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Cetane number is a prime indicator in evaluating the quality of biodiesel fuel in the realm of diesel engines. Standards have been established world wide for cetane number determination, for example ,ASTM D 613 in the USA, internationally, the International Organization for Standardization (ISO) standard ISO 5165, etc. These methods are usually arduous and expensive; the values obtained are mostly subjected to some experimental error. Four biodiesels are considered as reference fuel for present investigation. Data are collected from the literature on the cetane number, physical properties and the FAME compositions of various biodiesel fuels. Initially, the cetane index is calculated by ASTM D 976 and ASTM D 4737, compared with the standard literature values for the reference biodiesels. The regression equations are developed for predicting the cetane number from their physical properties and FAME compositions. Finally, comparative study is made to suggest better options among the methodologies under study.

The passage of the revised Clean Air Act Amendments on November 15, 1990 and recent EPA regulations will result in landmark changes in the major transportation fuels in the United States. There could be significant changes in the compositions of both gasoline and diesel fuels based on recipe formulation or performance standards designed to meet both environmental considerations and quality requirements. For gasoline, the major changes might include adding oxygenates, reducing total aromatic as well as benzene concentration, and lowering the Reid vapor pressure (RVP). The next-generation diesel fuel must conform to the lower sulfur content and possibly higher cetane index specifications. This paper discusses various process technologies and refinery configurations that could be required to produce tomorrow’s fuels.

The impact on exhaust emissions of diesel fuel composition was studied by a comprehensive program compiled after discussions with the oil industry, the motor vehicle manufacturers and the Swedish Environmental Protection Agency. In order to reduce the emissions from diesel fueled vehicles different possibilities have to be taken into consideration such as improvement of the engine, use of exhaust purification devices and use of diesel fuels of improved quality. The aim of this investigation was to study the connection between certain fuel parameters and exhaust emissions. Eight different diesel fuels were used in the investigation and the emission tests were carried out using a city bus and a truck, driven on a chassis dynamometer. Both regulated andunregulated emissions were measured. In addition to the emission measurements samples were taken and prepared for biological testing. The investigation showed that there is a clear correlation between certain fuel parameters and the emissions and biological activity of the exhaust. Multivariate analysis was undertaken on groups of data derived from the eight blends of fuels in order to study the correlation between the fuel and emission parameters. A least square regression analysis of the correlation between 23 fuel parameters and 43 exhaust emission parameters resulted in correlation coefficients, which were higher than 0.95 for the two vehicles tested. It was confirmed that the most important fuel parameters to be controlled are the density, boiling point range, the content of aromatics and cetane index. In addition to these parameters the content of polycyclic aromatic hydrocarbons should be controlled and limited. Sulfur is also an important parameter to be controlled especially when the fuel is going to be used for vehicles equipped with catalysts or catalytically activated particulate filters.

Several diesel identified as having significant effects on diesel engine emissions. This paper reports, for heavy-duty diesel engines, fuel properties of aromatics, back end volatility (represented by the 90 percent boiling point), and sulfur examined in a previous CRC VE-1 study in which reductions in all three properties decreased regulated emissions to varying degrees. Aromatic levels and cetane numbers were generally correlated in the previous study, so variation in emissions due to aromatics could not clearly be assigned to variation in aromatic levels alone. To separate the effects of aromatics and cetane number, a fuel set with controlled variation in aromatics and cetane number was developed, including the use of ignition improver to increase the cetane number of selected fuels. The fuel set was used in a 1991 Prototype DDC Series 60 heavy-duty diesel engine to examine regulated emissions over EPA transient cycle operation. Results indicate that cetane number was the key fuel property affecting transient HC and CO emissions. In addition, cetane number was the principal fuel property affecting composite particulate emissions, but aromatic effects were also significant. For emissions of NO{sub x} both cetane number and aromatics were significant for transient emissions.

