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RATIONALE Cleaning up contaminated sites is a goal of the U.S. Environmental Protection Agency (EPA). A simple, high-throughput, inexpensive, selective, and specific screening method for semi-volatile, polar organic contaminants would provide high spatial resolution for monitoring remediation and for documenting successful clean ups in numerous Superfund, Brownfield, and other contaminated sites. METHODS An autosampler/Direct Analysis in Real Time (DART)/time-of-flight (TOF) mass spectrometer, with or without a Vapur® evacuated flange, was used to analyze 0.01–33% levels of aspirin, diphenylamine, and pentachlorophenol mixed with soil. Triplicate water-soaked swabs were manually rotated in wet analyte:soil mixtures, air dried for 2–3 h, and analyzed directly. To minimize carryover, insensitive and sensitive instrumental conditions were used to analyze high and low analyte levels, respectively. Simulated two-dimensional (2D) mapping and remediation threshold experiments were performed to test the utility of DART-TOFMS for possible sampling strategies. RESULTS Analyte levels differing by factors of 10 were discernible. Data were acquired for 30 swabs in 0.9 min and 3 min with helium stream temperatures of 150 °C and 250 °C and swab transport velocities of 1.45 cm/s and 0.5 cm/s, respectively. With the Vapur flange attached, the average relative standard deviations (RSDs) (n = 3) were between 16% and 40% for different analytes and analyte levels. Carryover was greatly reduced by removing the Vapur flange, but higher RSDs and occasional plugging of the cone orifice were observed. CONCLUSIONS A rapid, simple, rugged, and relatively inexpensive, but selective and sufficiently sensitive, semi-quantitative screening method for semi-volatile, polar, organic compounds in soil was demonstrated. The technique would provide the high spatial resolution necessary to find localized areas of high contamination within contaminated sites that might pose a risk to human and ecological health. Published 2012. This article is a US Government work and is in the public domain in the USA.

Methamphetamine (meth) from meth syntheses or habitual meth smoking deposited on household surfaces poses human health hazards. The U.S. State Departments of Health require decontamination of sites where meth was synthesized (meth labs) before they are sold. National Institute for Occupational Safety and Health (NIOSH) methods for meth analysis require wipe sampling, extraction, clean‐up, solvent exchange, derivatization, and/or mass spectral analysis using selected ion monitoring. Rapid and inexpensive analyses could screen for drug‐contamination within structures with greater spatial resolution, provide real‐time analyses during decontamination, and provide thorough documentation of successful clean ups. Herein an autosampler/open‐air ion source time‐of‐flight mass spectrometric technique is described that required only direct sampling using cotton‐swab wipes. Each wipe sample collection required 2min and data acquisition required only 13s per sample. Optimum collision‐induced dissociation voltages, desorption gas temperatures, and wipe sample solvents were determined for 11 drugs. Peaks were observed in analyte‐ion traces for 0.025µg/100cm 2 of meth and seven other drugs. This level is half the detection limit of NIOSH methods and one‐fourth of the lowest U.S. state decontamination limit for meth. Dynamic ranges of 100 in concentration were demonstrated for eight drugs, which is sufficient for a screening technique. The volatilities of 11 drugs deposited on glass were determined. The pick up of the drugs by solvent‐soaked cotton‐swab wipes from glass relative to acrylic latex paint was also compared. Published in 2011 by John Wiley & Sons, Ltd.

Chemicals are dispersed accidentally, deliberately, or by weather-related events. Rapid mapping of contaminant distributions is necessary to assess exposure risks and to plan remediation. Powdered aspirin or caffeine was dispersed across a concrete driveway using the exhaust port of a shop vacuum cleaner. Water-soaked, cotton-swab, wipe samples were collected to map the dispersant distribution. An autosampler/direct analysis in real time (DART [IonSense, Saugus, MA])/time-of-flight mass spectrometer was used to acquire an ion chromatogram for the most abundant ion. A semi-quantitation map for several levels of caffeine was plotted to demonstrate the feasibility of applying this technology to contaminated sites.

