Petrol Samples Research Articles

Use of optimized 1H selTOCSY for identification and individualization of petrol samples from fire debris

Use of optimized 1H selTOCSY for identification and individualization of petrol samples from fire debris

Individualization of petrol sources by high field nuclear magnetic resonance spectroscopy

In the forensic science context petrol is considered the most common fire accelerant. However, the identification and classification of petrol sources through the years has been proven to be a challenge in the investigation of fire related incidents. This research explored the possibility of identification and classification of petrol sources using high field NMR spectroscopy. In this study, 1H NMR profiling, using specific pulse sequences to analyse neat aliquot petrol samples of different brands collected at different times across the UK and Ireland is shown, for the first time, to provide a diagnostic ‘fingerprint’ with specific chemical compounds that can be used for identification and classification of petrol samples. This enables linkage of unknown petrol samples to a source and in addition provides a tool which allows exclusion of potential petrol sources. A new, innovative method using 1H selTOCSY is described for the individualization and classification of petrol samples through the identification of olefinic markers in the samples. Those markers were identified as (i) 3-methyl-1-butene, (ii) a mixture of 1-pentene and 3-methyl-1-butene, (iii) 2-methyl-2-butene and (iv) a mixture of cis and trans-2-pentene.

Effect of metal catalysis in the electrochemical oxidation of petrol on platinum electrodes and its use in petrol brand fingerprinting

This study presents a novel study to explore the electrocatalytic characteristics of platinum electrodes to obtain the electrocatalytic oxidation of petrol in non–aqueous solutions. A petrol sample was added into an electrochemical cell containing 0.1 M Tetrabutylammonium perchlorate (TBAP) in acetonitrile and studied using cyclic voltammetry and differential pulse voltammetry. The results demonstrated that the metal content in TBAP acted as a catalyst, which effectively interacted with substances present in petrol and formed a new electroactive product, providing an electrochemical oxidation response at + 1.2 V. Inductively coupled Plasma analyses and statistical comparison of different TBAP salt brands, indicated that Calcium, Iron and Manganese were directly response on the catalytic electrooxidation. The electrochemical response of petrol was observed as a diffusion–controlled process on platinum electrode with an irreversible reaction. The electrochemical profiles were used to discriminate different brands of petrol using Principal Component Analysis (PCA). Also, this behavior could be replicated in a simplistic manner using a model solution of Fe+3 and petrol.

Surface-enhanced Raman scattering detection of dibenzothiophene and its derivatives without π acceptor compound using multilayer Ag NPs modified glass fiber paper

Dibenzothiophene (DBT) and its derivatives are important constituents of organosulfur compound in fossil fuels, which can result in one type of “acid rain” after burning process. Several technologies and methods have been developed to detect DBT, but they can be sophisticated and expensive. We have developed a two-step in-situ reduction method to fabricate Ag NPs modified glass fiber paper for SERS detection of DBT and its derivatives in a convenient and cheap way. Different from previous reports showing DBT cannot be detected by SERS, the substrate fabricated by our method revealed DBT's characteristic Raman peak at 1600 cm−1. The dense and multilayer Ag NPs on glass fiber provided abundant spatial surface for DBT absorption and chemical interaction with Ag NPs, which led to CHEM enhancement in SERS detection. The mechanism was verified by UV–visible absorption spectrum and calculated Raman spectra. There was a good linear relationship between the SERS intensity at 1600 cm−1 and the concentration of DBT solution between 1 × 10 −5 and 1 × 10−3 mol/L and the limit of detection was 1 × 10−6 mol/L. Spiked petrol sample was detected and the recovery rate of DBT is in the range of 94.53%–107.39%. This method provides a convenient and reliable way to detect DBT and its derivatives.

