Improved method for estimating molecular weights of volatile organic compounds from low resolution mass spectra

1991 ◽  
Vol 12 (2) ◽  
pp. 189-200 ◽  
Author(s):  
Donald R. Scott
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Mass Spectra ◽  
Improved Method ◽  
Low Resolution ◽  
Molecular Weights ◽  
Volatile Organic ◽  
Resolution Mass

scholarly journals Storage Stability of Volatile Organic Compounds from Petrochemical Plant of China in Different Sample Bags

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Fenglei Han ◽  
Huangrong Zhong ◽  
Ting Li ◽  
Yongqiang Wang ◽  
Fang Liu
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Recovery Rate ◽  
Storage Stability ◽  
Petrochemical Plant ◽  
Pure Nitrogen ◽  
Molecular Weights ◽  
Volatile Organic ◽  
Protective Gas ◽  
The Impact

According to the emission characteristics of volatile organic compounds (VOCs) in the petrochemical plants of China, the storage stability of VOCs for two different bags, polyester aluminum (PEA) and polyvinyl fluoride (PVF), was investigated in this study by comparing the adsorption of gas samples. A series of experiments were carried out to study the impact of different factors of sampling in the petrochemical industry. The results showed that the C2∼C3 substances can be adsorbed by the Tedlar bag, and after being refilled with pure nitrogen, the VOCs adsorbed previously by the bag material can be released. The aromatic hydrocarbon VOCs with larger molecular weight had a relatively lower recovery rate than the smaller molecular weights. And the average recovery of PEA airbags was significantly better than that of PVF airbags for storing stationary VOCs in the refinery of China. More kinds of substances can be detected in the airbags that had been added with helium protective gas, and it had a higher recovery rate for both kinds of simple bags after 24 hours of storage time, which indicated that the airbags without protective gas had adsorbed these substances.

Vacuum Ultraviolet Photoionization Mass Spectra and Cross-Sections for Volatile Organic Compounds at 10.5 eV

2007 ◽  
Vol 61 (8) ◽  
pp. 896-902 ◽  
Author(s):  
Nozomu Kanno ◽  
Kenichi Tonokura
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Cross Sections ◽  
Mass Spectra ◽  
Vacuum Ultraviolet ◽  
Single Photon ◽  
Photoionization Cross Section ◽  
Oxygenated Compounds ◽  
Flight Mass Spectrometry ◽  
Volatile Organic

Vacuum ultraviolet single-photon ionization time-of-flight mass spectrometry (VUV-SPI-TOFMS) has been applied to the detection of volatile organic compounds (VOCs), including aromatic, chlorinated, and oxygenated compounds. Photoionization mass spectra of 23 VOCs were measured using SPI-TOFMS at 10.5 eV (118 nm). The limits of detection of VOCs using SPI-TOFMS at 10.5 eV were estimated to be a few ppbv. The mass spectra of 20 VOCs exhibit only the parent ion and its isotopes' signals. The ionization processes of the VOCs were discussed on the basis of the reaction enthalpies predicted by the quantum chemical calculations. Absolute photoionization cross-sections for 23 VOCs, including 12 newly measured VOCs, at 10.5 eV were determined in comparison to the reported absolute photoionization cross-section of NO.

scholarly journals Volatile and Non-Volatile Organic Compounds Stimulate Oviposition by Aphidophagous Predators

Insects ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 683
Author(s):  
Eric W. Riddick
Keyword(s):  
Molecular Weight ◽  
Volatile Organic Compounds ◽  
Vapor Pressure ◽  
Organic Compounds ◽  
Egg Production ◽  
United States Department ◽  
Oviposition Stimulants ◽  
Molecular Weights ◽  
Production Ratio ◽  
Volatile Organic

Introduction: Evidence that volatile organic compounds (VOCs) and non-VOCs stimulate oviposition by aphidophagous predators is scattered throughout the literature. The objectives of this review are to (1) compile records indicating that VOCs and non-VOCs are responsible for oviposition stimulation, (2) calculate an egg production ratio (EPR) for stimulated predators, and (3) determine if EPR is correlated with vapor pressure and molecular weight of active compounds. Methods: The USDA (United States Department of Agriculture), National Agricultural Library, online digital catalog system was used to retrieve abstracts, then the full text of manuscripts on oviposition stimulants for predators. Oviposition-stimulating VOCs and non-VOCS were tabulated with molecular weights and vapor pressure estimates. EPRs were calculated for stimulated coccinellids, syrphids, and chrysopids. Results: Both VOCs and non-VOCs stimulated oviposition behavior by coccinellids and syrphids, but not chrysopids. EPR was greatest for syrphids. Two VOCs, (E)-β-farnesene and 3-methyl-2-butenal, stimulated very high EPR values by the syrphid Episyrphusbalteatus. Regardless of predator taxa, EPR was negatively and positively correlated with molecular weight and vapor pressure, respectively. Conclusions: Syrphids (rather than coccinellids or chrysopids) produce more eggs in response to VOCs. Organic compounds with low-to-moderate molecular weights and moderate-to-high vapor pressures might be most effective oviposition stimulants for aphidophagous predators.

