Graphene nanoribbons as flexible docks for chemiresistive sensing of gas phase explosives

Abstract. Volatilization and subsequent processing in the atmosphere is an important environmental pathway for the transport and chemical fate of pesticides. However, these processes remain a particularly poorly understood component of pesticide lifecycles due to analytical challenges. Most pesticide measurements require long (hours to days) sampling times coupled with off-line analysis, inhibiting observation of meteorologically driven events or investigation of rapid oxidation chemistry. Here, we present chemical ionization time-of-flight mass spectrometry with iodide reagent ions as a fast and sensitive measurement of four current-use pesticides. These semi-volatile pesticides were calibrated with injections of solutions onto a filter and subsequently volatilized to generate gas phase analytes. Trifluralin and atrazine are detected as iodide-molecule adducts, while permethrin and metolachlor are detected as adducts between iodide and fragments of the parent analyte molecule. Limits of detection (1 second) are 0.37, 0.67, 0.56, and 1.1 µg/m3 for gas phase trifluralin, metolachlor, atrazine and permethrin, respectively. The sensitivities of trifluralin and metolachlor depend on relative humidity, changing as much as 70 % and 59 %, respectively, as relative humidity of the sample air varies from 0 to 80 %. This measurement approach is thus appropriate for laboratory experiments and potentially near-source field measurements.

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Gas-phase pesticide measurement using iodide ionization time-of-flight mass spectrometry

Atmospheric Measurement Techniques ◽

10.5194/amt-10-2117-2017 ◽

2017 ◽

Vol 10 (6) ◽

pp. 2117-2127 ◽

Cited By ~ 8

Author(s):

Trey Murschell ◽

S. Ryan Fulgham ◽

Delphine K. Farmer

Keyword(s):

Mass Spectrometry ◽

Relative Humidity ◽

Gas Phase ◽

Time Of Flight ◽

Field Measurements ◽

Analyte Molecule ◽

Ionization Time ◽

Flight Mass Spectrometry ◽

Oxidation Chemistry ◽

Sampling Times

Abstract. Volatilization and subsequent processing in the atmosphere are an important environmental pathway for the transport and chemical fate of pesticides. However, these processes remain a particularly poorly understood component of pesticide lifecycles due to analytical challenges in measuring pesticides in the atmosphere. Most pesticide measurements require long (hours to days) sampling times coupled with offline analysis, inhibiting observation of meteorologically driven events or investigation of rapid oxidation chemistry. Here, we present chemical ionization time-of-flight mass spectrometry with iodide reagent ions as a fast and sensitive measurement of four current-use pesticides. These semi-volatile pesticides were calibrated with injections of solutions onto a filter and subsequently volatilized to generate gas-phase analytes. Trifluralin and atrazine are detected as iodide–molecule adducts, while permethrin and metolachlor are detected as adducts between iodide and fragments of the parent analyte molecule. Limits of detection (1 s) are 0.37, 0.67, 0.56, and 1.1 µg m−3 for gas-phase trifluralin, metolachlor, atrazine, and permethrin, respectively. The sensitivities of trifluralin and metolachlor depend on relative humidity, changing as much as 70 and 59, respectively, as relative humidity of the sample air varies from 0 to 80 %. This measurement approach is thus appropriate for laboratory experiments and potentially near-source field measurements.

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Residual Gas Reactions in the Electron Microscope: I. Qualitative Observations on the Water Gas Reaction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100101207 ◽

1968 ◽

Vol 26 ◽

pp. 292-293

Author(s):

Richard E. Hartman ◽

Roberta S. Hartman ◽

Peter L. Ramos

Keyword(s):

Electron Beam ◽

Electron Microscope ◽

Gas Phase ◽

Absolute Temperature ◽

Residual Gas ◽

Gas Reactions ◽

Image Position ◽

The Right ◽

Water Gas ◽

Thinning Rate

The action of water and the electron beam on organic specimens in the electron microscope results in the removal of oxidizable material (primarily hydrogen and carbon) by reactions similar to the water gas reaction .which has the form:The energy required to force the reaction to the right is supplied by the interaction of the electron beam with the specimen.The mass of water striking the specimen is given by:where u = gH2O/cm2 sec, PH2O = partial pressure of water in Torr, & T = absolute temperature of the gas phase. If it is assumed that mass is removed from the specimen by a reaction approximated by (1) and that the specimen is uniformly thinned by the reaction, then the thinning rate in A/ min iswhere x = thickness of the specimen in A, t = time in minutes, & E = efficiency (the fraction of the water striking the specimen which reacts with it).

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Integration of Core-Edge Spectroscopy Methods for the Study of Polymers

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010016323x ◽

1996 ◽

Vol 54 ◽

pp. 154-155

Author(s):

E. G. Rightor

Keyword(s):

Excited State ◽

Polymer Blends ◽

Gas Phase ◽

Spatial Resolution ◽

High Spatial Resolution ◽

Electronic States ◽

Core Electron ◽

Bulk Solids ◽

Development Application

Core edge spectroscopy methods are versatile tools for investigating a wide variety of materials. They can be used to probe the electronic states of materials in bulk solids, on surfaces, or in the gas phase. This family of methods involves promoting an inner shell (core) electron to an excited state and recording either the primary excitation or secondary decay of the excited state. The techniques are complimentary and have different strengths and limitations for studying challenging aspects of materials. The need to identify components in polymers or polymer blends at high spatial resolution has driven development, application, and integration of results from several of these methods.

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