Determination of butyltin and octyltin stabilizers in poly(vinyl chloride) products by headspace solid-phase microextraction and gas chromatography with flame-photometric detection

Headspace solid-phase microextraction (HS-SPME) and gas chromatography with flame photometric detection (GC-FPD) have been investigated for determination of butyltin and octyltin stabilizers in poly(vinyl chloride) (PVC) products. The organotin stabilizers were first released from the plastic matrix by dissolving the PVC sample in tetrahydrofuran (THF). The stabilizers were then hydrolyzed to the chloride forms, by treatment with 6 mol L⁻¹ HCl, then derivatized with sodium tetraethylborate (NaBEt₄) in 0.2 mol L⁻¹ sodium acetate buffer (pH 4.5) at 50 °C. HS-SPME was performed with a fused-silica fiber coated with a 100-μm film of polydimethylsiloxane (PDMS). The collected organotin compounds were then desorbed in the GC injector at 280 °C and analyzed by GC-FPD. Linearity (r≥0.994) over a concentration of approximately two orders of magnitude was usually obtained. Limits of quantitation (LOQ) of the four organotin compounds studied, viz., monobutyltin (MBT), dibutyltin (DBT), monooctyltin (MOT), and dioctyltin (DOT), were in the range 0.3–1.0 ng Sn mL⁻¹. Recovery was >90% for butyltins and >80% for octyltins. The method was validated by analyzing two reference standard PVC sheets with known organotin content. The applicability of the method to analysis of organotin stabilizers in commercial PVC products was also demonstrated.     

Solid-phase extraction-liquid chromatography-fluorimetry for organotin speciation in natural waters

Summary A method is reported for the determination of dibutyltin (DBT), diphenyltin (DPhT), tributyltin (TBT), and triphenyltin (TPhT) species at the nanogram per litre concentration level in natural water samples. Analytes were isolated from samples by solid-phase extraction and analysed both off-line and on-line by reversed-phase high-performance liquid chromatography with post-column derivatization and fluorimetric detection. Several SPE cartridges and eluents were evaluated; C₁₈ enrichment and elution with a mixture of methanol, acetic acid, and water was found most suitable. Preconcentration factors up to 250 can be achieved when a 500-mL sample is processed. Detection limits, recovery rates, and the precision of the whole process have been determined. The method has been applied to the determination of organotin species in spiked natural water samples collected on the NW Mediterranean coast. Recovery rates range from 75 to 110% and detection limits are at the low ng L⁻¹ level (1–3 ng Sn L⁻¹ for DPhT, DBT, and PhT and 40 ng Sn L⁻¹ for TBT when 250 mL spiked sea water is processed.)     

Occurrence of cytostatic compounds in hospital effluents and wastewaters,determined by liquid chromatography coupled to high-resolution mass spectrometry

The occurrence of 26 commonly used cytostatic compounds in wastewaters was evaluated using an automated solid-phase extraction (SPE) method with liquid chromatography–high-resolution mass spectrometry (LC–HRMS). Detection was optimized using Oasis HLB SPE cartridges at pH 2. Two hospital effluents and their two receiving wastewater treatment plants were sampled over five days. In hospital effluents, eight cytostatics were detected at levels up to 86.2 μg L^?1 for ifosfamide, 4.72 μg L^?1 for cyclophosphamide, and 0.73 μg L^?1 for irinotecan, the three most relevant compounds identified. Cyclophosphamide and megestrol acetate were found in wastewaters at concentrations up to 0.22 μg L^?1 for the latter. The predicted environmental concentrations (PEC) in sewage effluents of ifosfamide (2.4–4.3 ng L^?1), capecitabine (11.5–14.2 ng L^?1), and irinotecan (0.4–0.6 ng L^?1), calculated from consumption data in each hospital, published excretion values for the target compounds, and wastewater elimination rates, were in agreement with experimental values.     