Since worldwide conversion processes are used to upgrade heavy oil to distillates, the hydrotreatment of light gas oil (LGO) as a downstream process has been used more extensively. This fraction (LGO) is produced from thermal or catalytic cracking or hydrocracking processes. It contains high amounts of unsaturates, nitrogen, and sulfur compounds which cause instability while in storage due to gum formation. The use of LGO as a fuel oil for diesel engines plugs the filter and produces sulfur and nitrogen emissions. These sulfur and nitrogen compounds arise from the cracking of heavy cuts and are aromatic-type molecules which are difficult to hydrogenate. This cut also possesses a low cetane index (CI) which must be increased (by aromatic hydrogenation) because of its poor motor performance. Color and color stability are associated with a high bromine number (BN, unsaturated content), nitrogen, and aromatic content. In order to improve these properties, a deep hydrogenation is sometimes required.

In nickel-exchanged NaY for the oligomerization of ethene at 3500 kPa, catalyst activity and selectivity correlates with the degree of ion exchange, which was varied between 10 and 40%. The catalysts show two regions of high activity, one at a low temperature (l00-150°C) and one at a high temperature (>300°C). At low temperatures, the oligomerization proceeds by a selective growth reaction following Schulz-Flory statistics and, at an mass hourly space velocity of 2 h-1, 26% C10+ product is obtainable in a straight run. At high temperatures, acid-catalysed site reactions contribute to the product spectrum. The Calculated Cetane Index (CCI) was taken as a first indication of the diesel quality obtained at a low temperature. Despite a low cut-off point, a CC1 of 46 was found for a partially hydrogenated sample. It is suggested that different active surface compounds are responsible for the catalyst activity at low and at high temperatures.

A range of 18 diesel fuels and 21 kerosene fuels from mainly Australian petroleum and synthetic fuel sources, including coal, shale and peat, was investigated. Compositional details were defined as the weight per cent abundances of n -alkanes, branched plus cyclic saturates, single-ring aromatics, doublering aromatics and polynuclear aromatics, using both h.p.l.c. and 13 C n.m.r. techniques. Relationships between fuel composition and a range of fuel properties were sought. Simple linear relationships between property values and compositional data were used. Explicit correlative expressions were derived using multiple linear regression analysis, with the coefficient of multiple determination, R 2 , indicating the quality of the fit between observed and calculated property values. In most cases good correlations were achieved. For diesels the properties investigated, with R 2 values in parentheses, were: inverse specific gravity (0.99); 13 C n.m.r. aromaticity (0.99); 1 H n.m.r. aromaticity (0.88); cetane index (0.97); aniline point (0.96); diesel index (0.98); and FIA-measured aromatics content (0.77). For kerosenes the properties, with R 2 values in parentheses, were: 13 C n.m.r. aromaticity (0.98); 1 H n.m.r. aromaticity (0.97); smoke point (0.88); and FIA-measured aromatics content (0.94). The results are shown to be of value in assessing the potential and limitations of hydrotreating as a process for upgrading synfuels.

炭化水素のセタン価を推測するための混合セタン価の妥当性を調べ, 20種類の炭化水素のセタン価を測定した。6種類の炭化水素の混合セタン価が, その実測セタン価と一致することを確かめ, これに基づいて14種類の炭化水素の混合セタン価を求めた。合計20種類の各炭化水素の化学構造とセタン価の関係は, ディーゼル燃料の炭化水素組成とセタン価の関係について公知の傾向と一致していることを認めた。混合セタン価法は, より広範囲な純炭化水素類のセタン価の推測を可能にするため, 炭化水素の化学構造とセタン価の基礎的な関係を調べるうえで有効な手法であることを示した。

The hydrotreatment of heavy gas oil derived from Athabasca bitumen was studied in a trickle bed reactor over Ni-Mo, Ni-W, and Co-Mo supported on alumina catalysts at 350/sup 0/C and 4.24-12.51 MPa. The effects of temperature, pressure, and liquid flow rates on the product were investigated. ASTM distillation, cetane index, aniline point, diesel index, C/H atomic ratio, viscosities, and densities of the product were measured and correlated with various parameters. The activities of the catalysts for hydrodenitrogenation (HDN) and hydrodesulfurization (HDS) are compared. While Ni-W/Al/sub 2/O/sub 3/ was best for cracking, hydrogenation, and hydrodesulfurization, Ni-Mo/Al/sub 2/O/sub 3/ was best for hydrodenitrogenation.

