12 ng ml −1 for (CH 3) 3PbCl, 0.24 ng ml −1 for (C 2H 5) 3PbCl, 0.18 ng ml −1 for (CH 3) 2PbCl 2 and 0.30 ng ml −1 for (C 2H 5) 2PbCl 2 on a weight basis for lead. The same behavior was observed during competitive adsorption that is adsorption from a mixture. The affinity order of the lead species was Pb(II)>(CH 3) 2PbCl 2>(CH 3) 3PbCl>(C 2H 5) 3PbCl>(C 2H 5) 2PbCl 2 for competitive adsorption. Dithizone-anchored microbeads were found to be suitable for repeated use of more than five cycles, without noticeable loss of adsorption capacity. For the speciation of organolead compounds, ionic alkyllead compounds were derivatized by n-butyl Grignard reagent and the speciation was performed using a gas chromatography-atomic absorption spectrometry coupled system. Detection limits were improved at least 180-fold with this preconcentration approach using the dithizone-anchored microbeads.

Analytical potential of fullerene as adsorbent for organic and organometallic compounds from aqueous solutions

In this work, the analytical potential of C 60 fullerene as a sorbent for organic and organometallic compounds from aqueous solutions was studied for the first time. Fullerene adsorbs many types of organic substances (e.g., N-methylcarbamates, phenols, polycyclic aromatic hydrocarbons, amines) with efficiencies that depend on the nature of the compound concerned and never exceed 60%. Conventional sorbents such as XAD-2 or polyurethane foam are more efficient than C 60 for this purpose. Organometallic compounds (viz. metalocenes and organoleads) are quantitatively adsorbed on C 60 via the formation of neutral complexes or chelates; the adsorption constant is dramatically increased by the use of classical reagents such as pyrrolidinedithiocarbamate or diethyldithiocarbamate. A complementary comparative study on the adsorption of organometallic complexes on RP-C 18 and silica gel 100, among others, showed C 60 to be superior as sorbent. All experiments in this work were carried out by using continuous flow configurations and gas chromatography–atomic absorption spectrometry techniques.

Determination of inorganic and organic mercury compounds by capillary gas chromatography coupled with atomic absorption spectrometry after preconcentration on dithizone-anchored poly(ethylene glycol dimethacrylate-hydroxyethylmethacrylate) microbeads

Poly(EGDMA-HEMA) microbeads were prepared by suspension polymerization of ethylene glycol dimethacrylate (EGDMA) and hydroxyethyl methacrylate (HEMA). Poly(vinyl alcohol), benzoyl peroxide and toluene were used as stabilizer, initiator, and diluent, respectively. A chelating ligand, dithizone, was then attached. The microbeads were characterized by FTIR spectrometers and elemental analysis. The affinity microbeads containing 118.9 μmol dithizone g −1 polymer were used for the adsorption/desorption of inorganic mercury [Hg], methyl mercury chloride [CH 3HgCl] and ethyl mercury chloride [C 2H 5HgCl] from aqueous media at concentrations in the range 5–1000 μg l −1 and various pH values (2.0–8.0). Adsorption rates were high, and adsorption equilibria were reached in about 30 min. The maximum adsorption of mercury species onto the dithizone-anchored microbeads from their individual solutions was 138 mg g −1 for Hg(II), 221 mg g −1 for CH 3HgCl and 207 mg g −1 for C 2H 5HgCl. The same behavior was observed during competitive adsorption in the case of the adsorption from their mixture. The affinity order of mercury species was CH 3HgCl > C 2H 5HgCl > Hg(II). Dithizone-anchored microbeads are suitable for repeated use for more than 5 cycles without noticeable loss of adsorption capacity. Speciation of organomercurials was performed using a Gas chromatography-atomic absorption spectrometry coupled system. Detection limits were increased at least 120-fold with this preconcentration approach using the dithizone-anchored microbeads.