Determination of Butyltins in Sea Water by Gas Chromatography with Flame Photometric Detection

Use of a gas chromatograph with a flame-photometric detector (GC-FPD) is described to determine butyltin compounds in sea water. The butyltins in an acidified water sample (pH 3.0) are first complexed with tropolone, followed by solid-phase extraction (SPE) with a tropolone-treated C₁₈ cartridge. HCI at a small concentration is then added to the concentrated SPE eluate before GC analysis. This procedure is simple and off-column derivatization of analytes is not required. The organotins, viz. mono-, di- and tributyltin, are separated as their respective chlorides on a capillary column (HP-1) and are detected with a flame-photometric detector and an interference filter at 610 nm. Recoveries of the three butyltin species are quantitative (> 90%). Based on a sea water sample 200-mL, the detection limits for mono-, di- and tributyltin are 6,4 and 3 ng tin L^?1, respectively. This method is applied to analysis of trace butyltins in various samples of sea water.     

Determination and risk assessment of pesticide residues in lake Amvrakia (W. Greece) after agricultural land use changes in the lake's drainage basin

A monitoring study of pesticides belonging to different chemical families was carried out in Amvrakia lake (West Greece) waters after land use changes in the lake's basin. Based on land-use patterns, nine sampling points were selected. Pesticides were extracted by solid phase extraction (SPE) using Oasis HLB cartridges and analysed by gas chromatographic techniques with flame thermionic and mass-spectra detection. Pesticides detected during the monitoring survey include eight herbicides (alachlor, atrazine, s-metolachlor, pendimethalin, prometryne, propachlor, simazine, trifluralin) and one metabolite (deethyl atrazine) with concentration levels up to 807?ng?L^?1 (recorded for alachlor), eight insecticides (azinphos methyl, chlorpyrifos, chlorpyrifos methyl, diazinon, dimethoate, fenitrothion, malathion, methidathion) with concentration levels up to 490?ng?L^?1 (recorded for azinphos methyl) and six fungicides (benalaxyl, cyproconazole, fenarimol, pyrimethanil, triadimefon, triadimenol) with concentration levels up to 408?ng?L^?1 (recorded for pyrimethanil). More frequently detected pesticides were atrazine, deethyl atrazine, alachlor, azinphos methyl, chlorpyrifos methyl, diazinon and pyrimethanil. The higher concentrations were measured during spring-early summer period, following seasonal application of pesticides and diminished significantly during winter. Littoral sampling stations presented higher pesticide concentration levels and more frequent detection. Aquatic risk assessment was based on the Risk Quotient (RQ?=?MEC/PNEC) deterministic method regarding three trophic levels: algae, aquatic invertebrates and fish. Non-acceptable risk for 10 compounds was observed when maximum concentrations were used. Compliance to EC environmental quality standards is also discussed.     

Determination of acidic pharmaceutical products and carbamazepine in roughly primary-treated wastewater by solid-phase extraction and gas chromatography–tandem mass spectrometry

A gas chromatography–tandem mass spectrometry (GC–MS/MS) method has been developed for the determination of selected pharmaceutical residues (carbamazepine, salicylic acid, clofibric acid, ibuprofen, 2-hydroxy-ibuprofen, fenoprofen, naproxen, ketoprofen, diclofenac, and triclosan) in sewage influent and roughly primary-treated effluent. The method involved solid-phase extraction (SPE) with polymeric sorbents, and two SPE cartridges were compared for the extraction and elution of the targeted compounds in complex matrices. A successful chemical derivatization of carbamazepine and acidic compounds using N,O-bis(trimethylsilyl) trifluoroacetamide +10% trimethylchlorosilane is also described. The quantification limits of the analytical procedure ranged from 30 to 60?ng?L^?1 for 500?mL of wastewater. The best recovery rates (72–102%) in spiked effluent samples were obtained with Phenomenex Strata-X? cartridges. Detection limits (S/N?=?3) were estimated at between 1 and 18?ng?L^?1. The reported GC–MS/MS method significantly reduces the strong matrix effects encountered with more expensive LC-MS/MS techniques. Application of the developed method showed that most selected analytes were detected at concentrations ranging from low µg?L^?1 to trace level ng?L^?1 in Montreal's wastewater treatment plant effluent and influent, as well as in the receiving waters at more than 8?km downstream of the effluent outfall. The rugged alternative analytical method is suitable for the simultaneous analysis of carbamazepine and pharmaceutical acidic residues in wastewater samples from influents and effluents that have undergone rough primary treatment.     

