Measurement of isoprene nitrates by GCMS

Abstract. An instrument based on gas chromatography/mass spectrometry (GCMS) and the associated calibration methods are described for the speciated measurements of individual isoprene nitrate isomers. Five of the primary isoprene nitrates formed by reaction of isoprene with the hydroxyl radical (OH) in the Master Chemical Mechanism are identified using known isomers on two column phases, and are fully separated on the Rtx-200 column. Three primary isoprene nitrates from the reaction of isoprene with the nitrate radical (NO3) are identified after synthesis from the already identified analogous hydroxy nitrate.

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Measurement of isoprene nitrates by GCMS

Atmospheric Measurement Techniques ◽

10.5194/amt-9-4533-2016 ◽

2016 ◽

Vol 9 (9) ◽

pp. 4533-4545 ◽

Cited By ~ 6

Author(s):

Graham P. Mills ◽

Glyn D. Hiatt-Gipson ◽

Sean P. Bew ◽

Claire E. Reeves

Keyword(s):

Atmospheric Chemistry ◽

Production Efficiency ◽

Chemical Mechanism ◽

Ozone Production ◽

Gas Chromatography Mass Spectrometry ◽

Nitrate Radical ◽

Calibration Methods ◽

Isoprene Nitrates ◽

Ambient Concentrations ◽

Master Chemical Mechanism

Abstract. According to atmospheric chemistry models, isoprene nitrates play an important role in determining the ozone production efficiency of isoprene; however this is very poorly constrained through observations as isoprene nitrates have not been widely measured. Measurements have been severely restricted largely due to a limited ability to measure individual isoprene nitrate isomers. An instrument based on gas chromatography/mass spectrometry (GCMS) and the associated calibration methods are described for the speciated measurements of individual isoprene nitrate isomers. Five of the primary isoprene nitrates which formed in the presence of NOx by reaction of isoprene with the hydroxyl radical (OH) in the Master Chemical Mechanism are identified using known isomers on two column phases and are fully separated on the Rtx-200 column. Three primary isoprene nitrates from the reaction of isoprene with the nitrate radical (NO3) are identified after synthesis from the already identified analogous hydroxy nitrate. A Tenax adsorbent-based trapping system allows the analysis of the majority of the known hydroxy and carbonyl primary isoprene nitrates, although not the (1,2)-IN isomer, under field-like levels of humidity and showed no impact from typical ambient concentrations of NOx and ozone.

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Abiotic conversion of dihydrophloroglucinol to resorcinol

Canadian Journal of Microbiology ◽

10.1139/m93-135 ◽

1993 ◽

Vol 39 (9) ◽

pp. 899-902 ◽

Cited By ~ 4

Author(s):

S. M. Armstrong ◽

T. R. Patel

Keyword(s):

Mass Spectrometry ◽

Gas Chromatography ◽

Chemical Conversion ◽

Chemical Mechanism ◽

Gas Chromatography Mass Spectrometry ◽

Infrared Spectrometry ◽

Ultraviolet Spectrophotometry ◽

Ph Values ◽

Chromatography Mass Spectrometry ◽

Layer Chromatography

Chemical conversion of a dihydrophloroglucinol preparation (a mixture of the tautomers 1,3,5-trihydroxy-1,3-cyclohexadiene, 1,3-dioxo-5-hydroxycyclohexane, and 3,5-dihydroxy-3-cyclohexene-1-one) to resorcinol occurred during a 24-h extraction of an acidic (pH 2.0) aqueous dihydrophloroglucinol preparation into ethyl acetate. This conversion did not occur at neutral pH, nor did phloroglucinol (1,3,5-trihydroxybenzene)-induced or succinate-induced Penicillium simplicissimum enzyme extracts convert the dihydrophloroglucinol preparation to resorcinol at pH values of 5.5–8.0. The chemical structure of the dihydrophloroglucinol preparation was determined by gas chromatography - mass spectrometry, high resolution 13C and 1H nuclear magnetic resonance, Fourier-transformed infrared spectrometry, and ultraviolet spectrophotometry. Resorcinol (1,2-dihydroxybenzene) was detected by gas chromatography - mass spectrometry or thin-layer chromatography and ultraviolet spectrophotometry. A chemical mechanism for the conversion of the dihydrophloroglucinol preparation to resorcinol is proposed.Key words: dihydrophloroglucinol, chemical conversion, resorcinol.

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