Determination Of Methyl Tert-butyl Ether Research Articles

Use of Ionic Liquids for Trace Analysis of Methyl Tert-Butyl Ether in Water Samples using in situ Solvent Formation Microextraction Technique and Determination by GC/FID

A simple and efficient method for the determination of methyl tert-butyl ether (MTBE) in water samples is presented. The analytical method is based on use of 1-octyl-3-Methyl-imidazolium chloride [OMIM][Cl] and sodium hexafluorophosphate (NaPF6) as an extractant solvent ([OMIM][PF6] is established and finally MTBE separated/preconcentrated by an in situ solvent formation microextraction (ISFME) technique. Later on, the extractant containing the analyte is recovered by centrifugation and thermally desorbed. The analyte is finally determined by gas chromatography/flame ionization detection (ISFME-GC/FID). The main variables involved in the extraction and thermal desorption steps have been studied in depth. Once evaluated, the analytical method has been characterized in terms of linearity, sensitivity, precision, and accuracy. The limit of detection was 0.09 μg L−1 while the precision, expressed as relative standard deviation, was 1.9% (n = 7). In addition, acceptable recovery values were obtained in samples of different sample including lake, rain, tap, and well water samples.

Simultaneous Determination of MTBE and BTEX in the Groundwater of Gas Station by Head-Space-GC

The content of characteristic pollutants including methyl tert-butyl ether (MTBE) and benzene, toluene, ethyl benzene, p-xylene, m-xylene and o-xylene (BTEX) were determined by head-space-GC. A HP-FFAP capillary column was used in this method. In the mass concentration range of 14.8μg·L-1~1760μg·L-1, there were good linearity relationships between the GC peak areas and the mass concentrations of components with correlation coefficient above 0.999.The detection limits were in the rage of 2.0μg·L-1~2.3μg·L-1. Tests for recoveries and precision were made by standard addition method, values of recoveries and RSDs (n=6) found were in the range of 95%~105% and 0.8%~5.5%.

Ionic-liquid-mediated poly(dimethylsiloxane)- grafted carbon nanotube fiber prepared by the sol-gel technique for the head space solid-phase microextraction of methyl tert -butyl ether using GC

A headspace solid-phase microextraction method was developed for the preconcentration and extraction of methyl tert-butyl ether. An ionic-liquid-mediated multiwalled carbon nanotube-poly(dimethylsiloxane) hybrid coating, which was prepared by covalent functionalization of multiwalled carbon nanotubes with hydroxyl-terminated poly(dimethylsiloxane) using the sol-gel technique, was used as solid-phase microextraction adsorbent. This innovative fiber exhibited a highly porous surface structure, high thermal stability (at least 320°C) and long lifespan (over 210 uses). Potential factors affecting the extraction efficiency were optimized. Under the optimum conditions, the method LOD (S/N = 3) was 0.007 ng/mL and the LOQ (S/N = 10) was 0.03 ng/mL. The calibration curve was linear in the range of 0.03-200 ng/mL. The RSDs for one fiber (repeatability, n = 5) at three different concentrations (0.05, 1, and 150 ng/mL) were 5.1, 4.2, and 4.6% and for the fibers obtained from different batches (reproducibility, n = 3) were 6.5, 5.9, and 6.3%, respectively. The developed method was successfully applied to the determination of methyl tert-butyl ether in different real water samples on three consecutive days. The relative recoveries for the spiked samples with 0.05, 1, and 150 ng/mL were between 94-104%.

Two-Dimensional Cataluminescence Sensor Based on Nano-SnO<SUB>2</SUB> Materials for Determination of Methyl Tert-Butyl Ether

Two-Dimensional Cataluminescence Sensor Based on Nano-SnO<SUB>2</SUB> Materials for Determination of Methyl Tert-Butyl Ether

Headspace solid-phase microextraction using poly(ethylene glycol) grafted multi-walled carbon nanotube fibers for the determination of methyl tert-butyl ether in water samples