Effect of gasoline composition on the absorption and retention of fuel vapor by activated carbon of the automobile adsorber

The physicochemical characteristics of petrol samples are studied. It is established that the fuel purchased at fuel stations corresponds to the standard parameters presented in the EURO standard for unleaded petrol. The presence of saturated hydrocarbons in petrol is determined using concentrated sulfuric acid, which reacts with unsaturated (alkenes, olefins) and aromatic hydrocarbons, without reacting with saturated hydrocarbons. The fractional composition of petrol samples is determined from the distillation temperatures measured by a mercury thermometer included in the automatic oil distillation apparatus ARNS-1E, acidity titration with an alcohol solution of potassium hydroxide gasoline mixtures with 80% ethanol. An acid-base phenolphthalein indicator (pH = 8.0-9.6) is used to indicate an excess of OH−. The density of the fuel samples is measured with oleometers (densimeters), octane numbers (ON) - indicator (Octanometer) OKTAN-IM. The limit of the permissible absolute error of the measurement of ON is ± 2 octane units. It is established that all petrols without exception contain saturated, unsaturated and aromatic hydrocarbons. It is shown that of the seven samples studied, two samples have some peculiarities. It is concluded that when controlling the quality of fuel, it is necessary to take into account not only the conformity of the determined value to the parameter of the norm, but also the differences in the values of the indices obtained when testing a series of fuel samples.

Tracking the origin of fuel oil and petrol in explosive mixtures of ANFO

This research describes the analysis of petrol and diesel from different brands aiming at the identification and classification of ANFO explosives based on gas chromatography − mass spectrometry (GC − MS) and Fourier transform infrared spectroscopy (FTIR) using as an aid principal component analysis (PCA). First, 91 petrol and diesel samples sold in the city of Lincoln (UK) during four seasons (winter, spring, summer, autumn) were analysed by GC − MS and FTIR in order to identify chemical composition and additives with the aim of obtaining a set of potential markers that will allow forensic scientists to identify fuels from different brands. The results demonstrated that each petrol and diesel samples chemically contains unique fuel compositions. MTBE and ETBE were identified as petrol additives that can be used to aid in the separation. The inconsistency in the amount of some petrol compounds, such as isooctane, was also observed and used to establish differences among petrol samples. In diesel, the distribution of FAME contents showed the effect of seasonal variation as these were found less used in winter. The selection of a reduced number of key fuel compounds and additives was also shown to be sufficient to allow a classification among the different fuel samples with a high accuracy (from 80–100%) using PCA-LDA. Second, the classification of pre-blast ANFO explosives are excellently achieved using GC − MS and FTIR. Diesel can be extracted from ANFO mixtures and analysed by GC − MS. The chromatographic pattern of each extraction sample exhibited the characteristic peaks of FAME contents in some samples. PCA is effectively used to classify all diesel extracts. The selection in the specific diesel components considerably showed an effect to the classification among diesel samples and significantly provides different degree of discrimination of the ANFO samples. In addition, the use of mid − infrared spectral region combined with PCA and leave-one-out cross-validation is effectively able to discriminate different ANFO samples with high classification performance. Unfortunately, the determination and classification of ANFO from post blast samples was not successfully achieved.

The Use Of Chemical Composition And Additives To Classify Petrol And Diesel Using Gas Chromatography–Mass Spectrometry And Chemometric Analysis: A Uk Study

AbstractThe identification of the fuel found in a crime scene and establishing its source is important for forensic investigations. In this study petrol and diesel samples were analysed in order to identify chemical composition and additives with the aim of obtaining a set of markers or compounds that will allow forensic scientists to identify fuel sources. The study was performed using petrol and diesel sold in the city of Lincoln (UK) during four seasons (winter, spring, summer, autumn).Diesel samples, representing eight different brands were analyzed by gas chromatography−mass spectrometry (GC−MS) and principal component analysis (PCA). From the GC–MS analytical results, MTBE and ETBE were identified as the additive more preferably added in super unleaded petrol samples that can be used to aid in separation and identification. In diesel, the distribution of FAME contents showed the effect of seasonal variation as these were found in all spring, summer and autumn samples, but not found in all winter ones. The selection of a reduced number of key fuel compounds and additives was also shown to be sufficient to achieve a high level of classification among the different fuel samples. Leave–one–out cross–validation was applied in order to validate the results.