Trace analysis of benzophenone-derived compounds in surface waters and sediments using solid-phase extraction and microwave-assisted extraction followed by gas chromatography–mass spectrometry

This study describes a procedure for determining eight benzophenone-derived compounds in surface waters and sediments. These include the pharmaceutical ketoprofen, its phototransformation products 3-ethylbenzophenone and 3-acetylbenzophenone, and five benzophenone-type ultraviolet (UV) filters. The proposed analytical method involves the pre-concentration of water samples by solid-phase extraction (SPE) and microwave-assisted extraction (MAE) of sediment samples followed by derivatization and analysis by gas chromatography–mass spectrometry. Different parameters were investigated to achieve optimal method performance. Recoveries of 91 to 96 % from water samples were obtained using HLB Oasis SPE cartridges, whereas MAE of sediments (30 min at 150 °C) gave recoveries of 80 to 99 %. Limits of detection were between 0.1 and 1.9 ng L^?1 for water samples and from 0.1 to 1.4 ng g^?1 for sediment samples. The developed method was applied to environmental samples and revealed the presence of UV filters in the majority of the surface waters with up to 690 ng L^?1 of 2-hydroxy-4-methoxybenzophenone. By contrast, ketoprofen (≤2,900 ng L^?1) and its degradation products (≤320 ng L^?1) were found in only two rivers, both receiving wastewater treatment plant effluents. Sediment analysis revealed benzophenone to be present in concentrations up to 650 ng g^?1, whereas concentrations of other compounds were considerably lower (≤32 ng L^?1). For the first time, quantifiable amounts of two ketoprofen transformation products in the aqueous environment are reported.     

Preconcentration Ultra Trace of Cd(II) in Water Samples Using Dispersive Liquid‐Liquid Microextraction with Salen(N,N′‐Bis(Salicylidene)‐Ethylenediamine) and Determination Graphite Furnace Atomic Absorption Spectrometry

Dispersive liquid–liquid microextraction (DLLME) technique was successfully used as a sample preparation method for graphite furnace atomic absorption spectrometry (GF AAS). In this extraction method, 500 μL methanol (disperser solvent) containing 34 μL carbon tetrachloride (extraction solvent) and 0.00010 g Salen(N,N′‐bis(salicylidene)ethylenediamine) (chelating agent) was rapidly injected by syringe into the water sample containing cadmium ions (interest analyte). Thereby, a cloudy solution formed. The cloudy state resulted from the formation of fine droplets of carbon tetrachloride, which have been dispersed, in bulk aqueous sample. At this stage, cadmium reacts with Salen(N,N′‐bis(salicylidene)‐ethylenediamine), and therefore, hydrophobic complex forms which is extracted into the fine droplets of carbon tetrachloride. After centrifugation (2 min at 5000 rpm), these droplets were sedimented at the bottom of the conical test tube (25 ± 1 μL). Then a 20 μL of sedimented phase containing enriched analyte was determined by GF AAS. Some effective parameters on extraction and complex formation, such as extraction and disperser solvent type and their volume, extraction time, salt effect, pH and concentration of the chelating agent have been optimized. Under the optimum conditions, the enrichment factor 122 was obtained from only 5.00 mL of water sample. The calibration graph was linear in the range of 2‐21 ng L^?1 with a detection limit of 0.5 ng L^?1. The relative standard deviation (R.S.D._s) for ten replicate measurements of 20 ng L^?1 of cadmium was 2.9%. The relative recoveries of cadmium in tap, sea and rain water samples at a spiking level of 5 and 10 ng L^?1 are 99, 94, 97 and 96%, respectively. The characteristics of the proposed method have been compared with cloud point extraction (CPE), on‐line liquid‐liquid extraction, single drop microextraction (SDME), on‐line solid phase extraction (SPE) and co‐precipitation based on bibliographic data. Therefore, DLLME combined with GF AAS is a very simple, rapid and sensitive method, which requires low volume of sample (5.00 mL).     