A simple, sensitive, and accurate method for the determination of methyl tert-butyl ether (MTBE) in water samples has been developed based on headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-flame ionization detection (GC-FID). A sol–gel based coating fiber using poly(ethylene glycol) (PEG) grafted onto multi-walled carbon nanotubes (PEG-g-MWCNTs) as the extraction phase was prepared and used for the extraction of MTBE. The relative standard deviations (RSDs) for one fiber (repeatability) (n = 6) and between fibers or batch to batch (reproducibility) (n = 3) were obtained. The repeatability was assessed at low (0.1 ng mL−1) and high (100 ng mL−1) concentrations and the RSDs obtained were 5.3 and 4.1%, respectively. The reproducibility obtained for a concentration of 0.1 ng mL−1 was 6.5%. The calibration curve of MTBE was linear in the range from 0.07 to 500 ng mL−1. The limits of detection (S/N = 3) of 0.01 ng mL−1 and the limits of quantification (S/N = 10) of 0.07 ng mL−1 were obtained. The developed method was applied successfully to determine trace level of MTBE in real water samples. The relative recoveries for the spiked samples with 5 ng mL−1 of MTBE were ranged from 91 to 112% and the relative standard deviations were less than 7.8%.

Optimization of dispersive liquid–liquid microextraction and improvement of detection limit of methyl tert-butyl ether in water with the aid of chemometrics

Dispersive liquid–liquid microextraction (DLLME) coupled with gas chromatography–mass spectrometry-selective ion monitoring (GC–MS-SIM) was applied to the determination of methyl tert-butyl ether (MTBE) in water samples. The effect of main parameters affecting the extraction efficiency was studied simultaneously. From selected parameters, volume of extraction solvent, volume of dispersive solvent, and salt concentration were optimized by means of experimental design. The statistical parameters of the derived model were R 2 = 0.9987 and F = 17.83. The optimal conditions were 42.0 μL for extraction solvent, 0.30 mL for disperser solvent and 5% (w/v) for sodium chloride. The calibration linear range was 0.001–370 μg L −1. The improved detection limit with the aid of chemometrics was 0.3 ng L −1. The relative standard deviation (RSD) with n = 9 for 0.1 mg L −1 MTBE in water with and without internal standard was 2.7% and 3.1%, respectively. Under the optimal conditions, the relative recoveries of spiked MTBE in different water samples were in the range of 100–105%.

Capability of headspace based sample preparation methods for the determination of methyl tert-butyl ether and benzene in reed ( phragmites australis) from constructed wetlands

In order to investigate the fate of volatile pollutants such as methyl tert-butyl ether (MTBE) and benzene during the treatment of contaminated water using constructed wetlands, appropriate analytical methods for the analysis of wetland marsh plants, in our case common reed ( Phragmites australis), are required. Different sampling procedures and different headspace (HS) based sample preparation techniques were examined to select and establish the most suited procedure for determining the target analytes in plant material. Static HS, dynamic HS and HS solid phase microextraction (SPME) in combination with GC–MS were optimized and evaluated regarding the extraction yields and their capability for quantitative analysis. Only dynamic HS analysis at 80 °C for 45 min with trapping the analytes on Tenax TA/Chromosorb-106 desorption tubes and the subsequent thermodesorption GC–MS permits the quantitative analysis of MTBE and benzene in reed in a concentration range from 4 ng up to 4 μg per sample weight (approximately 1 g). Static HS and HS SPME analyses were found to be less reliable due to the lack of suitable reference materials. Therefore, these methods do not permit the accurate quantification of pollutant content. Additionally, the HS SPME method is characterized by a restricted linear range of calibration curves. The optimized dynamic HS method was successfully applied for the quantitative analysis of MTBE and benzene within the plants. Their distribution within the plant depending on its height shows a different behavior due to differences in degradability of both substances. While a strong decrease of the concentration of benzene with increasing height of plant was found, the decrease of the concentration of MTBE was not as obvious as observed for benzene. Furthermore, the assessment of plant uptake during phytoremediation was demonstrated by analyzing complete plants for the constructed wetlands investigated.

