Analysis 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.

Single Photon Ionization/Photoelectron Ionization-Membrane Introduction Mass Spectrometry for On-line Analysis Ethers Gasoline Additive in Water

A magnetic field enhanced photoelectron ionization (MEPEI) source combined with single photon ionization (SPI) for membrane inlet time-of-flight mass spectrometry was used for on-line detection of ether gasoline additive. Methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), methyl tert-amyl ether (TAME) and isopropyl ether (DIPE) were selected as the typical pollutants. A membrane inlet was used to transfer the analytes from liquid into gas phase in an on-line manner by pervaporization without sample pretreatment. Less sample fragments were in SPI, and molecular ions could be used to quick preliminarily qualitative analysis; high energy electrons and fragmentations produced by MEPEI can be used to accurate qualitative isomers and overcame the problem of resolution of overlapping peaks in complex matrix when using direct injection. Under the optimal conditions such as membrane temperature 60 degrees C, membrane thicknesses 50 mu m and membrane areas 160 cm(2), the single sample analysis time was less than 100 s, and the limits of detection for MTBE, ETBE, TAME and DIPE were 5.5, 4.8, 3.3 and 4.3 mu g/L, respectively. The instrument has been successfully applied to rapid analysis of MTBE in simulated water by gasoline.

Stable carbon and hydrogen isotope analysis of methyl tert-butyl ether and tert-amyl methyl ether by purge and trap-gas chromatography-isotope ratio mass spectrometry: Method evaluation and application

In order to monitor the behaviour of contaminants in the aqueous environment effective enrichment techniques often have to be employed due to their low concentrations. In this work a robust and sensitive purge and trap-gas chromatography-isotope ratio mass spectrometry method for carbon and hydrogen isotope analysis of fuel oxygenates in water is presented. The method evaluation included the determination of method detection limits, accuracy and reproducibility of deltaD and delta(13)C values. Lowest concentrations at which reliable delta(13)C values could be determined were 5 microg L(-1) and 28 microg L(-1) for TAME and MTBE, respectively. Stable deltaD values for MTBE and TAME could be achieved for concentrations as low as 25 and 50 microg L(-1). Good long-term reproducibility of delta(13)C and deltaD values was obtained for all target compounds. But deltaD values varying more than 5 per thousand were observed using different thermal conversion tubes. Thus, a correction of deltaD values in the analysis of groundwater samples was necessary to guarantee comparability of the results. The applicability of this method was shown by the analysis of groundwater samples from a gasoline contaminated site. By two dimensional isotope analysis two locations within this site were identified at which anaerobic and aerobic degradation of methyl tert-butyl ether occurred.

Compound-Specific Stable Carbon Isotope Analysis of MTBE in Groundwater Contamination Fingerprinting Studies: The Use of Hydrogeologic Principles to Assess Its Validity

Methyl-tert-butyl ether (MTBE) is an oxygenate added to gasoline in the United States and elsewhere to boost the octane ratio and reduce tailpipe emissions. Because of its known usage time frame, the presence of MTBE can help estimate the age of gasoline releases to the environment. However, because of its ubiquity, its presence can no longer be used to fingerprint, or differentiate, gasoline plumes in groundwater. Compound-specific stable carbon isotope analysis has recently become a method for differentiating MTBE sources and plumes affecting groundwater. In the present study, groundwater samples were collected from 20 monitoring wells located at two gasoline service stations in central New Jersey in an attempt to differentiate the dissolved gasoline plumes and possibly identify their sources. The carbon isotope ratio (13C/12C expressed as δ13C) values for each sample were determined through gas chromatography–isotope ratio–mass spectrometry (GCIRMS), and the impacted area for each plume was delineated. As biological degradation of MTBE proceeds, δ13C becomes heavier; petroleum-degrading bacteria preferentially assimilate the lighter 12C isotope, thereby enriching the residual MTBE in the heavier 13C isotope. The isotopic composition of MTBE at different locations demonstrated the varying degree to which MTBE had been altered by biodegradation. The δ13C values can also provide insight into the type of release and the magnitude of biodegradation. Two types of leaks occurred at the sites: a shallow piping leak and deeper leak from a tank system. δ13C values in the vicinity of the shallow leak were heavier, revealing increased biodegradation in the soil, while δ13C values in the vicinity of the tank leak were lighter, revealing the lack of biological degradation in non-aqueous phase liquid (NAPL) trapped beneath the water table. An assessment is provided where the physical site characteristics responsible for petroleum weathering are considered in comparison with the measured δ13C values.