C,N-chelated organotin(IV) trifluoroacetates. Instability of the mono- and diorganotin(IV) derivatives.

The C,N-chelated tri-, di- and monoorganotin(IV) halides react with equimolar amounts of CF₃COOAg to give corresponding C,N-chelated organotin(IV) trifluoroacetates. The set of prepared tri-, di- and monoorganotin(IV) trifluoroacetates bearing the L^CN ligand (where L^CN is 2-(N,N-dimethylaminomethyl)phenyl-) was structurally characterized by X-ray diffraction analyses, multinuclear NMR and IR spectroscopy. In the case of triorganotin(IV) trifluoroacetates and (L^CN)₂Sn(OC(O)CF₃)₂, no tendency to form hydrolytic products, or instability towards the moisture was observed. L^CNRSn(OC(O)CF₃)₂ (where R is n-Bu or Ph) and L^CNSn(OC(O)CF₃)₃ forms upon crystallization from THF in the air mainly dinuclear complexes in which the two tin atoms are interconnected either by hydroxo-bridges or by an oxo-bridge and/or by a bridging trifluoroacetate(s). In the case of hydrolysis of L^CN(n-Bu)Sn(OC(O)CF₃)₂, a zwitterionic stannate of formula L^CN(n-Bu)Sn(OC(O)CF₃)₂·CF₃COOH was isolated from the mother liquor, too. Products of hydrolysis of L^CN(n-Bu)Sn(OC(O)CF₃)₂ and L^CNSn(OC(O)CF₃)₃, and some other oxygen bridged organotin(IV) compounds containing the same ligand, were tested as possible catalysts of some transesterification reactions as well as in direct dimethyl carbonate (DMC) synthesis from CO₂ and methanol.     

Determination of organotin compounds by headspace solid-phase microextraction–gas chromatography–pulsed flame-photometric detection (HS-SPME–GC–PFPD)

A method based on Headspace solid-phase microextraction (HS-SPME, with a 100 μm PDMS-fiber) in combination with gas-chromatography and pulsed flame-photometric detection (GC-PFPD) has been investigated for simultaneous determination of eight organotin compounds. Monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), monophenyltin (MPhT), and the semi-volatile diphenyltin (DPhT), triphenyltin (TPhT), monooctyltin (MOcT), and dioctyltin (DOcT) were determined after derivatization with sodium tetraethylborate. The conditions used for the extraction and preconcentration step were optimised by experimental design methodology. Tripropyltin (TPrT) and diheptyltin (DHepT) were used as internal standards for quantification of volatile and semi-volatile organotin compounds, respectively. The analytical precision (RSD) for ten successive injections of a standard mixture containing all the organic tin compounds ranged between 2 and 11%. The limits of detection for all the organotin compounds were sub ng (Sn) L⁻¹ in water and close to ng (Sn) kg⁻¹ in sediments. The accuracy of the method was evaluated by analysis of two certified reference material (CRM) sediment samples. The HS-SPME–GC–PFPD was then applied to the analysis of three harbour sediment samples. The results showed that headspace SPME is an attractive tool for analysis of organotin compounds in solid environmental matrices.     

Molecular modeling for the interaction between proteasome beta 5 subunit and organotin compounds

It has been reported that organotins can inhibit the proteasomal chymotrypsin-like activity and induce cell death, but the interaction mode of organotins with proteasome has not been well defined. In this study, the IC₅₀ of butyltins and phenyltins against the proteasomal activity and the nature of their inhibition were investigated. It was found that both mono- and di-organotins were weak, reversible inhibitors against the proteasome, while tributyltin and triphenyltin were potent, irreversible proteasome inhibitors. In silico studies using the reversible organotin proteasome inhibitors demonstrated a tight correlation of the estimated proteasomal inhibition constants (Ki) with the experimental IC₅₀ values for proteasome inhibition. Furthermore, the Sn atom in TBT and TPT was found susceptible to form a coordinate bond with Thr 1 O^γ of the β5 subunit, which may account for the irreversible proteasome inhibition. The computational docking approach well predicted the inhibition nature of organotins toward the proteasomal chymotrypsin-like activity. This predictive model might aid in understanding the cytotoxic behavior of similar organometallic compounds.     