Headspace-solid-phase microextraction using a dodecylsulfate-doped polypyrrole film coupled to ion mobility spectrometry for analysis methyl tert-butyl ether in water and gasoline

A simple and sensitive method for the determination of methyl tert-butyl ether (MTBE) in water using headspace-solid-phase microextraction (HS-SPME) at sub-ng mL −1 concentrations is described. The analysis was carried out using a cooled SPME fiber coated with a film of dodecylsulfate-doped polypyrrole coupled to ion mobility spectrometry equipped with corona discharge ionization. The headspace-solid-phase microextraction experimental procedures to extract MTBE in water samples were optimized with a dodecylsulfate-doped polypyrrole coated fiber at a 30 min extraction time, extraction temperature of 40 °C, sodium chloride concentration of 2.5 mol L −1 and desorption temperature of 140 °C. Two linear calibration curves respectively in the ranges of 2–17 ng mL −1 and 10–70 ng mL −1 with detection limits of 0.7 ng mL −1 and 4.9 ng mL −1 were obtained. Relative standard deviations for three replicates in water samples were <10%. The capability of dodecylsulfate-doped polypyrrole to extract MTBE has been compared with the results obtained based on the literature data for commercial fiber. The results shows that dodecylsulfate-doped polypyrrole, as a solid-phase microextraction fiber coating, is suitable for successful extraction of MTBE having detection limits comparable to what obtained with commercial fibers. Finally, the proposed method was applied to the analysis of MTBE in three ground water samples and regular unleaded gasoline from petrol station in Tehran central district, Iran.

A Sensitive Method for Methyl tert-Butyl Ether Analysis in Water Samples by a New HS-SPME Vial and GC

In this study, a new sample vial has been designed for the extraction and determination of methyl tert-butyl ether (MTBE) in water samples by headspace solid-phase microextraction method. The special feature of this new vial is cooling the HS above the aqueous sample by cold water stream for maximum analyte absorption on SPME fiber coating. The analysis was by a gas chromatograph equipped with flame ionization detector and a capillary column (CP-sil 13 CB). Some significant variables affecting the extraction procedure were optimized. By use of divinylbenzene/carboxen/polydimethylsiloxane fiber, a sample volume of 10 mL, stirring rate of 1,000 rpm, salt concentration of 24%, extraction time of 15 min and extraction temperature of 83 °C, detection limit of 0.022 μg L−1 and a good linearity (R2 = 0.998) in a calibration range of 0.1–400 μg L−1 were achieved. The relative standard deviation for triplicate runs ranged between 6 and 8%. The method could be applied to the analysis of trace levels of MTBE in various water samples.

Simultaneous determination of methyl tert-butyl ether, its degradation products and other gasoline additives in soil samples by closed-system purge-and-trap gas chromatography–mass spectrometry

A new protocol for the simultaneous determination of methyl tert-butyl ether (MTBE); its main degradation products: tert-butyl alcohol (TBA) and tert-butyl formate (TBF); other gasoline additives, oxygenate dialkyl ethers: ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME) and diisopropyl ether (DIPE); aromatics: benzene, toluene, ethylbenzene and xylenes (BTEX) and other compounds causing odour events such as dicyclopentadiene (DCPD) and trichloroethylene (TCE) in soils has been developed. On the basis of US Environmental Protection Agency (EPA) method 5035A, a fully automated closed-system purge-and-trap coupled to gas chromatography/mass spectrometry (P&T-GC/MS) was optimised and permitted to detect μg/kg concentrations in solid matrices avoiding losses of volatile compounds during operation processes. Parameters optimised were the sampling procedure, sample preservation and storage, purging temperature, matrix effects and quantification mode. Using 5 g of sample, detection limits were between 0.02 and 1.63 μg/kg and acceptable method precision and accuracy was obtained provided quantification was performed using adequate internal standards. Soil samples should be analysed as soon as possible after collection, stored under −15 °C for not longer than 7 days if degradation products have to be analysed. The non-preservative alternative (empty vial) provided good recoveries of the most analytes when freezing the samples up to 7 day holding time, however, if biologically active soil are analysed the preservation with trisodium phosphate dodecahydrate (Na 3PO 4·12H 2O or TSP) is strongly recommended more than sodium bisulphate (NaHSO 4). The method was finally applied to provide threshold and background levels of several gasoline additives in a point source and in sites not influenced by gasoline spills. The proposed method provides the directions for the future application on real samples in current monitoring programs at gasoline pollution risk sites where till now little monitoring data for MTBE in soils are available.