Single channel photonic crystal fiber based high sensitive petrol adulteration detection sensor

A dual core photonic crystal fiber (DCPCF) consisting single analyte channel is proposed in this article for the detection of petrol adulteration. The sensing probe is numerically studied using finite element method. The adulterated petrol sample is infiltrated in circular analyte channel which is situated at the center of the fiber between two solid light guiding cores. The mode coupling between these two cores as well as sensitivity of the designed probe are investigated by varying adulteration level of petrol. Also the structure is optimized step by step. The numerical simulation result shows very high sensitivity of 20,161.2 nm/RIU for practically usable small probe. A portable adulteration detection sensor can be manufactured using this simple structured DCPCF probe which will be useful to study environmental pollution, maintaining long engine lifetime, save revenue.

LSSVM Combined with SPA Applied to Near-Infrared Quantitative Determination of the Octane in Fuel Petrol Samples

Least square support vector machine (LSSVM) combined with successive projection algorithm (SPA) method was applied for near-infrared (NIR) quantitative determination of the octane number in fuel petrol. The NIR spectra of 87 fuel petrol samples were scanned for model establishment and optimization. First order derivative Savitzky-Golay smoother (1st-d’SG) was utilized to improve the NIR predictive ability. Its pretreatment effect was compared with the raw data. SPA was applied for the extraction of informative wavelengths. Considering the linear and non-linear training mechanism, LSSVM regression was employed to establish calibration models. The correlation coefficient (R) and root mean square error (RMSE) were used as the model evaluation indices; accordingly the octane number in fuel petrol was quantitatively determined with the prospective predictive indices. Results showed that after pretreated by 1st-d’SG, 8 SPA-selected wavelengths was generated as the inputs of LSSVM, so that the calibration models were optimized in the way of combining the SPA-LSSVM regression with the SG smoother. The prediction results were quite satisfactory, with the calibrating correlation coefficient of 0.951 and the RMSE of 3.282. An independent testing sample set was used to evaluate the optimal model, the testing correlation coefficient was 0.903 and the RMSE was 4.128. We conclude that NIR spectrometry is feasible to determine the octane in fuel petrol by establishing SPA-LSSVM models. The 1st-d’SG pretreatment has the advantage of selecting wavelengths containing the implicit information. The combination of 1st-d’SG pretreatment and SPA-LSSVM show its applicable potential to predict the octane number in fuel petrol.

Effect of Rust & Free Water on Flash Point of Diesel and Petrol Samples

Effect of Rust & Free Water on Flash Point of Diesel and Petrol Samples

Monitoring fuel quality: a case study for quinizarin marker content of unleaded petrol marketed in Greece

Fuel adulteration and cross-contamination lead to low-quality fuel products, which may cause increased environmental pollution, loss of taxes and engine problems. An establishment of a quality monitoring mechanism based on laboratory measurements may reveal problematic areas of the fuel supply chain. For the purposes of this work, 97 unleaded petrol samples were measured in order to quantify mass concentration of quinizarin, a substance used in Greece to easily mark the presence of 95 Research Octane Number unleaded petrol in other types of automotive fuels. The samples were obtained from petroleum retail stations selling different brands of fuels and located in different geographic regions of Greece. Statistical analysis of the results revealed quinizarin mass concentrations below the 3 mg L−1 legislation specification limit and significant differences between brands and geographic regions, which may attributed to the structure of the fuel supply chain in Greece in combination with quinizarin properties and way of handling. Moreover, certain approaches were used for the calculation of decision limits for assessing compliance or non-compliance. These approaches take measurement reproducibility or estimated in-house uncertainty into account, in order to minimize the probability of false rejection.