A wipe sample transport was designed and built to meet two objectives: to simplify collection, storage, and transport of cotton swab wipe samples and to provide a sample train of 72 wipe samples nearly ready for analysis when the swabs reach the laboratory. The cotton swabs are mounted on an Al rod that is the sample support for an autosampler used to perform direct analysis in real time (DART 1 )/orthogonal acceleration, time-of-flight mass spectrometry (oa-TOFMS) analyses. The goal is for one analyst to analyze 1000 wipe samples mounted on 14 Al rods in one 8-h shift. 1DART is a registered trademark of JEOL USA, Inc.

Rapid analysis of hundreds of wipe samples after a chemical dispersion event is essential for quickly characterizing the hazard posed to the public. An autosampler was built to pull 76 cotton swabs mounted along a 91-cm (3-foot) long, square aluminum rod in open air, through the ionizing beam of a direct analysis in real time (DART 1 ) ion source interfaced to a time-of-flight mass spectrometer. The rod and swabs mounted on N-scale model railroad flat cars were pulled through the ion source in 7.5 min by a 7-rpm motor. Percent relative standard deviations (%RSDs) of 18.5% to 21.3% were obtained for the chromatographic peak areas of the protonated molecule. Maximum-to-minimum ratios of the areas were between 2.22 and 2.71. Measured exact masses of analyte ions were always accurate to within 1 mDa. 1DART is a registered trademark of JEOL USA, Inc, Peabody, MA.

Identification of compounds in contaminated media is essential for determining sources of pollution and for assessing risks posed by the chemicals to ecosystems or human health. Eighty-five compounds were identified or tentatively identified in a 1-L extract of water sampled above a pollutant plume containing wastes from a chemical plant. Gas chromatography/high-resolution mass spectrometry determined exact masses of apparent molecular ions and the exact masses and RIAs (relative isotopic abundances) of their +1 and +2 isotopic mass peaks, which provided their elemental compositions. Ion compositions, mass spectral libraries, the presence of related compounds, and knowledge of organic chemistry provided tentative identifications, half of which were confirmed by comparison of analyte retention times and mass spectra with those of standards.

Atomic masses and isotopic abundances are independent and complementary properties for discriminating among ion compositions. The number of possible ion compositions is greatly reduced by accurately measuring exact masses of monoisotopic ions and the relative isotopic abundances (RIAs) of the ions greater in mass by +1 Da and +2 Da. When both properties are measured, a mass error limit of 6–10 mDa (

Concentration factors of 1000 and more reveal dozens of compounds in extracts of water supplies. Library mass spectra for most of these compounds are not available, and alternative means of identification are needed. Determination of the elemental compositions of the ions in mass spectra makes feasible searches of commercial and chemical literature that often lead to compound identification. Instrumental capabilities that constrain the utility of a mass spectrometer for determining ion compositions for compounds that elute from a chromatographic column are scan speed, mass accuracy, linear dynamic range, and resolving power. Mass peak profiling from selected ion recording data (MPPSIRD) performed with a double-focusing mass spectrometer provides the best combination of these capabilities. This technique provides unique ion compositions for ions of higher mass from compounds eluting from a gas chromatograph than can be obtained by orthogonal acceleration time-of-flight (oa-TOF) or Fourier transform ion cyclotron resonance mass spectrometry. Multiple compositions are usually possible for an ion with a mass exceeding 150 Da within the error limits of the mass measurement. The correct composition is selected based on measured exact masses of the mass peak profiles resulting from isotopic ions higher in mass by 1 and 2 Da and accurate measurement of the summed abundances of these isotopic ions relative to the monoisotopic ion. A profile generation model (PGM) automatically determines which compositions are consistent with measured exact masses and relative abundances. The utility of oa-TOF and double-focusing mass spectrometry using ion composition elucidation (MPPSIRD plus the PGM) are considered for determining ion compositions of two compounds found in drinking water extracts and a third compound from a monitoring well at a landfill. Published in 2002 by John Wiley & Sons, Ltd.