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.

Trace analysis of methyl tert-butyl ether in water samples using headspace solvent microextraction and gas chromatography–flame ionization detection

In this study, a simple, rapid and efficient method for the extraction and determination of MTBE in water samples by the headspace solvent microextraction (HSME) and gas chromatography at sub (μg/l) level is described. Some significant variables such as type of solvent, extraction time, salt concentration, sample and microdrop volumes, stirring rate, sample and microsyringe needle temperatures were optimized. Using optimum extraction conditions (benzyl alcohol as extracting solvent, 4 M NaCl, sample temperature 35 °C, sample volume 6 ml, stirring rate 1000 rpm, microsyring needle temperature −6 °C, extraction time 7.5 min and micro drop volume of 2 μl) a detection limit of 0.06 μg/l and a good linearity ( R 2 > 0.999) in a calibration range of 0.1–500 μg/l were achieved. This HSME method was applied to the analysis of MTBE in tap, well and spring waters and a groundwater sample contaminated by leaking gasoline from an underground storage tank (LUST) in a gasoline service station.

Analysis of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) in ground and surface water

The fuel oxygenate methyl tert-butyl ether (MTBE) is one of the most frequently detected volatile organic compounds in groundwater and, thus, has become a priority groundwater pollutant over the last decade. Methods for the quantitative determination and for compound-specific isotope analysis (CSIA) of MTBE and its key degradation intermediate, tert-butyl alcohol (TBA), in ground and surface water are reviewed. These compounds are exclusively analyzed by gas chromatography (GC), mainly with mass spectrometric (MS) detection because of the requirements for selectivity and sensitivity. Sample introduction/enrichment based on direct aqueous injection, headspace analysis, solid-phase microextraction (direct immersion and headspace), and purge-and-trap is discussed. Specific advantages and disadvantages of these techniques are compared and criteria are given for choosing an appropriate method. Furthermore, it is shown that CSIA can be used to determine the isotopic composition of MTBE and related compounds in the low μg/L range and will therefore become an invaluable tool in the characterization of the environmental fate of such pollutants.

Analysis of methyl tert-butyl ether in the atmosphere and implications as an exclusive indicator of automobile exhaust

This study investigated the feasibility of using methyl tert-butyl ether (MTBE) as an unambiguous indicator for traffic emissions. The concept involves using ratios of volatile organic compounds (VOCs) to MTBE concentrations, which are characteristic of traffic emissions to reveal the excess concentration contributed by non-traffic sources. To execute this concept an analytical method based on gas chromatography/mass spectrometry was employed to measure various VOCs and MTBE simultaneously. Poor separation of MTBE and 2-methyl pentane caused by water in the samples was circumvented by selectively monitoring the characteristic ion peak (m/z=73) of MTBE. Air samples were collected during three periods and analyzed simultaneously for MTBE and other ozone precursors so that their ratios to MTBE could be examined. Two sample collections at different locations were made in an urban environment, in which high correlation in concentration was observed between most VOCs and MTBE for samples collected during hours of heavy traffic. The third collection was made near a cluster of petroleum refineries in order to compare VOCs/MTBE ratios from different VOC source regions. Ratios of ethene/MTBE, benzene/MTBE, toluene/MTBE, etc. obtained from the industrial site were significantly greater than those from the two roadside sites indicative of additional VOC sources other than internal combustion. Although rather constant values of VOCs/MTBE ratios were observed for most urban samples, the ratios noticeably shifted toward higher values in late night samples when the sources from traffic subsided and the effect of sinks prevailed.