A Method to Detect the Mixed Petrol Interface by Refractive Index Measurement With a Fiber-Optic SPR Sensor

A method based on fiber-optic surface plasmon resonance (FO-SPR) to detect mixed petrol is proposed to realize real-time, rapid monitoring of the mixed petrol interface in transportation pipelines. When the sensing region of the FO-SPR sensor was immersed in the petrol sample, the mixed petrol could be detected by measuring the refractive index of the petrol, which responds to the resonance wavelength in the SPR curve. Numerical simulation was performed according to the optical fiber theory and the SPR principle to optimize the structural parameters of the sensor. The optimized sensor can reflect small changes of the refractive index for mixed petrol detection. Next, the end-reflection FO-SPR sensor was designed and fabricated. The fiber was rotated in addition to the revolution of the coating disc to realize a uniform coating of the circumferential surface of the fiber core during vacuum coating. A wavelength modulation optical measurement system with the FO-SPR sensor was constructed. Petrol 90#, Petrol 93#, Petrol 97#, and their mixtures were measured. The experimental results indicated that this method could detect different mixing ratios of petrol with good repeatability, which lays the technical foundation for fast and accurate online detection of the mixed petrol interface in transportation pipelines.

An assessment of petrol fire risk by oxygen consumption calorimetry

This article evaluates the fire risk of petrol utilising a novel testing procedure that enables the measurement of heat release rate (HRR), specific mass loss rate and carbon monoxide (CO) yield of flammable liquids in a cone calorimeter. The testing procedure is a modification of the procedure described in ISO 5660-1:2002. The modification includes the use of a sample pool enabling the testing of flammable liquids. Pure petrol samples were tested. They were ignited with a spark igniter, without the use of a cone heater. The cone heater was removed before testing to avoid its heating by the flame and consequent heat radiation onto the tested sample surface. The average HRR was 612 kW m−2 and the maximum HRR was 842 kW m−2. The total CO yield related to mass loss was 58.6 g kg−1 and related to the effective heat of combustion was 1.48 g MJ−1. The immediate CO yield increased significantly with an increase in testing time (an increase in the depth level of liquid below the upper edge of the pool). Dependence equations of HRR and specific CO production rate (SCPR) on the specific mass loss rate were calculated from the obtained data. Substituting the specific mass loss rate of petrol (55 g m−2), which burns in an infinite diameter pool, the HRR (1,581 kW m−2) and SCPR (3.99 g m−2 s−1) were calculated for petrol pool fire under real conditions (at pool diameter larger than 1.5 m). The calculated SCPR accounted for a CO yield of 72.55 g kg−1.

The preparation, properties and application of carbon fibers for SPME

The conditions of preparation of new types of carbon fibers for solid phase micro extraction (SPME) prepared by methylene chloride pyrolysis (at 600 °C) on the quartz fiber (100 μm) as well as by supporting synthetic active carbon (prepared especially for this purposes) supported in a special epoxide-acrylic polymer is described. The properties of such carbon fibers for SPME were defined by determination of the partition coefficient of the tested substances (i.e., benzene, toluene, xylenes, trichloromethane and tetrachloromethane) and by the microscopic investigations with the application of the optical and scanning electron microscope. The obtained carbon SPME fibers were applied to the analysis of some volatile organic compounds from its aqueous matrix. During chromatographic GC test, at the investigated SPME carbon fibers, we obtained different but mostly high partition coefficients for the determined compounds (Kfs from 120 for trichloromethane up to 11,500 for tetrachloromethane). Owing to the high partition coefficients of the studied substances obtained on carbon fibers, it was possible to do the analysis of organic substances occurring in trace amounts in different matrices. In this paper, we present the analysis of BTX contents in the petrol analyzed with the application carbonized with CH 2Cl 2 SPME fiber (C1NM) and a headspace over the petrol sample (concentration of each BTX ∼g/dm 3).

Luminescent Determination of Automobile Petrol in Hexane Solutions

The work deals with the problem of determination of automobile petrol of various octane numbers and petroleum contamination of some objects on the basis of analysis of photoluminescence spectra of automobile petrol samples. For this purpose steady state luminescence properties of samples of automobile petrol of different types being in sale were measured. Samples of automobile petrol diluted in hexane were prepared and their luminescence spectra were measured at room and liquid nitrogen temperatures of samples. We constructed concentration dependences of luminescence intensity of both wide band luminescence of liquid solutions obtained at room temperature and peak intensities of luminescence lines of quasi linear spectra of solutions frozen at 77 K. Possibility to use luminescence method for analysis of petrol pollutions on some objects is illustrated by results of investigation of pine-wood pieces contaminated by automobile petrol.