Ion composition elucidation (ICE) often leads to identification of compounds and provides high-quality evidence for tracking compounds to their sources. Mass spectra for most organic compounds are not found in mass spectral libraries used to tentatively identify analytes. In addition, multiple matches are common. Ion Composition Elucidation provides the numbers of atoms of each element in the ions in the mass spectrum, greatly limiting the number of possible compounds that could produce the mass spectrum. Review of chemical and commercial literature then limits the number of possible compounds to one or a few that can be purchased to confirm tentative compound identifications by comparison of mass spectra and chromatographic retention times. Ion composition elucidation is conceptually simple relative to other analytical techniques and more easily explained to a judge or jury. It is based on sums of the exact masses of atoms and their isotopic abundances. Several applications of ICE are demonstrated for ultra-trace-level compounds in an extract of the effluent from a tertiary sewage treatment plant including: (1) measurement of five values to determine an ion’s composition and to generate evidence for the compound’s identity, (2) rejection of incorrect library matches, (3) rapid screening for a target compound in an extract, and (4) a strategy for tracking unidentified compounds to their sources.

This paper describes the application of capillary zone electrophoresis/laser-induced fluorescence detection (CZE/LIF) to the discovery of acidic compounds in environmental matrixes or the screening of extracts for acidic components. Published studies indicate that coal-derived materials contain a significant fraction of acidic compounds relative to materials derived from petroleum and shales. Such compounds may be useful as marker compounds for site assessment and source apportionment issues, and their identification may be important in toxicological and other health issues. We used deep-UV light from the frequency-doubled Ar ion laser at 244 and 257 nm to study extracts of samples. The CZE/LIF technique possesses good sensitivity and therefore overcomes one of the limitations of CZE with UV detection. The present work depends on high pressure/temperature solvent extraction of polynuclear aromatic hydrocarbon (PNA)-contaminated soil, followed by separation using CZE. The anionic analytes were separated by using borate or phosphate buffer (pH 9.2–12.3) after a chemical class separation. Samples were also characterized by gas chromatography/mass spectrometry (GC/MS) using full scans at low resolution, and elemental compositions were determined unequivocally by GC/high-resolution MS (GC/HRMS) using mass peak profiling (MPP). The similarity of low-resolution electron ionization mass spectra for a standard, 1-hydroxypyrene, and for a series of compounds in a contaminated-soil extract suggested that several types of phenolic and hydroxy-PNAs were present, including hydroxylated derivatives of fluorenes, fluoranthenes, and pyrenes. GC/HRMS using MPP confirmed the elemental compositions of the hydroxyfluorenes and hydroxypyrenes (and presumably hydroxyfluoranthenes) as [C13H10O] and [C16H10O], respectively. A new version of the MPP software was written for the Finnigan-MAT 900S-Trap and was similar to that developed previously for the VG 250SE. Inclusion of a calibration ion in addition to a lock mass ion in the multiple-ion detection descriptor provided errors of

Identification of compounds in mixtures of environmental contaminants or synthetic products is essential for regulatory analyses. Exact masses of ions determined by high resolution mass spectrometry provide unique elemental compositions only for low-mass ions (

Perfluorokerosene can almost always be used as the mass calibrant for ions produced through electron impact ionization of compounds introduced into a mass spectrometer in the gas phase. Unfortunately, no completely universal calibrant is available for ions created by electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI) of analytes introduced into a mass spectrometer in the liquid phase. ESI and APCI generally provide less sensitivity than electron impact ionization of compounds introduced in the gas phase and a portion of the weaker total signal must arise from calibrant ions. Solvent conditions must be found that provide ions from both the calibrant and analytes, or an alternative flow to the ionization region must be provided for the calibrant solution. These problems were avoided by developing a methodology to determine elemental compositions of ions without using mass calibrants. The methodology utilizes the ability of double focusing mass spectrometers to accurately measure relative abundances of ions and exact mass differences between ions. This approach should simplify analyses of environmental samples that contain mixtures of compounds not amenable to gas chromatography or volatilization from a probe. From one to five steps were used. First, from mass peak profiles of the molecular ion or protonated molecular ion, [M]+, and the [M + 1]+ and [M + 2]+ ions, abundances for the [M + 1]+ and [M + 2]+ profiles relative to the [M]+ profile were determined. The [M + 1]+ and [M + 2]+ profiles resulted from the heavier isotopes of the elements in [M]+, and the profile abundances limited the number of possible elemental compositions for [M]+. Then, to determine if [M]+ contained N atoms, the [M + 1]+ profile was observed with sufficiently high mass resolution to at least partially resolve the profiles of ions containing a 15N or a 13C atom. Next, for a prominent fragment ion, [F]+, relative abundances of the [F + 1]+ and [F + 2]+ profiles were also determined, and the [F + 1]+ profile was inspected for a profile due to 15N atoms to provide a shorter list of possible compositions for [F]+. The lists for [M]+ and [F]+ were compared, and [M]+ compositions that could not produce any possible compositions of [F]+ were rejected, as were [F]+ compositions that could not arise from any possible composition of [M]+. Fourth, exact mass differences between ions were obtained from three mass peak profiles by referencing an unknown exact mass difference against a known exact mass difference. Exact mass differences between [M]+ and [F]+ ions provided compositions of neutral losses from [M]+. Only compositions of [M]+ that could lose the observed neutral loss to provide possible compositions of [F]+ remained viable. Finally, if multiple compositions of [M]+ were still possible, profiles were obtained for [M]+ and two fragment ions resulting from known neutral losses using theoretical exact masses based on each [M]+ composition as the center masses of the three profiles. When the calibration mass option was not used in the multiple ion detector (MID) descriptor, three centered profiles were obtained only for the correct composition. This methodology was demonstrated for seven compounds with molecular weights between 159 and 318 Da. For the lowest-mass compound, only the first step was required to obtain the correct composition of [M]+ while, for the other compounds, two or more steps were needed. Copyright © 1999 John Wiley & Sons, Ltd.