State of the Art in the Determination of MTBE in Natural Waters and Soils

Methyl tert-buthyl ether (MTBE) is used as an oxygenate additive in gasoline, and in the last years contamination of natural water, soils or air has taken place as result of MTBE use. Furthermore, MTBE is the second most common volatile compound (VOC) detected in a survey of shallow urban aquifers. This review focuses on the most critical steps, for sample preparation methodologies from an analytical point of view. Several enrichment and injection techniques are discussed, including direct injection, headspace analysis, purge and trap and solid-phase microextraction. The methods for the determination of methyl tert-butyl ether (MTBE) in environmental samples have been rapidly developed during last decade. Also, the current status of the analytical methods used in the determination of MTBE in water and soil is reviewed including the compound-specific stable isotope analysis (CSIA), which is an important tool in environmental sciences and allows the allocation of contaminant sources.

Continuous on-line determination of methyl tert-butyl ether in water samples using ion mobility spectrometry

A rapid analytical procedure for the on-line determination of methyl tert-butyl ether (MTBE) in water samples was developed. A new membrane extraction unit was used to extract the MTBE from water samples. The concentration of MTBE was determined using ion mobility spectrometry with 63Ni ionization and corona discharge ionization without chromatographic separation. Both ionization methods permit the sensitive determination of MTBE. A detection limit of 100 μg/L was established for the on-line procedure. Neither the inorganic compounds, humic substances nor gasoline were found to exert a significant influence on the peak intensity of the MTBE. The screening procedure can be used for concentrations of monoaromatic compounds (benzene, toluene, xylene) up to 600 μg/L. No sample preparation is required and the analysis results are available within 5 min. In order to determine concentrations between 10 μg/L and 100 μg/L, a discontinuous procedure was developed on the basis of the same experimental set-up.

Determination of methyl tert-butyl ether in gasoline: a comparison of three fast methods based on mass spectrometry

A high-speed quantitative analysis of methyl tert-butyl ether (MTBE) using three different methods with mass spectrometry detection has been performed. The first method is based on fast chromatography and required an analysis time of 5.23 min per sample, although a certain period (6 min) was necessary for the initial measurement conditions to be regained prior to analysing the next sample. The other two are non-separative methods and are based on direct injection and headspace generation. The analysis times were 1.5 and 3.5 min, respectively, although in the latter case an additional period of time was required to extract volatiles from the sample. The analytical characteristics of all three methods are highly satisfactory in terms of linearity, lack of fit, precision and accuracy. The methods were applied to the determination of MTBE in different gasoline samples. The non-separative methods afforded slightly higher concentrations than those found when fast chromatography was used; this is due to the presence of other minor components that contribute to the abundance of the ion at m/z 73, characteristic of MTBE. We propose a correction that removes this error very satisfactorily and allows the same results to be obtained with all three methodologies proposed.

Determination of methyl tert-butyl ether in gasoline: a comparison of three fast methods based on mass spectrometry

A high-speed quantitative analysis of methyl tert-butyl ether (MTBE) using three different methods with mass spectrometry detection has been performed. The first method is based on fast chromatography and required an analysis time of 5.23 min per sample, although a certain period (6 min) was necessary for the initial measurement conditions to be regained prior to analysing the next sample. The other two are non-separative methods and are based on direct injection and headspace generation. The analysis times were 1.5 and 3.5 min, respectively, although in the latter case an additional period of time was required to extract volatiles from the sample. The analytical characteristics of all three methods are highly satisfactory in terms of linearity, lack of fit, precision and accuracy. The methods were applied to the determination of MTBE in different gasoline samples. The non-separative methods afforded slightly higher concentrations than those found when fast chromatography was used; this is due to the presence of other minor components that contribute to the abundance of the ion at m/ z 73, characteristic of MTBE. We propose a correction that removes this error very satisfactorily and allows the same results to be obtained with all three methodologies proposed.