Determination of phenoxyalkanoic acids and other herbicides at the ng/ml level in water by solid-phase extraction with poly(divinylbenzene-co-N-vinylpyrrolidone) sorbent and high-performance liquid chromatography--diode-array detection

A method for the determination of phenoxyalkanoic acids and other polar compounds in environmental water samples without pH adjustment before extraction has been developed. Recoveries were calculated from 500 ml of milliQ water spiked at the level of 0.5 ng/ml using solid-phase extraction (SPE) and HPLC-DAD. Different SPE materials (RP-C18, ENV+, ENV+-C8, SAX and Oasis HLB) were tested. After method optimization, 15 of the 16 compounds studied could be extracted with recoveries better than 70% on the most suitable copolymeric poly(divinylbenzene-co-N-vinylpyrrolidone) material (Oasis HLB cartridges).     

Evaluation of mixed mode solid phase extraction cartridges for the preconcentration of beta-lactam antibiotics in wastewater using liquid chromatography with UV-DAD detection

A novel and simple method has been developed for the simultaneous determination of beta-lactam antibiotics (BLAs) (penicillin G, amoxicillin, ampicillin, penicillin V, oxacillin, cloxacillin, dicloxacillin and nafcillin) in wastewater. The method is based on solid-phase extraction (SPE) and high performance liquid chromatography with UV-diode array detection (UV-DAD). Two SPE cartridges have been compared for sample clean up and preconcentration: a reversed-phase silica-based cartridge (Bond Elut C₁₈, Varian Inc.) and a strong polymeric mixed mode anion exchanger (Oasis MAX, Waters). The penicillins have been separated using a LUNA™ C₁₈ (2) (150 mm × 4.6 mm, 5 μm) HPLC column and gradient elution with mobile phases consisting of aqueous trifluoroacetic acid and acetonitrile. The analytical wavelength was set at 220 nm. Under optimised conditions it was possible to preconcentrate up to 1000 mL of Milli-Q water in the Oasis MAX cartridges with recoveries in the range 82-97% (R.S.D. 2-9%) for all the antibiotic tested, except amoxicillin (52%, R.S.D. 8%), and limits of detection in the range of 8-24 ng L⁻¹. The matrix components in industrial and urban wastewater samples reduce the preconcentration efficiency in both sorbents, especially for the Bond Elut C₁₈. The use of the Oasis MAX allowed detection limits between 2.9-25.6, 2.5-12.4 and 2.2-12.7 μg L⁻¹, when processing 250 mL of industrial, influent and effluent sewage treatment plant (STP) samples. Recoveries ranged between 46-91, 28-91 and 39-114% (industrial, influent and effluent STP, respectively) for samples spiked with all the antibiotics at 25 and 75 μg L⁻¹ (n = 3 for each level).     

Emission to air of volatile organotins from tributyltin‐contaminated harbour sediments

An analytical method for determining the presence in air of volatile forms (e.g. chlorides) of tributyltin (TBT) and that of methylbutyltins Me _nBu_(4?n)Sn (n = 1–3) was developed and used to establish whether dredged harbour sediments contaminated with TBT served as sources of air pollution with respect to organotin compounds. The method was based on active sampling of the air being analysed and sorption of analytes onto Poropak‐N. Sorbed methylbutyltins were extracted with dichloromethane and analysed by gas chromatography using flame photometric detection. Other butyltins were converted into butyltin hydrides prior to analysis by gas chromatography. It was shown that TBT‐contaminated sediments from Marsamxett Harbour, Malta, placed in 0.5 l chambers through which air was displaced by continuous pumping for 11 days released mainly methylbutyltins, with concentrations (as tin) reaching maximum 48 h mean values of 8.7 (Me₃BuSn), 22.1 (Me₂Bu₂Sn) and 93.0 ng m^?3(MeBu₃Sn) being measured. Other volatile forms of TBT, dibutyltin and monobutyltin were detected in the headspace air, but very infrequently and at much lower tin concentrations (<2 ng m^?3). It was also shown that methylbutyltins dissolved in sea‐water ([Sn] = 0.2 to 400 ng l^?1) were very difficult to exsolve from this medium, even on prolonged evaporation of the solutions using mechanical agitation and active ventilation. The results suggest that emission of methylbutyltins from contaminated sediments probably occurs only from the surface of the material. The environmental implications of these findings in the management of TBT‐polluted harbour sediments are discussed. Copyright © 2002 John Wiley & Sons, Ltd.     