An elevated incidence of childhood cancer was observed near a contaminated site. Trace amounts of several isomeric compounds were detected by gas chromatography/mass spectrometry (GC/MS) in a concentrated extract of municipal well water. No matching library mass spectra were found and Fourier transform IR and NMR analyses were not feasible due to the low concentration of the compounds. Mass peak profiling from selected-ion-recording data (MPPSIRD) provided the sensitivity and scan speed necessary to acquire mass peak profiles at mass resolutions of 10,000 to 20,000 for the molecular ion (M+) and 10 fragment ions as capillary GC peaks eluted. Using a profile generation model (PGM), the elemental composition of the molecular ion was determined from the exact masses and abundances of the M, M + 1 and M + 2 profiles. Fragment ion compositions were determined from their exact masses based on the elements in the molecular ion. Exact mass differences between the molecular and fragment ions corresponded to unique combinations of atoms for the neutral losses. Consequent reduction of the number of possible structures for the fragment ions simplified mass spectral interpretation. After inspecting library mass spectra for smaller molecules, isomeric structures were hypothesized with cyano and alkylcyano groups attached to tetralin. A literature search found such isomers produced by an industrial polymer synthesis. Three isomers in a standard form polymerization of styrene and acrylonitrile provided the same mass spectra and GC retention times as isomers in the extract.

Of four systems available from the literature, based on cyclodextrins, dioctylsulfosuccinate, bile salts, and molecular micelles consisting of oligomers of undecylenic acid, the most successful separation system in our hands is based on the molecular micelles, oligomers of sodium undecylenic acid (OSUA). We have employed organic additives of acetonitrile, acetone, and tetrahydrofuran in achieving separations of polyaromatic hydrocarbons (PNAs) using molecular micelles. Generally, successful separations are achieved with 20-40% composition as the organic additive in an 8 mM borate buffer. We separated 16 PNAs with 20% tetrahydrofuran in a system of 8 mM borate and 0.125 g/10 mL (ca. 6.25 mM) of OSUA. Typical extracts of environmental samples contain additional analytes besides the typical 16 target compounds. Among these are the nitrogen-containing aromatics that can act as cations under conditions of low pH and additional compounds that can act as anions under basic conditions in free-zone electrophoresis. These additional classes of analytes are separated by capillary zone electrophoresis/laser-induced fluorescence detection using a frequency-doubled laser operated at 257 nm.

To identify elemental compositions of ions, a mass peak profile generation model (PGM) was developed to plan data acquisitions and to interpret the data obtained by using a high resolution mass spectrometer (VG70-250SE). The PGM provides a list of all compositions possible for the exact mass of ion M and its error range from which the user selects a hypothetical composition. The PGM then plots [M + 1] and [M + 2] mass peak profiles and calculates masses and abundances of full and partial [M + 1] and [M + 2] profiles relative to the M profile. All possible compositions, calculated values for the exact masses and relative abundances, and measures of profile broadening and the shape of the [M + 2] profile are listed in a table. Pass-fail results for each of six criteria based on a comparison between table entries for the hypothetical composition and each of the other compositions are indicated. Compositions failing one or more criteria will be eliminated if the hypothetical composition is correct. The table provides assurance that all possible compositions based on the elements specified by the user have been considered. The PGM can be used to estimate the minimum resolution and number of determinations necessary to identify the correct composition by eliminating all others. As multiple determinations are made and error limits become smaller, average values are entered into the PGM to determine all compositions consistent with the data, often until only one composition remains.