A group property approach has been developed to predict 17 physical properties of middle distillate (e.g., jet and diesel) fuels from experimentally derived liquid chromatography//sup 1/H nuclear magnetic resonance (LC//sup 1/H NMR) data. In the LC//sup 1/H NMR technique, the fuel is separated according to chemical class and the average molecular structure for each chemical class is then calculated. These average molecular structures form a basis set to predict the physical properties of the fuel. The physical properties that can be obtained in this manner are cetane number, cetane index, density, specific gravity, pour point, flash point, viscosity, filterability, heat of combustion, cloud point, volume percent aromatics, residual carbon content, and the initial, 10%, 50%, 90%, and end boiling points. Fourteen of the correlation coefficients for the predictions are better than 0.90 with 11 of the predictions falling either within or approximately equal to the ASTM method reproducibility for the measurement of the fuel property. The present method also provides chemical insight concerning the influence of chemical structural changes on the physical properties of the fuel as well as requiring much less analysis time and sample volume than corresponding ASTM methods.

Chemical and physical characteristics of some compression-ignition fuels derived from vegetable oils are recorded and some relationships between them established. From consideration of the literature relating to spark-ignition engine performance and its dependence upon hydrocarbon fuel structure, guidelines are proposed for the chemical structure requirements of compression-ignition engine fuels derived from plant seed oils. The guidelines have proved successful in predicting the ignition quality of a range of vegetable oil fuels evaluated by means of a rapid ranking engine test method and have been further supported by cetane index calculations (carried out according to ASTM standard method D976) and by other recently published data.

ジーゼル燃料のセタン価測定用正標準燃料セタンは従来輸入に俟つたが, これを国産化するため種々の研究を行つた結果, 高級脂肪酸およびそのエステルを原料として高圧水素還元を行う場合, 原脂肪酸と同数の炭素康子数を有する炭化水素を与える触媒として, 三硫化モリブデンが最適なることを確認した。鯨蝋を原料として反応温度, 触媒の添加量など反応條件のセタン価に及ぼす影響を明らかにした。鯨蝋の成分はバルミチン酸セチルエステルなのでセタン製造原料として好適と思われたが, 長連鎖のため側鎖反応を件い易く, 純セタンは好收量では得られなかつた。しかしセタン価100のものを好收量で得られたので, セタン価100副標準燃料として工業化し得た。さらに動植物天然油脂, 抹香鯨脳油, 大豆油, 米糠油, 木蝋などの水添油からもセタン価100のものを得たので, これらの結果について報告する。

This work deals with obtaining models for predicting the cetane number and ignition delay using artificial neural networks. Models for the estimation of the cetane number of biodiesel from their methyl ester composition and ignition delay of palm oil and rapeseed biodiesel using artificial neural networks were obtained. For the prediction of the cetane number model, 38 biodiesel fuels and 10 pure fatty acid methyl esters from the available literature were given as inputs. The best neural network for predicting the cetane number was a conjugate gradient descend (11:4:1) showing 96.3% of correlation for the validation data and a mean absolute error of 1.6. The proposed network is useful for prediction of the cetane number of biodiesel in a wide range of composition but keeping the percent of total unsaturations lower than 80%. The model for prediction of the ignition delay was developed from 5 inputs: cetane number, engine speed, equivalence ratio, mean pressure and temperature. The results showed that the neural network corresponding to a topology (5:2:1) with a back propagation algorithm gave the best prediction of the ignition delay. The correlation coefficient and the mean absolute error were 97.2% and 0.03 respectively. The models developed to predict cetane number and ignition delay using artificial neural networks showed higher accuracy than 95%. Hence, the ANN models developed can be used for the prediction of cetane number and ignition delay of biodiesel.