Improved Analysis of MTBE, TAME, and TBA in Petroleum Fuel-Contaminated Groundwater by SPME Using Deuterated Internal Standards with GC−MS

An improved method is described for the routine analysis of methyl tert-butyl ether (MTBE), tert-amyl methyl ether (TAME), and tert-butyl alcohol (TBA) in petroleum fuel-contaminated groundwater samples using solid-phase microextraction (SPME) and deuterated internal standards combined with gas chromatography mass spectrometry (GC-MS). Factors affecting method performance (SPME fiber selection, headspace or liquid extraction, extraction time, calibration conditions, salt addition, method sensitivity, and matrix effects) are evaluated using groundwater samples from a chalk aquifer contaminated with petroleum fuel containing MTBE, TAME, and TBA. The detection sensitivity and analytical efficiency of the method was optimized for these compounds using a PDMS-Carboxen fiber, sample NaCl content of 25% (w/v), and extraction time of 30 min. Internal calibration standards (deuterated MTBE and TBA) are necessary to control extraction errors during analysis. SPME extraction efficiency and detection sensitivity for ...

A rapid and sensitive method for methyl tert-butyl ether analysis in water samples by use of solid phase microextraction and gas chromatography–mass spectrometry

This work describes a rapid and sensitive solid-phase microextraction (SPME) method for the isolation and analysis of methyl tert-butyl ether in water samples. Methyl tert-butyl ether was extracted from aqueous solutions using SPME fibre coated with Divinylbenzene/Carboxen™/polydimethylsiloxane (30 μm film thickness) and analysed by GC–MS with a Hewlett Packard 6890/5973 system equipped with a capillary column coated with Vocol™ (30 m×0.25 mm,1.5 μm film thickness). Extraction parameters and chromatographic separation conditions were optimised. The developed method showed good analytical performance in terms of precision (RSD between 2% and 8%) and accuracy (mean recovery from 96% to 104%) with a detection limit of 14 ppt. Finally the method was applied to surface, tap and commercial mineral water samples, as well as snow samples collected along a busy road of Bologna town area. The median concentration of methyl tert-butyl ether in all these samples (0.05–0.4 ppb) was well below the maximum aqueous contamination levels in water adopted in the United States (13 ppb).

Accurate Chemical Analysis of MTBE in Environmental MediaTechnical Note

The new millennium ushers in changes for refiners of automobile gasoline in the United States, as well as for the state and federal regulators who establish guidelines for gasoline formulation and environmental regulation governing the fate of gasoline-related chemicals in the nation's air, soil and groundwater. One current issue in the gasoline formulation debate centers on the comparison of the proven benefits of the addition of chemical oxygenates--especially methyl tert -butyl ether (MTBE)--to gasoline (to improve tailpipe emission quality) against the presumed environmental problems caused by the presence of oxygenates in ground- and surface waters due to fugitive releases of gasoline. Credible debate on this subject presumes that current and past environmental monitoring data for MTBE in environmental samples is accurate and precise. Experience suggests that this assumption is not correct, in part because certain analytical methodologies--particularly older methods supported by the U.S. Environmental Protection Agency--can fall short of reasonable data quality goals for measurement of MTBE. This Technical Note summarizes the standard EPA methods available to site investigators who need to measure MTBE in environmental media, the limitations and advantages of these measurement techniques, and recommendations for improving these standard EPA methods to yield the highest quality MTBE environmental residue data.

