Set Of Oil Samples Research Articles

Determination of Gossypol in Hamid and Bt (Seeni 1) Cottonseed Oil using Fourier Transform Infrared Spectroscopy

This study was conducted to determine the gossypol content in Bt cottonseed (Seeni-1) oil by using Fourier Transform Infrared (FTIR) spectroscopy with an Attenuated Total Reflectance (ATR) element. The wavelengths used were selected by spiking refined, bleached deodorized palm oil (RBDPO) to gossypol concentrations of 0-5% and noting the regions of maximal absorbance. Absorbance values of the wavelength regions 3700-2400 & 1900-750 cm-1 and a partial least squares (PLS) method were used to derive calibration models for Hamid cottonseed oil, Seeni-1 cottonseed oil, and gossypol-spiked RBDPO. The coefficients of determination (R2) for the calibration models were computed for the FTIR spectroscopy results against those found by using the wet chemical method AOCS method Ba 8�78. The R2 was 0.8916, 0.9581, and 0.9374 for Hamid cottonseed oil, Seeni-1 cottonseed oil, and gossypol-spiked RBDPO, respectively. The standard error (SE) of the calibration was 0.053, 0.078, and 0.062, respectively. The calibration models were validated using the cross-validation technique within the same set of oil samples. The results of FTIR spectroscopy as a useful technique determining gossypol content in crude cottonseed oil showed that there is a significant difference (p <0.05) in the amount of gossypol content in Hamid and Bt Seeni-1 cottonseed oils.

THE EVALUATION OF DEEP FRYING OIL QUALITY WITH THE SPECTROPHOTOMETRIC METHOD FOR THE RAPID ASSESSMENT OF TOTAL POLAR COMPOUNDS

This study focuses on the evaluation of official methods for determining frying oil quality with the new spectrophotometric method. The performance of these methods was examined by usage intermittent deep fat frying of potato chips in sunflower oil for 40 hr. at five consecutive days (8 hr., daily). Chemical analysis is the most reliable way to measure decomposition compounds in frying oil. With the prolonged frying time the amount of total polar compounds (TPCs) rises steadily. It has been suggested that the determination of TPCs is the most reliable method for the measurement of oil deterioration during deep frying processes. Beside, other oil quality indices during 40 hr. of intermittent deep fat frying were analyzed by the official methods and/or by rapidly spectrophotometric absorbance methods. Principal component analysis and linear regression analysis were used in order to assess the obtained results. The results were used to calibrate this spectrophotometric absorbance method. There was a strong correlation (r = 0.999) between quick spectrophotometric absorbance values and TPCs content in the same set of oil samples. The equation for conversion of the spectrophotometric absorbance values to TPCs content is: Y = -57.0083 + 2.64X + 0.049 X2. Consequently, spectrophotometric absorbance method was developed to assess deep fat frying oil quality. This study was conducted to examine the relationship of TPCs contents determined by spectrophotometric method with physical, chemical indices and sensory evaluation. TPCs content was found to be correlated with refractive index (r = 0.950), viscosity (r = 0.989), colour (r = 0.993), acid value (r – 0.899), iodine number (r = 0.947), P-anisidine value (r = 0.987), TBA test (r = 0.875), oxidized fatty acids (OFAs) (r = 0.975). Also, TPCs content was correlated with flavour (r - -0.752), greasiness (r - -0.917), crispy texture (r = -0.559) and overall acceptability (r = -0.649).These results showed that the new spectrophotometric absorbance method of frying oil is a good, rapid, simple, convenient and reliable indicator during deep fat frying of sunflower oil tested.

Light Hydrocarbon Geochemistry: Insight into Mississippian Crude Oil Sources from the Anadarko Basin, Oklahoma, USA

The Mississippian limestone is a prolific hydrocarbon play in the northern region of Oklahoma and the southern part of Kansas. The Mississippian reservoirs feature variations in produced fluid chemistry usually explained by different possible source rocks. Such chemical variations are regularly obtained from bulk, molecular, and isotopic characteristics. In this study, we present a new geochemical investigation of gasoline range hydrocarbons, biomarkers, phenols, and diamondoids in crude oils produced from Mississippian carbonate and Woodford Shale formations. A set of oil samples was examined for composition using high-performance gas-chromatography and mass-spectrometry techniques. The result shows a distinct geochemical fingerprint reflected in biomarkers such as the abundance of extended tricyclic terpanes, together with heptane star diagrams, and diamantane isomeric distributions. Such compounds are indicative of the organic matter sources and stages of thermal maturity. Phenolic compounds varied dramatically based on geographic location, with some oil samples being depleted of phenols, while others are intact. Based on crude oil compositions, two possible source rocks were identified including the Woodford Shale and Mississippian mudrocks, with a variable degree of mixing reported. Variations in phenol concentrations reflect reservoir fluid dynamic and water interactions, in which oils with intact phenols are least affected by water-washing conversely and crude oils depleted in phenols attributed to reservoir water-washing. These geochemical parameters shed light into petroleum migration within Devonian-Mississippian petroleum systems and mitigate geological risk in exploring and developing petroleum reservoirs.

UV-Vis Spectroscopy: A New Approach for Assessing the Color Index of Transformer Insulating Oil.