Benzene emission from the actual car fleet in relation to petrol composition in Denmark

The present study covers an investigation of the trends in air pollution levels of benzene in Danish cities and their relationship with the benzene content in petrol. Petrol samples from the two refineries in Denmark as well as sold petrol from some representative Danish petrol stations were analysed. The benzene content in Danish petrol was reduced from 3.5% for 95 octane prior to 1995 to approx. 2% in 1995 and further to 1 % in 1998. Air quality measurements of aromatic VOC are available from two Danish cities; Copenhagen since 1994 and Odense since 1997. Measurements of benzene, CO and NO x from these two locations were analysed using the Operational Street Pollution Model (OSPM) and trends in the actual emissions of these pollutants were determined. It is shown that the decrease in both the concentration levels and in the emissions was significantly larger for benzene than for CO and NO x . The decreasing trends of NO x and CO could be explained by the increasing fraction of petrol-fuelled vehicles with three way catalysts (TWC). The much steeper decreasing trend for benzene can most likely be attributed to a combination of the effect of the increasing share of the TWC vehicles and a simultaneous reduction of benzene content in Danish petrol. The reduction of benzene concentrations and emissions is observed despite that the total amount of aromatics in petrol has increased slightly in the same period.

Sono-Electroanalysis: Application to the Detection of Lead in Petrol

The quantitative detection of lead in petrol is shown to be possible by anodic stripping voltammetry in aqueous media under conditions of insonation-induced emulsification. An immersion horn probe is introduced into a thermostatted conventional three-electrode cell opposite a mercury plated platinum disk working electrode. Under ultrasonic emulsification of the sample, lead is preconcentrated as an amalgam on the Hg/Pt electrode surface via reduction at –1.0 V (vs. SCE). The large mass transport associated with power ultrasound makes this step highly efficient. Subsequently the lead is quantified by applying an anodic linear sweep of the potential from –1.0 V to –0.15 V (vs. SCE) so as to oxidize the Pb(0) to Pb(II). The area under the stripping peak gives a measure of the lead formed during the initial step. By use of standard microaddition of lead to the solution the system can be calibrated to give the total amount of lead present in the petrol sample. Experiments using samples of 4 star leaded petrol gave a total lead content of 380±40 mgL–1. This value was in quantitative agreement with that obtained by an independent laboratory using atomic absorption spectroscopy (AAS). In addition to the high mass transport and emulsification insonation offers the crucial benefits of first surface activation and cleaning, helping to prevent electrode fouling by the organic components of petrol and second the complete extraction of lead from the water-insoluble target phase.

Simultaneous flow analysis Fourier transform infrared determination of benzene, toluene, and methyl t-butyl ether in petrol

A new procedure has been developed for the simultaneous flow analysis Fourier transform infrared (FTIR) determination of benzene, toluene and methyl t-butyl ether (MTBE) in real petrol samples. The method is based on the dilution of samples in hexane (1 + 9) and direct injection of 300 µl of the diluted samples into a 0.28 ml min–1 carrier flow of hexane. First-order derivative absorbance measurements are carried out by FTIR, in the wavenumber range 1350–400 cm–1. The three compounds studied were determined simultaneously in the same sample without additional sample preparation. Benzene was determined by measurement of the first order derivative (dA/d, where A is the absorbance, and , the wavenumber) between the peak at 678 cm–1 and the valley at 672 cm–1 with a dynamic range between 0.005 and 0.8% v/v, being established as the limit of detection for a probability level of 99.6%. Toluene was determined by measuring dA/d between 731 and 725 cm–1, the dynamic range being from 0.01 to 2.0% v/v. Methyl t-butyl ether was determined by measuring dA/d between 1209 and 1201 cm–1, providing a dynamic range between 0.035 and 2% v/v. The method can be applied to the direct analysis of petrol; the results obtained in the determination of the three compounds in real samples agree with those found by gas chromatography.