The relative abundances of M + 1 and M + 2 ions help to identify the elemental composition of the molecular ion (M). But scan speed, sensitivity, and resolution limitations of mass spectrometers have impeded determination of these abundances. Mass peak profiling from selected ion recording data (MPPSIRD) provided faster sampling and enhanced sensitivity, which permitted use of higher resolution. M + 2 profiles having only a few percent of the ion abundance of M were monitored at 20 000 resolution. The relative abundances, exact masses, and shapes of M, M + 1, and M + 2 mass peak profiles were determined. By applying five criteria based on these quantities, elemental compositions were determined even for ions too large (up to 766 Da) to be uniquely assigned from their exact mass and accuracy limits alone. A profile generation model (PGM) was written to predict these resolution-dependent quantities by considering all M + 1 and M + 2 ions for each candidate composition. The model also provided assurance that no other compositions were possible. Characterization of the M + 1 and M + 2 profiles by MPPSIRD and the PGM greatly expanded the practical ability of high-resolution mass spectrometry to determine elemental compositions.

A new scanning strategy permits on-line determination of exact masses and relative abundances of ions produced from analytes as they are separated chromatographically and analyzed by a high-resolution mass spectrometer. Tentative identifications of compounds based on library matches of their background subtracted mass spectra can now be confirmed or refuted by applying 6 criteria based on the molecular ion (M), M + 1, and M+2 mass peak profiles. This article reviews the technique, demonstrates its most common application, and lists some of its other uses.

Applications of capillary electrophoresis (CE) and capillary liquid chromatography (LC) to environmental analysis have been limited. In this work we present applications of micellar electrokinetic chromatography (MEKC) to the analysis of environmental matrices for synthetic dyes. Separations obtained by capillary LC are compared with those obtained under MEKC for seven selected dyes. Both techniques are capable of resolving the subject compounds at high efficiency. Recovery data for spiked water and soil matrices were obtained for four dyes using solid-phase extraction cartridges and disks with determination by MEKC-UV detection. Both pH adjustment via acid and ion-pairing via a cationic surfactant were investigated for isolating dyes. Capillary LC detection was by continuous-flow liquid secondary ion mass spectrometry (CF-LSI-MS) whereas MEKC used UV detection (214 nm). Application of peak-profiling at high mass resolution is illustrated with the capillary LC-MS technique. Interfacing capillary LC under CF-LSI-MS using the coaxial arrangement is easier than interfacing CE with this arrangement. MEKC provides a powerful screening and determinative technique, while capillary LC-MS provides a confirmatory tool.

Methamphetamine (meth) from meth syntheses or habitual meth smoking deposited on household surfaces poses human health hazards. The U.S. State Departments of Health require decontamination of sites where meth was synthesized (meth labs) before they are sold. National Institute for Occupational Safety and Health (NIOSH) methods for meth analysis require wipe sampling, extraction, clean-up, solvent exchange, derivatization, and/or mass spectral analysis using selected ion monitoring. Rapid and inexpensive analyses could screen for drug-contamination within structures with greater spatial resolution, provide real-time analyses during decontamination, and provide thorough documentation of successful clean ups. Herein an autosampler/open-air ion source time-of-flight mass spectrometric technique is described that required only direct sampling using cotton-swab wipes. Each wipe sample collection required 2 min and data acquisition required only 13 s per sample. Optimum collision-induced dissociation voltages, desorption gas temperatures, and wipe sample solvents were determined for 11 drugs. Peaks were observed in analyte-ion traces for 0.025 µg/100 cm(2) of meth and seven other drugs. This level is half the detection limit of NIOSH methods and one-fourth of the lowest U.S. state decontamination limit for meth. Dynamic ranges of 100 in concentration were demonstrated for eight drugs, which is sufficient for a screening technique. The volatilities of 11 drugs deposited on glass were determined. The pick up of the drugs by solvent-soaked cotton-swab wipes from glass relative to acrylic latex paint was also compared.

