Jörgen R. Pedersen

Soxhlet extraction of acrylamide from potato chips

The problem of complete extraction of acrylamide from potato chips was investigated. A method was developed based on the Soxhlet extraction technique. A defatted sample was extracted continuously with methanol, for 10 days, in a Soxhlet extractor. After about 7 days, a constant concentration of acrylamide was reached. This indicates that all the acrylamide that could be removed from the sample had been extracted. Acrylamide was identified in the extract using GC-MS and scan mode. Total concentration was 14500 microg kg(-1) using GC-FID and standard additions. Complementary determinations, using an external standard (GC-FID and GC-MS) and an internal standard (GC-FID), showed results within +/- 5%. A previously published study, using a static extraction method and GC-MS and LC-MS-MS, showed concentrations of 2287 and 1993 microg kg(-1), respectively. The results are discussed in relation to a recent model and analogous experiments. The extracted amount of acrylamide is affected by several parameters: solvent properties, solvent volume, extraction time, temperature, particle size, and the microstructure of the sample.

Formation of chlorinated organic compounds during combustion of propane in the presence of HCl

Abstract Combustion of propane in the presence of hydrochloric acid yields a complicated mixture of chlorinated compounds some of which are known to be precursors to chlorinated dibenzo-p-dioxins and dibenzofurans.

Methane, hydrogen chloride and oxygen form a wide range of chlorinated organic species in the temperature range 400°C–950°C☆

Abstract Methane, hydrogen chloride and oxygen at high temperatures yield a mixture of chlorinated alkanes, -alkenes, -aromatics as well as polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) containing up to 3 chlorine atoms. The pattern of products formed is similar to the distribution of chlorinated micro-pollutants found in flue gases from municipal waste incinerators. Dibenzo-p-dioxin and dibenzofuran react with hydrochloric acid at 400°C in sealed ampoules. The products are the components of the high temperature equilibrium reactions of chlorinated alkanes besides PCDDs and PCDFs. These results suggest that PCDDs and PCDFs are formed in a chain of reversible reactions starting with chloromethanes.

OXIDATION OF RAPESEED OIL, RAPESEED METHYL ESTER (RME) AND DIESEL FUEL STUDIED WITH GC/MS.

Abstract Small samples (5 μl) of rapeseed oil, rapeseed oil methyl ester (RME) and a superior quality diesel oil according to the Swedish environmentally class 1 (SEC1) were oxidised at 550°C in a reactor. The compounds produced were analysed using a gas chromatographic (GC) method: direct gas injection with GC/MS. Rapeseed oil and RME produced factor 10 more 1-alkenes, dienes, and benzene in comparison with diesel SEC L Rapeseed oil produced high amounts of acrolein and other aldehydes. Oxidation of RME produced significant amounts of methyl acrylate (2-propenoic acid, methyl ester). The different oils produced a varying number of compounds during the oxidation. The rapeseed oil produced 72 peaks with a peak-area above 100 000-area counts and RME produced 61 peaks, in comparison the SEC 1 produced only 27 peaks.

Slow pyrolysis of spruce and pine samples studied with GC/MS and GC/FTIR/FID

Abstract Small samples (10 – 150 mg) from eight pine and spruce species were pyrolysed at 550 °C. The samples were taken from Scotch pine, Austrian pine, Lodgepole pine, Ponderosa pine, Norway spruce, White spruce, Black spruce and Sitka spruce. The compounds produced from the pyrolysis were analysed with several gas chromatographic (GC) methods: direct injection with GC/MS or GC/FTER/FID and pre-concentration with GC/MS and GC/FID. The product distributions of organic compounds from the different conifers show common features. Large amounts of oxygenated organic compounds were formed: aldehydes, acids, ketones and methoxylated phenols. The pine species produced less methoxylated phenols than the spruce species.

Combustion of gasolines in premixed laminar flames European certified and California phase 2 reformulated gasoline.