Determination of fuel dialkyl ethers and BTEX in water using headspace solid-phase microextraction and gas chromatography–flame ionization detection

A simple procedure for the determination of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), ethyl butyl ether (EBE), tert-amyl methyl ether (TAME), benzene, toluene, ethylbenzene, and xylenes (BTEX) in water using headspace (HS) solid-phase microextraction (HS-SPME) was developed. The analysis was carried out by gas chromatography (GC) equipped with flame ionization detector (FID) and 100% dimethylpolysiloxane fused capillary column. A 2 7–4 Plackett–Burman design for screening and a central composite design (CCD) for optimizing the significant variables were applied. Fiber type, extraction temperature, sodium chloride concentration, and headspace volume were the significant variables. A 65 μm poly(dimethylsiloxane)-divinylbenzene (PDMS-DVB) SPME fiber, 10 °C, 300 g/l, and 20 ml of headspace (in 40 ml vial) were respectively chosen for the best extraction response. An extraction time of 10 min was enough to extract the ethers and BTEX. The relative standard deviation (R.S.D.) for the procedure varied from 2.6 (benzene) to 8.5% (ethylbenzene). The method detection limits (MDLs) found were from 0.02 (toluene, ethylbenzene, and xylenes) to 1.1 μg/l (MTBE). The optimized method was applied to the analysis of the rivers, marinas and fishing harbors surface waters from Gipuzkoa (North Spain). Three sampling were done in 1 year from June 2002 to June 2003. Toluene was the most detected analyte (in 90% of the samples analyzed), with an average concentration of 0.56 μg/l. MTBE was the only dialkyl ether detected (in 15% of the samples) showing two high levels over 400 μg/l that were related to accidental fuel spill.

Reevaluation of headspace solid-phase microextraction and gas chromatography–mass spectrometry for the determination of methyl tert-butyl ether in water samples

A headspace solid-phase microextraction (SPME) and gas chromatography–mass spectrometry (GC–MS) method has been reevaluated for the determination of methyl tert-butyl ether (MTBE) in water. Factors affecting method performance were examined. The internal standard, deuterated MTBE, is necessary because it allows normalization of the calibration since the deuterated MTBE and MTBE experience the same extraction efficiency. The method detection limit was 6.6 ng/l, with a linear range up to 160 μg/l. SPME extraction efficiency and detection sensitivity for MTBE decreased in the presence of gasoline matrix. However, reliable measurement of MTBE was possible in the background matrix concentration of 0.97 mg/l gasoline using deuterated internal standard. Reproducibility was 4.5% at the spiking level of 47 ng/l. The average recoveries of MTBE in spiked fountain water, tap water, and snow at 60 ng/l and in spiked rainwater at 580 ng/l ranged from 101 to 105%. The method was successfully applied to the analysis of trace levels of MTBE in various water samples, including rain and snow samples collected in Albany, NY, USA.

Interlaboratory comparison study for the determination of methyl tert-butyl ether in water.

This is the first publication which describes the evaluation of the analytical performance and state-of-the-art of the determination of methyl tert-butyl ether (MTBE) in water at ng L(-1) concentrations. An interlaboratory comparison study for the determination of MTBE in water was carried out. Twenty-eight laboratories from seven European countries participated in the study. Twenty of those finally transmitted results to the organiser. Italian spring water, containing no detectable amounts of MTBE was fortified to yield two samples with MTBE concentrations of 0.074 +/- 0.004 microg L(-1) and 0.256 +/- 0.010 microg L(-1). The laboratories applied their regular in-house methods to analyse the water samples. Static headspace, Purge & Trap, solid-phase microextraction (SPME) or direct aqueous injection were used as sample preparation techniques. Subsequent separation and detection of MTBE were performed by gas chromatography/mass spectrometry (GC/MS) or gas chromatography/flame ionisation detection (GC/FID). After rejection of outliers, the overall arithmetic mean of laboratory results corresponded to recoveries of 78 +/- 20% (Sample A) and 88 +/- 20% (Sample B) of the reference concentrations. The between laboratory coefficients of variation (CV) were 32% and 31%, respectively. The organisation of the study and quality assurance measures at the organiser's laboratory are described. Moreover, the measurement results of the participants and the analytical methods used for the determination of MTBE are presented and the correlation between selected method parameters and data quality is discussed.