Ion-Trap Detection of Volatile Organic Compounds in Alveolar Breath

1992 ◽  
Vol 38 (1) ◽  
pp. 60-65 ◽  
Author(s):  
M Phillips ◽  
J Greenberg
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Molecular Sieve ◽  
Mass Spectra ◽  
Ion Trap ◽  
Normal Subjects ◽  
Human Breath ◽  
Human Volunteers ◽  
Volatile Organic ◽  
Computer Based

Abstract We describe a method for the collection and microanalysis of the volatile organic compounds in human breath. A transportable apparatus supplies subjects with purified air and samples their alveolar breath; the volatile organic compounds are captured in an adsorptive trap containing activated carbon and molecular sieve. The sample is thermally desorbed from the trap in an automated microprocessor-controlled device, concentrated by two-stage cryofocusing, and assayed by gas chromatography with ion-trap detection. Compounds are identified by reference to a computer-based library of mass spectra with subtraction of the background components present in the inspired air. We used this device to study 10 normal subjects and determined the relative abundance of the volatile organic compounds in their alveolar breath. The breath-collecting apparatus was convenient to operate and was well tolerated by human volunteers.

scholarly journals Measurement report: Important contributions of oxygenated compounds to emissions and chemistry of volatile organic compounds in urban air

2020 ◽  
Vol 20 (23) ◽  
pp. 14769-14785
Author(s):  
Caihong Wu ◽  
Chaomin Wang ◽  
Sihang Wang ◽  
Wenjie Wang ◽  
Bin Yuan ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Mass Spectrometer ◽  
Mass Spectra ◽  
Urban Atmosphere ◽  
Urban Site ◽  
Oh Radicals ◽  
Secondary Formation ◽  
Volatile Organic ◽  
Tof Ms

Abstract. Volatile organic compounds (VOCs) play important roles in the tropospheric atmosphere. In this study, VOCs were measured at an urban site in Guangzhou, one of the megacities in the Pearl River Delta (PRD), using a gas chromatograph–mass spectrometer/flame ionization detection (GC–MS/FID) and a proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS). Diurnal profile analyses show that stronger chemical removal by OH radicals for more reactive hydrocarbons occurs during the daytime, which is used to estimate the daytime average OH radical concentration. In comparison, diurnal profiles of oxygenated volatile organic compounds (OVOCs) indicate evidence of contributions from secondary formation. Detailed source analyses of OVOCs, using a photochemical age-based parameterization method, suggest important contributions from both primary emissions and secondary formation for measured OVOCs. During the campaign, around 1700 ions were detected in PTR-ToF-MS mass spectra, among which there were 462 ions with noticeable concentrations. VOC signals from these ions are quantified based on the sensitivities of available VOC species. OVOC-related ions dominated PTR-ToF-MS mass spectra, with an average contribution of 73 % ± 9 %. Combining measurements from PTR-ToF-MS and GC–MS/FID, OVOCs contribute 57 % ± 10 % to the total concentration of VOCs. Using concurrent measurements of OH reactivity, OVOCs measured by PTR-ToF-MS contribute greatly to the OH reactivity (19 % ± 10 %). In comparison, hydrocarbons account for 21 % ± 11 % of OH reactivity. Adding up the contributions from inorganic gases (48 % ± 15 %), ∼ 11 % (range of 0 %–19 %) of the OH reactivity remains `missing”, which is well within the combined uncertainties between the measured and calculated OH reactivity. Our results demonstrate the important roles of OVOCs in the emission and evolution budget of VOCs in the urban atmosphere.

scholarly journals Profile of the volatile organic compounds of pink pepper and black pepper

2021 ◽  
Vol 14 (12) ◽  
Author(s):  
Yuri Gomes Figueiredo ◽  
Fabio Corrêa Bueno ◽  
Afonso Henrique de Oliveira Júnior ◽  
Ana Carolina do Carmo Mazzinghy ◽  
Henrique de Oliveira Prata Mendonça ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Solid Phase Microextraction ◽  
Mass Spectra ◽  
Solid Phase ◽  
Black Pepper ◽  
Piper Nigrum ◽  
Gas Chromatograph ◽  
Centers Of Origin ◽  
Volatile Organic

Black pepper (Piper nigrum L.) and pink pepper (Schinus terebinthifolius Raddi) are two plant-based spices, which despite having a common popular name, have a botanical family and distinct centers of origin. Its fruits are known worldwide in cuisine as condiments; in addition, the extraction of essential oil from these species is interesting from a pharmacological and industrial perspective. In this sense, the present study aimed to analyze the chemical profile of volatile organic compounds (VOC's) present in black pepper and pink pepper. The solid phase microextraction method in headspace mode (HS-SPME) was used, using the fiber, polydimethylsiloxane-divinylbenzene (PDMS/DVB) for the extraction of VOCs. In the extraction of volatile compounds, 2g of the seeds of each sample were used, previously ground in an analytical mill, and placed in a 20 ml headspace flask. The adsorption of the compounds was carried out at a temperature of 60ºC, for 20 minutes, with the exposed PDMS/DVB fiber, after extraction, the desorption was carried out in the gas chromatograph injector coupled to mass spectrometry (CG-MS), where the fiber was exposed for 5 minutes. The identification of VOCs was performed by comparing the mass spectra obtained with data from the NIST library. Thirty-six volatile organic compounds (VOCs) were identified and quantified among pink pepper and black pepper seed samples. Of which 16 were found in black pepper, and 20 in pink pepper. These compounds are divided into monoterpenes, sesquitepenes, and other classes such as alkaloids and sesquiterpenoids. The volatile organic compounds found in higher concentrations in black pepper were Carnegine with 36.32 %, beyerene (30.84%), alpha-gurjunene (6.10%) and 1R,4S,7S,11R-2, 2,4,8-Tetramethyltricyclo [5.3.1.0 (4.11)] undec-8-ene also with 6.10%. In pink pepper, the compounds with the highest concentrations were, phyllocladene (36.16%), 3-carene (12.49%), and 1R,4S,7S,11R-2,2,4,8-tetramethyltricyclo [ 5.3.1.0 (4.11)] undec-8-ene (12.43%).

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