Determination of Organotin Compounds in Wine by Microwave-Assisted Extraction and High Performance Liquid Chromatography–Inductively Coupled Plasma Mass Spectrometry

A new analytical procedure for the determination of five organotin compounds in several matrix wine samples is reported. The organotin compounds were extracted by microwave-assisted extraction with n-hexane. Extraction conditions, such as volume of n-hexane required, extraction temperature, and extraction time, were investigated and optimized by an orthogonal array experimental design. The determination of organotin compounds in the final extracts was carried out by liquid chromatography–inductively coupled plasma mass spectrometry. The procedure showed limits of detection between 0.029–0.049 µg · L^?1. The linearity was in the range of 0.5 to 100 µg · L^?1. The precision expressed as relative standard deviation (RSD) was below 9.43%. The developed method was successfully employed to analyze different matrix wine samples, and some analytes were detected at the level of 0.053 to 1.14 µg · L^?1.     

Determination of pesticides originating from golf courses by solid-phase extraction and liquid chromatography-tandem mass spectrometry

A multi-residue method using liquid chromatography coupled to triple quadrupole tandem mass spectrometry (LC-MS/MS), associated with solid-phase extraction (SPE), was developed for the determination of 21 pesticides in water samples. The compounds investigated are used for the maintenance of golf courses and ordinarily measured by gas chromatography-mass spectrometry (GC-MS). Electrospray ionisation (ESI) was applied to all compounds, and LC and MS conditions were optimised to measure them under SRM mode. This method showed excellent linearity ranges for all pesticides, with correlation coefficients greater than 0.996. Two kinds of extraction cartridges, namely, styrene divinylbenzene polymer (Sep-Pak PS-2) and divinylbenzene-N-vinylpyrrolidone copolymer (Oasis HLB), were tested and the extraction conditions were optimised. All the pesticides were determined using acetonitrile and ethyl acetate as eluents in both cartridges, and good recoveries (>77%) and repeatability with low relative standard deviations (RSDs, <12%) were achieved from ultra-pure water. In addition, satisfactory recoveries (>76%) and low intra-day and inter-day RSDs (<15%) of all pesticides were also obtained with the Sep-Pak PS-2 cartridge when using river water. The method limits of detection (LODs) ranged between 0.068 (diazinon) and 3.9 (triclopyrbutoxyethyl)?ng?L^?1. The analytical method was successfully applied for the determination of pesticides in surface river water.     

Antioxidative properties of defatted dabai pulp and peel prepared by solid phase extraction

Solid phase extraction (SPE) using Sep-Pak^? cartridges is one of the techniques used for fractionation of antioxidant compounds in waste of dabai oil extraction (defatted dabai parts). The aim of this study was to determine the phenolic compounds and antioxidant capacity in crude extracts and several SPE fractions from methanolic extract of defatted dabai pulp and peel. Based on SPE, Sep-Pak^? cyanopropyl and C₁₈ cartridges were used to fractionate the antioxidant-rich crude extracts into water and methanolic fractions. Analyzed using LC-MS, flavonoids, anthocyanins, saponin derivatives and other unknown antioxidative compounds were detected in the defatted dabai crude extracts and their SPE fractions. Anthocyanins were the major phenolic compounds identified in the defatted dabai peel and detected in most of the SPE fractions. Methanolic fractions of defatted dabai parts embraced higher total phenolics and antioxidant capacity than water fractions. This finding also revealed the crude extracts of defatted dabai peel have the most significant antioxidant properties compared to the methanolic and water fractions studied. The crude extract of defatted dabai parts remain as the most potent antioxidant as it contains mixture of flavonoids, anthocyanins and other potential antioxidants.     