Partial least squares regression (PLS) was used to predict flash point and cetane index of diesel using distillation curves (ASTM-D86). The low RMSEP values obtained, compared with other chemometric models based on spectrometric methods described in literature, and high correlation coefficients between reference and predicted values showed that PLS was efficient to determine flash point and cetane index. The model built contains diesel samples of different compositions, thus revealing the variety of fuel in the Brazilian market. Furthermore, the proposed method has two advantages: low cost and easy implementation, as it applies the results of a routine test to evaluate the quality of diesel.

Cetane indexes have been calculated for the esters of the individual saturated fatty acids in the C8-C24 range plus palmitoleic, oleic, linoleic, and linolenic acids. Two methods were used for these calculations: ASTM 976 and a method involving simultaneous equations relating the experimentally determined cetane numbers for several transesterified oils and the fatty acid compositions of the oils. Cetane indexes calculated according to ASTM 976 produced values which were too low for ester mixtures high in saturated acids and low in polyunsaturated acids, and were somewhat high for ester mixtures high in polyunsaturated acids. When cetane indexes calculated according to the simultaneous equation method were applied to the fatty acid mixtures, the agreement with those experimentally determined was approximately the error of determination of the cetane number.

高速ディーゼル燃料に規定されているセタン指数の実用化を計るために, これを図示化した.JIS規格K-2204に示されている計算式と本図との問には, セタン指数で最大±0.2以下の偏差をもつて一致する.しかし各種ベースの軽油について調べた結果, セタン指数はセタン価実測値と数字的に最大±2以下の偏差があるため, これを取引売買する際発火性をセタン指数で代替する場合には十分検討して決めなければならない。

This work presents the physical–chemical properties of fuel blends of waste cooking oil biodiesel or castor oil biodiesel with diesel oil. The properties evaluated were fuel density, kinematic viscosity, cetane index, distillation temperatures, and sulfur content, measured according to standard test methods. The results were analyzed based on present specifications for biodiesel fuel in Brazil, Europe, and USA. Fuel density and viscosity were increased with increasing biodiesel concentration, while fuel sulfur content was reduced. Cetane index is decreased with high biodiesel content in diesel oil. The biodiesel blends distillation temperatures T 10 and T 50 are higher than those of diesel oil, while the distillation temperature T 90 is lower. A brief discussion on the possible effects of fuel property variation with biodiesel concentration on engine performance and exhaust emissions is presented. The maximum biodiesel concentration in diesel oil that meets the required characteristics for internal combustion engine application is evaluated, based on the results obtained.

This chapter describes the use of cetane numbers for diesel fuels. Cetane numbers are used to indicate the quality of a fuel oil for compression–ignition engines. The straight-chain hydrocarbon cetane C 16 H 34 is perhaps the best high-speed diesel fuel known and is given a rating of 100. Aromatic hydrocarbons are poor diesel fuels, and the aromatic hydrocarbon methyl-naphthalene is given a rating of 0. The cetane number of diesel oil is the percentage by volume of cetane in a cetane/methyl naphthalene mixture that has the same performance in a standard compression ignition engine as that of the fuel. An alternative method of expressing the quality of diesel oils is by use of the Diesel Index, which does not necessitate the use of a test engine. Aniline Point is the lowest temperature at which the oil is completely miscible with an equal volume of aniline. For a good-quality diesel oil, the aniline point is >22°C.

The combustion emissions from mobile sources, including both gases and particles, are very complex and may have thousands of separate components. Qualitative and quantitative identification of all of these individual components is a tremendous task. The analytical challenge is facilitated if the number of compounds requiring identification can be reduced.

