Andrew H. Grange

Detection of illicit drugs on surfaces using direct analysis in real time (DART) time‐of‐flight mass spectrometry

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.

Capillary liquid chromatography-mass spectrometry and micellar electrokinetic chromatography as complementary techniques in environmental analysis

Abstract 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.

Automated determination of precursor ion, product ion, and neutral loss compositions and deconvolution of composite mass spectra using ion correlation based on exact masses and relative isotopic abundances

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.

Semi-quantitative analysis of contaminants in soils by direct analysis in real time (DART) mass spectrometry

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.

An Integrated Wipe Sample Transport/Autosampler to Maximize Throughput for a Direct Analysis in Real Time (DART)/Orthogonal Acceleration, Time-of-Flight Mass Spectrometer (oa-TOFMS)

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.

A mass peak profile generation model to facilitate determination of elemental compositions of ions based on exact masses and isotopic abundances

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.

An Inexpensive Autosampler to Maximize Throughput for an Ion Source that Samples Surfaces in Open Air

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.

Mass spectrometric identification of an azobenzene derivative produced by smectite-catalyzed conversion of 3-amino-4-hydroxyphenylarsonic acid

The compound 3-amino-4-hydroxyphenylarsonic acid (3-amino-HPAA) reacts with smectite to form a soluble azobenzene arsonic acid compound. This reaction is of particular interest because it provides a possible mechanism for the formation of a new type of arsenic compound in natural water systems. 3-Amino-HPAA is a degradation product excreted by chickens that are fed rations amended with roxarsone. Roxarsone is used to control coccidial intestinal parasites in most of the broiler chickens grown in the United States. The structure of the azobenzene arsonic acid compound was first inferred from negative-ion and positive-ion low-resolution mass-spectrometric analyses of the supernatant of the smectite suspension. Elemental composition of the parent ion determined by high-resolution positive-ion mass spectrometric measurements was consistent with the proposed structure of the azobenzene arsonic acid compound.

Correlation of structure with linear retention index for bromo- and bromochlorodibenzo-p-dioxins and bromodibenzofurans

Abstract 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.

Identification of pollutants in a municipal well using high resolution mass spectrometry.

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.