Toxaphene is extracted from soil by standard procedures using Soxhlet or sonication methods. The extract is fractionated by high-performance gel permeation chromatography (HPGPC), which separates toxaphene from the bulk of co-extractives including polychlorinated biphenyls. This HPGPC fractionation has broad application to many problems of environmental analysis. A solid-phase extraction cleanup with silica gel further removes any polar components present in the collected fraction. Determination of toxaphene is accomplished by electron-capture negative ion mass spectrometry (ECNI-MS) after introduction by capillary gas chromatography. Levels down to 100 μg/kg in soil are obtainable. Brief mention is made of high-resolution ECNI-MS carried out at a resolution of 10 000.

A combined approach using gas chromatographic retention indices and mass spectrometric characteristics has been elaborated for the isomer-specific identification of the 1700 bromo-, chloro- and bromochloro-dioxins which may be found in the environment. Over 100 dioxins were synthesized to develop this approach. This environmental monitoring strategy allows qualitative and quantitative monitoring of the 2,3,7,8-substituted isomers, which are considered to be more toxic, and many of which have assigned toxicity equivalency factors.

A model-correlating structure with gas chromatographic retention index was developed to assist in making positional isomer assignments for dioxins halogenated by bromine and/or chlorine using commercially available standards and synthetic mixtures. Bromodibenzofuran assignments were made using pyrolysate mixtures, assuming the elution order was the same as for chlorinated dibenzofurans. These strategies can be used, on an interim basis, for isomer assignments in environmental monitoring efforts.

After an accidental, deliberate, or weather-related dispersion of chemicals (dispersive event), rapid determination of elemental compositions of ions in mass spectra is essential for tentatively identifying compounds. A direct analysis in real time (DART)ion source interfaced to a JEOL AccuTOFmass spectrometer provided exact masses accurate to within 2 mDa for most ions in full scan mass spectra and relative isotopic abundances (RIAs) accurate to within 15-20% for abundant isotopic ions. To speed determination of the correct composition for precursor ions and most product ions and neutral losses, a three-part software suite was developed. Starting with text files of m/z ratios and their ion abundances from mass spectra acquired at low, moderate, and high collision energies, the ion extraction program (IEP) compiled lists for the most abundant monoisotopic ions of their exact masses and the RIAs of the +1 and +2 isotopic peaks when abundance thresholds were met; precursor ions; and higher-mass, precursor-related species. The ion correlation program (ICP) determined if a precursor ion composition could yield a product ion and corresponding neutral loss compositions for each product ion in turn. The input and output program (IOP) provided the ICP with each precursor ion:product ion pair for multiple sets of error limits and prepared correlation lists for single or multiple precursor ions. The software determined the correct precursor ion compositions for 21 individual standards and for three- and seven-component mixtures. Partial deconvolution of composite mass spectra was achieved based on exact masses and RIAs, rather than on chromatography.

At least 36 million pounds of brominated flame retardants are used in the U.S. annually. Most if not all of these materials enter the waste stream via landfilled plastic waste, municipal incinerator fly ash, or automotive fluff waste. Analytical methodology is summarized which is suitable for environmental monitoring of these wastes, and the significance of the analytical results is discussed.

Relative efficiencies of various sample preparation techniques were measured for analysis of chlorinated dioxins and dibenzofurans (PCDD, PCDF) in representative wastes. The following sample cleanup columns were tested: a mixed phase column of acid, base, and neutral silica; neutral and acidic alumina columns; Carbopack/Celite and AX-21 carbon adsorption columns. Chlorinated dioxins and dibenzofurans were analyzed in fly ash, still bottom, fuel oil, and sludge matrices for this study. The multi-phase silica, acidic alumina, and AX-21 columns were determined to be the most suitable combination for PCDD and PCDF analytes.

Phomodione, [(4a S ∗ ,9b R ∗ )-2,6-diacetyl-7-hydroxy-4a,9-dimethoxy-8,9b-dimethyl-4a.9b-dihydrodibenzo[ b , d ]furan-1,3(2 H ,4 H )-dione], an usnic acid derivative, was isolated from culture broth of a Phoma species, discovered as an endophyte on a Guinea plant ( Saurauia scaberrinae ). It was identified using NMR, X-ray crystallography, high resolution mass spectrometry, as well as infrared and Raman spectroscopy. In addition to phomodione, usnic acid and cercosporamide, known compounds with antibiotic activity, were also found in the culture medium. Phomodione exhibited a minimum inhibitory concentration of 1.6 μg/mL against Staphylococcus aureus using the disk diffusion assay, and was active against a representative oomycete, ascomycete and basidiomycete at between three and eight micrograms per mL.