Demethylation of trimethylantimony species in aqueous solution during analysis by hydride generation/gas chromatography with AAS and ICP MS detection

The method of hydride generation for the speciation of antimony compounds was examined with respect to the problem of molecular rearrangement'. Specifically, demethylation of trimethylstilbine during the analysis of trimethylantimony dichloride (Me3SbCl2) was studied. Previously published observations that enhanced demethylation takes place as a result of inadequate preconditioning of the analytical apparatus were found to be not reproducible. However, demethylation was enhanced as the pH decreased when using two different analytical methods: semi-continuous flow hydride generation–gas chromatography–atomic absorption spectrometry (HG– GC–AAS), and batch-type hydride generation– gas chromatography–inductively coupled plasma mass spectrometry (HG–GC–ICP MS). Applications of the hydride generation method to environmental samples revealed differences in analytical results at high and low pH, and enhanced demethylation taking place because of the matrix in a fungal extract sample. The authors recommend that researchers using the method of hydride generation for antimony compounds carefully test the reaction conditions with standard compounds and use the method of standard addition only. © 1998 John Wiley & Sons, Ltd.

Determination of methylmercury in biological samples and sediments by capillary gas chromatography coupled with atomic absorption spectrometry after hydride derivatization and solid phase microextraction

A method for the extraction and determination of methylmercury in biological samples and sediments by solid phase microextraction (SPME) combined with capillary gas chromatography–atomic absorption spectrometry (GC–AAS) has been proposed. The methylmercury chloride was converted to its hydride form by potassium tetrahydroborate (KBH4) in a closed headspace vial prior to extraction. A laboratory-assembled SPME device including a capillary fused-silica fiber and a modified microsyringe was used throughout the experiment. The extraction is an equilibrium process that depends on the methylmercury hydride partitioning between the liquid phase and the fiber. When the equilibrium was reached, the fiber was directly transferred to a GC column by means of the microsyringe, where the analyte was thermally desorbed inside a heated injector and subsequently the column effluent was atomized by a heated stainless steel tube and detected by an on-line coupled AAS. Several factors affecting the SPME procedure such as fiber pretreatment with hydrofluoric acid, pH buffering, addition of salt and sampling time have been investigated and optimized. The reproducibility of the SPME procedure was 91% and the detection limit based on the signal equal to 3 times the baseline noise, was 26 ng. The method was applied to determination of methylmercury in biological samples and sediments.

Determination of butyltins in harbour sediment and water by aqueous phase ethylation GC-ICP-MS and hydride generation GC-AAS

Sediment and water samples have been collected between 1992 and 1995 for evaluating butyltin contamination in two marinas from the coastal area in The Netherlands, two years after the ban of TBT. Sediments extracts were analysed by capillary gas chromatography-inductively coupled plasma-mass spectrometry. Sediment concentrations for TBT showed no trend of decrease between 1992 and 1995 and were extremely high in the marina secluded from tidal action; 17.5 ± 8.0 μg g −1 and much lower for the marina with tidal action; 0.117 ± 0.073 μg g −1. High ratios between TBT and DBT in the sediments indicate that degradation mechanisms in the sediments are of minor importance. Dissolved butyltin compounds were analysed in water by means of gas chromatography-atomic absorption spectrometry. Water concentrations of TBT showed no clear trend of decrease between 1992 and 1995 and were high in the marina secluded from tidal action; 139 ± 166 ng litre −1 but much lower for the marina with tidal action; 48 ± 98 ng litre −1. An active degradation mechanism during summer periods was indicated by low (<1) TBT/DBT ratios in the water phase of the marina secluded from tidal action.