Determination of MTBE in a recreational harbor using solid-phase microextraction

Discovery of the fuel additive methyl tert-butyl ether (MTBE) in groundwater, surface water, and stormwater has prompted studies of its sources, transport and fate. More limited data, however, is available on the extent of contamination of coastal waters, as well as the persistence of MTBE in the marine environment. We apply here the combination of solid phase microextraction and gas chromatography–mass spectrometry to the detection of sub-to-low μg/l concentrations of MTBE in seawater samples. Analysis of samples collected at the Marina del Rey harbor, a shallow recreational harbor near Los Angeles, CA, show MTBE contamination in the low μg/l level. MTBE measurements were made at different depths, from the surface to the bottom, at five sites within the harbor during months showing no measurable precipitation. The highest concentration of MTBE (18 μg/l) was found at the boat launching ramp, and the lowest (0.2 μg/l) near the harbor entrance, approximately 2.3 km from the ramp. The levels of MTBE measured, as well as their variation over the study period, are fully consistent with recreational boating as the primary source of contamination. No evidence for MTBE contamination from the adjacent stormwater control channel was noted.

Separation and determination of methyl tert-butyl ether and its degradation products by a laboratory-constructed micro-cryogenic chromatographic oven.

A laboratory-made micro-cryogenic chromatographic oven was mainly improved in size, which was controlled at 6 x 6 x 2.5 cm. A thermoelectric system was used to cool the capillary column instead of the traditional liquid cryogen. A cold block connected to the cryogenic module was directly solidified at room temperature with thermally conductive adhesive so that the uniformity of transferring heat was greatly improved, and the size of the system was reduced. Moreover, this system was inexpensive and convenient for both operation and control. The newly developed device coupled with headspace solid-phase microextraction (SPME) was successfully applied to the determination of methyl tert-butyl ether (MTBE) and its degradation products. During the analysis procedure, a 65 microm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber was used to extract MTBE and its degradation products. The extraction was controlled at 50 degrees C for 30 min and the NaCl content in the sample was maintained at 35%. The limits of detection (LODs) ranged from 0.006 microg mL(-1) (for MTBE) to 0.206 microg mL(-1) (for methyl acetate) and the relative standard deviations (RSD%) were below 4%. The spiked recoveries for the developed method were evaluated using various water samples as a matrix.

Sensitive method for determination of methyl tert-butyl ether (MTBE) in water by use of headspace-SPME/GC-MS.

A simple and rapid method for the determination of methyl tert-butyl ether (MTBE) in water by headspace-solid-phase microextraction (headspace-SPME) at sub-microg/L concentrations is described. On using a cooled SPME fiber coated with a 75-microm layer of poly(dimethylsiloxane)/carboxene and heating the sample to 35 degrees C, about 4 times more MTBE is extracted compared to SPME extraction with the fiber placed in the water sample. Stable analytical conditions with a detection limit of 10 ng/L are achieved. By use of a sample volume of 4 mL in a 10 mL vial, a sodium chloride content of 10% (w/w), and an extraction time of 30 min, the total time of an analytical cycle was optimized to 39 min. Precise linearity of R2>0.9991 and R2>0.9916 in the calibration range of 20-5000 ng/L and 20-100 ng/L, both in addition to blanks, respectively, and relative standard deviations of 10% (100 ng/L, long-term) and 11% (20 ng/L, short-term) are presented. The recovery is well within the accepted limits of 83-118% at a concentration of 100 ng/L and even close thereto at trace levels of 20 ng/L (96-125%). The data presented for a concentration of 100 ng/L are examined by statistical methods and show results for the T test at the 95% confidence level. Due to the large concentration range covered, the method is well suited for the monitoring of MTBE in the aquatic environment.