Two gasoline qualities, European unleaded certified gasoline (EUCG) and California phase 2 reformulated gasoline (P2 RFG), were analysed. EUCG contained about twice the amount of alkyl benzenes compared to P2 RFG and a large amount of cyclohexane. As a balance, P2 RFG contained higher amounts of isooctane and MTBE. The gasolines were burned in a premixed laminar flame burner at 1 atm and at about stoichiometric fuel/air ratio. The species profiles were measured using on-line GC/MS. About 40 compounds were be detected in the gasoline flames. The EUCG resulted in formation of more reactive and toxic compounds. The combustion profiles of the fuel components showed a similar slope, which suggests that the fuel components burn quite independently of each other. Ethene and propene were the dominating species produced from the two gasolines. Commonly, substantial amounts of higher alkenes were found. Combustion of P2 RFG produced higher amounts of isobutene, propene, propyne, propadiene and methanol compared to combustion of EUCG. The high amount of isobutene is reasonably a result of high concentration of isooctane and MTBE in the fuel. The high amount of methanol formed is probably due to the MTBE present in the gasoline. EUCG produced significantly higher amounts of 1,3-butadiene, which quite likely is formed from the cyclohexane in the fuel. The benzene profiles from both gasolines shows an almost constant level up to 800 microm from the burner surface; this is probably due to formation of benzene from alkyl benzenes.

Slow pyrolysis of willow (Salix) studied with GC/MS and GC/FTIR/FID

Abstract Small samples (15–150 mg) of wood and bark from basket willow ( Salix viminalis ) clone Jorr were pyrolysed at 550°C. Samples from pure wood of European White (Silver) Birch ( Betula pendula (alba) ) and Norway Spruce ( Picea abies ) were used as references. The compounds produced during pyrolysis were analysed using gas chromatographic (GC) methods: direct injection with GC/FTIR/FID, direct injection with GC/MS, and pre-concentration with GC/MS. The samples from salix, birch and spruce all produced a range of low molecular weight compounds: aliphatic acids, esters, aldehydes, and ketones as well as furans. Commonly, these samples also formed aromatic compounds: phenol, methyl-phenols, and the guiacol (2-Methoxyphenol) series of compounds. Salix and birch both produced the syringol (2,6-Dimethoxyphenol) series of compounds. Syringol derivatives were not detected from the pyrolysis of spruce.

Slow pyrolysis of birch (Betula) studied with GC/MS and GC/FTIR/FID

Abstract Small samples of wood (15 – 150 mg) from 8 different species of birch ( Betula ) were pyrolysed at 550 °C. The compounds produced from the pyrolysis were analysed using gas chromatographic (GC) methods: direct injection with GC/FTIR/FID and pre-concentration with GC/MS. A broad distribution of oxygenated organic compounds was formed: aldehydes, acids, ketones, substituted furans and methoxylated phenols. The chromatograms were very similar for all eight species, both with direct injection and pre-concentration. Compared to similar studies for pine and spruces significantly higher amounts were formed in the molecular range 60 – 130 amu. The conifers showed more peaks with a molecular weight above 200 amu.

THE CHLORINATING SPECIES IN TURBULENT FLAME COMBUSTION OF METHANE WITH HYDROGEN CHLORIDE PRESENT

Combustion of methane with air in the presence of hydrogen chloride was studied in a turbulent jet-stirred burner. The reaction was monitored by in situ mass spectometry and the ratio of Cl22HCl intensities was measured as a function of equivalence ratio (Φ). For values of Φ = 1.25 − 0.5 (fuel rich to fuel lean flames) the ratio of Cl22HCl intensities was close to zero. For values of Φ < 0.5 the ratio of Cl22HCl intensities increased significantly. The interpretation is that hydrocarbon radicals, e.g. CH, strip Cl from HCl to produce chloromethyl radicals which are known to react to form simple chlorocarbons, chlorinated aromatics, chlorinated PAH and Dioxins. For Φ < 1.0 no chlorination was observed.

Characterization of Combustion Chamber Deposits from a Gasoline Direct Injection SI Engine

Combustion chamber deposits (CCDs) from a gasoline direct injection stratified charge SI engine were analysed. The engine was run with two fuels: a typical European base fuel, containing 9.8% MTBE, and a low volatility worst case fuel. The worst case fuel is a standardized European fuel, CEC RF 86-A-96, prone to form deposits. It contains high amounts of aromatics and olefins but no MTBE. The deposits were analyzed in several ways; thermal desorption followed by gravimetric analysis, fast neutron activation analysis and solid-state 1 3 C nuclear magnetic resonance spectroscopy. Up to 50% of the deposits, formed inside the GDI engine, consist of volatiles. The composition of the deposits is strongly related to the composition of the engine oil. The fraction of volatiles in the deposits decreased in the order: cylinder head, piston squish surface and piston bowl. The deposits from the piston squish surface contained the highest fraction of oxygen, about 30 %. The non-volatile part of the deposits was highly oxidized. The organic oxygen in the non-volatile part was found in different types of carbon compounds: oxygenated aliphatics, carboxyls and carbonyls. The fuels used in this study apparently did not significantly affect the content of oxygen and the volatile organic found in the deposits.