Synthesis and spectroscopic characterization of new organotin(IV) complexes with bis(3,5-dimethylpyrazol-1-yl)dithioacetate

New organotin(IV) derivatives containing the anionic ligand bis(3,5-dimethylpyrazolyl)dithioacetate [L₂CS₂]^? have been synthesized by reaction of SnR _n X_{4? n} (R?=?Me, Ph, ⁿ Bu or Cy; n?=?1–3) acceptors and Li[L₂CS₂]. Mononuclear complexes of the type [L₂CS₂]R _n SnCl_{4? n ?1}} have been obtained and fully characterized by elemental analyses and FT-IR in the solid state, and by NMR (¹H and ¹¹⁹Sn) spectroscopy, conductivity measurements and electrospray ionization mass spectrometry (ESI-MS) in solution. ESI-MS spectra of methanol solutions of diorganotin derivatives, recorded with fragmentor potentials of 0, 50, 100 and 150?V, show the occurrence at 150?V of peaks attributable to the loss of the CS₂ group from the ligands and the formation of stable tetraorganodistannoxane species.     

Solid phase extraction of trace amounts of silver (I) using dithizone-immobilized alumina-coated magnetite nanoparticles prior to determination by flame atomic absorption spectrometry

A new, simple, fast and reliable solid-phase extraction (SPE) method has been developed to separation/preconcentration of trace amounts of silver ion from environmental water samples using dithizone/sodium dodecyl sulfate immobilized on alumina-coated magnetite nanoparticles (DTZ/SDS-ACMNPs) and its determination by flame atomic absorption spectrometry. The coating of alumina on Fe₃O₄ NPs not only avoids the dissolving of Fe₃O₄ NPs in acidic solution, but also extends their application without sacrificing their unique magnetization characteristics. This method avoided the time-consuming column-passing process of loading large volume samples in traditional SPE through the rapid isolation of DTZ/SDS-ACMNPs with an adscititious magnet. Optimal experimental conditions including amount of DTZ/SDS, pH value, standing time, sample volume, type, volume and concentration of eluent and co-existing ions have been studied and established. Under the optimal experimental conditions, the detection limit for Ag(I) with enrichment factors of 100 was found to be 0.52?ng?mL^?1 and its relative standard deviations (RSD) was 3.4% (n?=?10, C?=?5.0?µg?mL^?1). The linear range of calibration curve for Ag(I) was 2–5000?ng?mL^?1 with a correlation coefficient of 0.9991. The proposed method was successfully applied to the determination of target analyte in different water and wastewater samples. The validity of the method has been checked by applying it to study the recovery of silver ion in spiked water and wastewater samples.     

Solid-phase Extraction for Analysis of Short-Chain Chlorinated Paraffins in Water Samples

A method for analysis of short-chain chlorinated paraffins (SCCPs) in water based on solid-phase extraction (SPE) was established using electron capture negative chemical ionization mass spectrometry (GC-ENCI-MS). The SPE parameters, including the sorbent, eluent and elution volume were optimized. The Agilent Bond Elut-C₁₈ was precleaned with 3 mL of hexane and 3 mL of methanol, and subsequently conditioned with 3 mL H₂O prior to use. After the water samples were enriched by the cartridge, the sample was washed with 3 mL of 10% (V/V) methanol and eluted with 3 mL of hexane-dichloromethane (1:1, V/V) solution. The results indicated that the limits of detection (LOD) for SCCPs were 18 ng L^?1, while the corresponding limits of quantitation (LOQ) were 60 ng L^?1. The spiked recovery range was 90%–135%, with a relative standard deviation of less than 10%. Finally, 20 surficial water samples around Beijing were collected and SCCPs contents were analyzed using the proposed method. The SCCPs concentrations ranged from less than LOD to 682 ng L^?1 with a mean concentration of 216 ng L^?1.