Monitoring the condition of transformer oil is considered to be one of the preventive maintenance measures and it is very critical in ensuring the safety as well as optimal performance of the equipment. Various oil properties and contents in oil can be monitored such as acidity, furanic compounds and color. The current method is used to determine the color index (CI) of transformer oil produces an error of 0.5 in measurement, has high risk of human handling error, additional expense such as sampling and transportations, and limited samples can be measured per day due to safety and health reasons. Therefore, this work proposes the determination of CI of transformer oil using ultraviolet-to-visible (UV-Vis) spectroscopy. Results show a good correlation between the CI of transformer oil and the absorbance spectral responses of oils from 300 nm to 700 nm. Modeled equations were developed to relate the CI of the oil with the cutoff wavelength and absorbance, and with the area under the curve from 360 nm to 600 nm. These equations were verified with another set of oil samples. The equation that describes the relationship between cutoff wavelength, absorbance and CI of the oil shows higher accuracy with root mean square error (RMSE) of 0.1961.

The comparison of naturally weathered oil and artificially photo-degraded oil at the molecular level by a combination of SARA fractionation and FT-ICR MS

Two sets of oil samples, one obtained from different weathering stages of the M/V Hebei Spirit oil spill site and the other prepared by an in vitro photo-degradation experiment, were analyzed and compared at the molecular level by atmospheric pressure photo-ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). For a more detailed comparison at the molecular level, the oil samples were separated into saturate, aromatic, resin, and asphaltene (SARA) fractions before MS analysis. Gravimetric analysis of the SARA fractions revealed a decreased weight percentage of the aromatic fraction and an increased resin fraction in both sets of samples. Molecular-level investigations of the SARA fractions showed a significant reduction in the S1 class in the saturate fraction and increase of S1O1 class compounds with high DBE values in resin fraction. Levels of N1 and N1O1 class compounds resulting in protonated ions (presumably basic nitrogen compounds) increased after degradation compared to compounds generating molecular ions (presumably non-basic nitrogen compounds). This study revealed changes occurring in heteroatom polar species of crude oils such as sulfur and nitrogen containing compounds that have not been easily detected with conventional GC based techniques.

A new method for determining gossypol in cottonseed oil by FTIR spectroscopy

AbstractA new method was developed to determine the gossypol content in cottonseed oil using FTIR spectroscopy with a NaCl transmission cell. The wavelengths used were selected by spiking clean cottonseed oil to gossypol concentrations of 0–5% and noting the regions of maximal absorbance. Transmittance values from the wavelength regions 3600–2520 and 1900–800 cm−1 and a partial least squares (PLS) method were used to derive FTIR spectroscopic calibration models for crude cottonseed, semirefined cottonseed, and gossypol‐spiked cottonseed oils. The coefficients of determination (R2) for the models were computed by comparing the results from the FTIR spectroscopy against those obtained by AOCS method Ba 8‐78. The R2 were 0.9511, 0.9116, and 0.9363 for crude cottonseed, semirefined cottonseed, and gossypol‐spiked cottonseed oils, respectively. The SE of calibration were 0.042, 0.009, and 0.060, respectively. The calibration models were cross‐validated within the same set of oil samples. The SD of the difference for repeatability and accuracy of the FTIR method were better than those for the chemical method. With its speed (ca. 2 min) and ease of data manipulation, FTIR spectroscopy is a useful alternative to standard wet chemical methods for rapid and routine determination of gossypol in process and/or quality control for cottonseed oil.

A performance assessment of source correlation and weathering indices for petroleum hydrocarbons in the environment

AbstractThe source of petroleum contaminants in the environment and the extent to which these contaminants have weathered following deposition can often be determined through an empirical evaluation of oil n‐alkanes, isoprenoids (pristane and phytane), and hopane and sterane biomarkers. Common source correlation and weathering indices have been calculated for three sets of oil samples: fresh, 25% (w/w) weathered, and 50% (w/w) physically weathered diesel standards, crude oils from different sources, and a set of representative heavy oils. For the weathered diesel oils, the C18: tricyclic terpanes and n‐alkanes: tricyclic terpanes indices varied most significantly with diesel weathering. Awareness of this may be important when these indices are used to assess biotic routes of contaminant dissolution. For the crude oil samples, C18: phytane demonstrated low specificity between the oils. C18: 17α(H),21β(H)‐Hopane and n‐alkanes: 17α(H),21 β(H)‐hopane differentiated between crude oils but would be expected to vary significantly during weathering due to the microbial amenability of the alkane numerators. Pristane: phytane, phytane: 17α, 21β‐hopane and tricyclic terpanes: hopanes were considered to be the indices best able to distinguish between oils from different origins, based on these results. 17α(H), 21β(H)‐Hopane: 17α(H), 21β(H)‐norhopane did not adequately distinguish between the respective crude oil samples. Finally, the relationship between heavy oil composition and the index value was investigated. Here, the values of n‐alkanes: 17α(H), 21β(H)‐hopane, phytane: 17α(H), 21β(H)‐hopane, and tricyclic terpanes: hopanes decreased as the combined total of polar and asphaltene compounds within oil samples increased. This relationship may be useful in assessing the degradation status of petroleum wastes.