Exact masses of monoisotopic ions, and the relative isotopic abundances (RIAs) of ions greater in mass by 1 and 2 Da than the monoisotopic ion, are independent and complementary physical properties useful for distinguishing among elemental compositions of ions possible for a given nominal mass. Using these properties to determine elemental compositions of product ions and neutral losses increases the masses of precursor ions for which unique compositions can be determined. Compositions of the precursor ion, product ion, and neutral loss aid mass spectral interpretation and guide modest chemical literature searches for candidate standards to be obtained for confirmation of tentative compound identifications. This approach is essential for compound characterization or identification due to the absence of commercial libraries of electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) product ion spectra. For a series of 34 exact mass measurements, an orthogonal acceleration time-of-flight mass spectrometer provided 34 and 29 values accurate to within 2 and 1 mDa, respectively, for ions from eight simulated unknowns with [M+H]+ ion masses between 166 and 319 Da. Of 36 RIA measurements for +1 Da or +2 Da ions, 35 were accurate to within 20% of their predicted values (or to within 0.4 RIA % when the RIA value was less than 1%) in the absence of obvious interferences, in cases where the monoisotopic ion peak areas were at least 1.7 × 105 counts and the ion masses exceeded 141 Da. An ion correlation program (ICP) provided the unique and correct compositions for all but three of the 34 ions studied. Manual inspection of the data eliminated the incorrect compositions. To test the utility of the ICP for deconvoluting composite product ion spectra, all 34 ions were tested for correlation. Six of eight precursor ions were identified as such, while two were compositional subsets of others and were not properly identified. The six precursor ion compositions were still found by the ICP even though ions with masses less than 158 Da were not considered since they could no longer be correlated with a single precursor ion. Finally, two unidentified analytes were characterized, based on data published by others and using the ICP together with mass spectral interpretation. Published in 2005 by John Wiley & Sons, Ltd.

Plotting of mass peak profiles at high mass resolution for chromatographic peaks of low ion abundance is possible from single-ion monitoring data due to the high sensitivity and low cycle time for single-ion monitoring. The mass profiles provide accurate masses, document mass resolution at a mass as a chromatographic peak elutes and provide relative abundances for two ions at the same nominal mass. A personal computer is used to plot the mass peak profiles.

Capillary zone electrophoresis/laser-induced fluorescence has been used to study extracts from environmental sites. We have used deep UV (244, 257 nm) laser light, obtaining good sensitivity. We have studied PNA-contaminated soil samples and creosote extract. Confirming analysis has been performed using mass-peak-profiling mass spectrometry. The results may be relevant to site assessment and source apportionment.

An atmospheric pressure ionization (API) source for a VG 7070E‐HF mass spectrometer has been built and successfully operated at an accelerating potential of 6 kV. Hydrated protons and hydrated organic ions formed in the API source can be either partially or completely disaggregated by collisionally induced dissociation before entering the mass analyzer. The protonated molecular ions of pinacolone and 2,4‐pentanedione can be fully separated (R=2800, m/z 101

Certain thermoplastic resins, brominated diphenyl ether flame retardants, a pyrolysate and fumes collected during resin extrusion were analyzed for brominated dibenzofurans (PBDF) to assess the potential for encountering PBDF in the environment. EPA methods (RCRA Method 8280 and CERCLA IFB WA84-A002) were modified as needed to allow determination of PBDF in these matrices. Except for the base resins, all samples were found to contain PBDF. The pyrolysate also contained compounds whose structures were assigned to be brominated dioxins (PBDD) and possibly brominated xanthenes (PBX) or methyl-PBDF.

An electrical discharge suppression system for a medium throughput (∼2 l/s) pumping line has been devised that works up to potentials of ±15 kV. This device permits atmospheric pressure ionization sources to be interfaced to high‐resolution, magnetic sector mass spectrometers with source potentials of 6–10 kV.