Organotin Leachates in Drinking Water from Chlorinated Poly(vinyl chloride) (CPVC) Pipe

A solid-phase extraction method, using a phenyl-bonded silica sorbent, was developed for the isolation of mono- and di-methyltin, -butyltin and -octyltin from drinking water. Recoveries averaged 92% over two tested sample weights and spiking levels. Ethyl derivatives were made by Grignard reaction for determination by gas chromatography–atomic absorption spectrometry (GC–AAS). Static and repetitive extraction studies were conducted at 24 and 65°C. Butyltins rapidly leached into drinking water kept in chlorinated poly(vinyl chloride) (CVPC) pipe samples. Monobutyltin and dibutyltin levels reached 19.8 (13.4 as Sn) and 197 (100.4 as Sn) ng g−1 respectively in water samples collected from CPVC pipe heated to 65°C. Butyltins were still leached from CPVC pipe after 20 repetitive extractions, suggesting that new CPVC water systems would contaminate water with organotins for some time after installation. © 1997 John Wiley & Sons, Ltd.

Organotin Leachates in Drinking Water from Chlorinated Poly(vinyl chloride) (CPVC) Pipe

A solid-phase extraction method, using a phenyl-bonded silica sorbent, was developed for the isolation of mono- and di-methyltin, -butyltin and -octyltin from drinking water. Recoveries averaged 92% over two tested sample weights and spiking levels. Ethyl derivatives were made by Grignard reaction for determination by gas chromatography–atomic absorption spectrometry (GC–AAS). Static and repetitive extraction studies were conducted at 24 and 65°C. Butyltins rapidly leached into drinking water kept in chlorinated poly(vinyl chloride) (CVPC) pipe samples. Monobutyltin and dibutyltin levels reached 19.8 (13.4 as Sn) and 197 (100.4 as Sn) ng g−1 respectively in water samples collected from CPVC pipe heated to 65°C. Butyltins were still leached from CPVC pipe after 20 repetitive extractions, suggesting that new CPVC water systems would contaminate water with organotins for some time after installation. © 1997 John Wiley & Sons, Ltd.

Intercomparison of alkyllead compound determination in mussels and water by two analytical techniques: Gas chromatography atomic absorption spectrometry and differential pulse anodic stripping voltammetry

Methods for the determination of tetraalkyllead (TAL) and ionic alkyllead (IAL) compounds in mussel tissues are described with each step in the procedures critically evaluated. It was established that digestion of mussel tissue with tetramethylammonium hydroxide should be performed at room temperature to avoid decomposition of some alkylleads, that TAL and IAL compounds should be extracted and determined separately, and that for extraction into hexane and re-extraction into acid aqueous solution, a double extraction must be used. Cleaning of extracts through a silica column is recommended before gas chromatography atomic absorption spectrometry (GC AAS) measurement. Determination of IAL compounds in environmental samples (mussel tissue and various kinds of natural waters) by two independent analytical techniques (GC AAS and DP ASV — differential pulse anodic stripping voltammetry) is compared.

Signal-to-noise ratios for coupled gas chromatography–atomic absorption spectrometry using quartz tube atomizers

A study of coupled gas chromatography–atomic absorption spectrometry (GC–AAS) was undertaken in an effort to identify the operating conditions and quartz tube (QT) atomizer dimensions yielding optimum signal-to-noise (S/N) ratios. Tetramethyllead (TML) and tetraethyllead (TEL) were chosen as test analytes and separated by temperature-programmed GC using a wide-bore capillary column. The noise level was dependent only on the limiting aperture in the optical train, defined by either the design of the spectrometer system or, at conditions maximizing the S/N ratios, by the dimensions of the QT atomizer. The atomizer dimensions also affected the signal magnitude, as did the gas flow rate and composition and the standard deviation of the (assumed) Gaussian peak, sG, eluting from the GC system. A physical model describing the S/N ratio in terms of these operating variables was developed and verified experimentally for TML and TEL using five QT atomizer configurations. The S/N ratios were shown, both experimentally and theoretically, to improve using chromatographic conditions that minimize sG. Optimum QT atomizer dimensions for a range of operating conditions are tabulated.