Cost–benefit analysis of methyl tert-butyl ether and alternative gasoline formulations

This paper presents a cost–benefit analysis of the 1990 Clean Air Act Amendments (CAAA) requiring the addition of oxygen content in gasoline, using California as a case study. The valuation and comparison of costs and benefits for several fuel blends (with and without oxygen content) provides a framework to investigate cross-media (air, water, soil) tradeoffs. We use known valuation methods such as the travel cost method to derive recreational value, the averting expenditures approach and cost of illness approach to derive public health costs, and market price method to quantify increases in fuel price and fuel efficiency costs in order to compare the alternatives. We use data from California to evaluate the current fuel blend with methyl tert-butyl ether (MTBE), a fuel blend with ethanol (ethyl alcohol), and a fuel blend without oxygenated compounds. The most expensive option to meet the 1990 CAAA is the current reformulated gasoline blend with MTBE, which results in a net cost to California's economy of between $0.9 and 2.7 billion dollars annually. The cost of treating groundwater contaminated with MTBE is a major cost factor. Our assessment indicates that the non-oxygenated gasoline formulation is the most cost-effective, particularly in the long-term, once refiners are able to implement modifications to their installations or negotiate long-term supply contracts for these additives. Several strategies are identified to transition out of using the current gasoline blend with MTBE.

Second-order chemometric standardization for high-speed hyphenated gas chromatography: Analysis of GC/MS and comprehensive GC�GC data

Second-order data such as those provided by hyphenated instruments like gas chromatography with mass spectrometry detection (GC/MS) provide a wealth of information. Multichannel detection combined with multivariate analysis allows compounds that have been incompletely resolved by chromatography to be accurately quantitated. Because of this ability, chromatographic instruments can be operated in a significantly faster, reduced resolution mode. One reason this practice has not become common is that retention time variations complicate comparison of multiple data sets. In this article, an objective retention time standardization technique is presented that substantially improves quantitation. This work demonstrates a key advantage of second-order chemical analysis—that is, the ability to correct for retention time variation found in data from GC/MS analyzers and a relatively new hyphenated gas chromatographic analyzer known as high-speed comprehensive two-dimensional gas chromatography (comprehensive GC×GC). Second-order chromatographic standardization is demonstrated for the GC/MS analysis of methyltert-butyl ether (MTBE) in gasoline. The selectivity of capillary gas chromatography and mass spectrometry, combined with second-order analysis, allows this analysis to be performed in 40 s. Generalized rank annihilation method (GRAM) is used to quantify MTBE. Without standardization, an average retention time variation of 1.3% between standards and samples led to a quantitative precision error of about 20%. Second-order chromatographic standardization reduced this error to <5%. The standardization technique was also tested on comprehensive GC×GC data. In comprehensive GC×GC, the second of two columns repeatedly performed subsecond separations on portions of the effluent from a first column of different chemical selectivity. Comprehensive GC×GC of a white gas mixture modified with several test aromatic compounds was performed. The standardization demonstrated that retention times in comprehensive GC×GC are very repeatable in short column runs. GRAM was used to quantify overlapped ethylbenzene and p-xylene peaks in comprehensive GC×GC data. Because GRAM can be successfully applied to comprehensive GC×GC data, full resolution of all the analytes of interest is not necessary. As a result, comprehensive GC×GC run times can be dramatically shortened, which has significant implications for analyses in which short cycle times are of paramount importance. ©1999 John Wiley & Sons, Inc. J Micro Sep 11: 97–107, 1999

A New GC-MS Experiment for the Undergraduate Instrumental Analysis Laboratory in Environmental Chemistry: Methyl-t-butyl Ether and Benzene in Gasoline

With the recent ACS approval of an option in environmental chemistry at the undergraduate level, there is a need for new experiments that illustrate fundamental principles of instrumental analysis in the context of environmental chemistry. We describe an experiment that utilizes combined gas chromatography-mass spectrometry (GC-MS) in the qualitative and quantitative analysis of methyl tert-butyl ether (MTBE) and benzene in gasoline. This is particularly appropriate, given the increased use of oxygenates in reformulated gasolines in the United States. In addition to illustrating the fundamentals of GC and MS, this experiment demonstrates (i) the use of internal standards to improve precision; (ii) the application of the method of standard additions; and (iii) the importance of techniques such as selected ion extraction/monitoring in the identification and measurement of specific highly volatile organic compounds in complex environmental mixtures.