The complexity of and expense involved in determining the cetane number of diesel fuels using a standard test engine have led to the development and widespread use of the ASTM cetane index. However the cetane index was not intended for use with alternative or unusual diesel fuels; its use with such fuels can lead to large errors. Using a database of alternative diesel fuel properties, a new cetane number prediction equation has been developed for use with alternative fuels, including alcohols. Compared with the cetane index, the average error in predicted cetane number is reduced by 40% and the number of cases where the error exceeds 5 cetane numbers is reduced by 30%. The significance of the various terms in the equation is discussed.

The results for the cetane engine tests showed a strong correlation between cetane number and ignition delay for all fuels tested. Also, a higher cetane number was generally reflected in better engine performance, emissions, and heat release results in the cetane engine. Comparison of test results with data from another program indicated that there were similarities between the cetane engine and an IDI engine but correlation with a DI engine was poor. Conclusions are that revised instrumentation and carefully controlled test procedures can yield consistent results from the cetane engine, however, a strong correlation between these results and the performance of a given fuel in modern design DI and IDI engines has not been established.

Detailed analysis was performed on the Cetane Scale used to rate the auto ignition quality of fuels; the effect of an increase in temperature and pressure, due to increasing the compression ratio, on ignition delay was theoretically and experimentally evaluated. The CFR cetane variable compression engine used in the investigation had a combustion chamber divided into two parts connected by a passage tangential to the prechamber. Cylinder gas pressure, injector needle lift, fuel line pressure, fuel flow rate, air flow rate, intake air heater performance, and intake air surge tank performance were measured. Experimental work was conducted in four phases: engine certification; analysis of cetane number auto ignition parameters; techniques to modify the Cetan Scale to rate low ignition quality fuels; and comparison between fuel ratings on 150-degree F and 350-degree F scales. Results showed ignition delay was more sensitive to air temperature than air pressure. Sensitivity increased with a drop in fuel cetane number. A modified cetane scale was developed by raising the inlet temperature from 150 to 350 degrees F without changing the rest of the rating technique; this extended the scale to zero cetane number and enabled the rating of low ignition quality fuels. Increasing intake air temperature was effective in reducing the compression ratio required to rate low ignition quality fuels. The cycle-to-cycle variation in the length of the ignition delay decreased with a raise in intake air temperature. Fuel blends with low cetane numbers exhibited sensitivity and resulted in lower cetane ratings at higher inlet temperatures. It is recommended that a study be made of the factors affecting the cycle-to-cycle variation in the length of ignition delay of low ignition quality fuels (e.g. gasoline fuels), of cetane scales at intake temperatures other than 350 degrees F, and of the problem of fuel sensitivity of low ignition quality fuels when the intake temperature is increased. Engine specifications and information on the computer model for the compression process in the CFR cetane engine are appended.

Diesel engines have to face the prospect of running on heavy and/or low cetane fuels in the future because of the expected changes in base stock and demand. The effect of physical properties and composition of fuels on the ignition delay and cetane rating is examined. The experiments were conducted on fuels having a very wide range of physical properties and C.N., in a CFR engine. The ignition delay is measured under the standard ASTM D-613 procedure and under varying needle opening pressures, and coolant temperatures. The ignition delay of some fuels is found to be dependent on the physical properties and composition of the fuels in addition to the cetane number. The cetane rating according to ASTM-D613 procedure is found to take place under hot engine conditions with a single stage ignition process. At lower compression ratios, a two stage ignition was observed. A correlation between cetane number and fuel composition was derived and found to be in agreement with the experimental results.

Three new predictive equations for cetane number have been developed. Each of these equations is shown to be superior to the current cetane index equation (ASTM D976-80) for a large fuel data base. One of the equations has the further advantage of requiring only one property measurement (aniline point). The equations were developed from a detailed analysis of functional relationships between measured cetane number (ASTM D613-84) and commonly measured physical properties of diesel fuels; aniline point, density, and distillation temperatures. The data base for this study totaled 1229 fuels, including commercial fuels from the U.S. Canada, Europe, and Japan; synthetic fuels derived from tar sands, shale, and coal; and a diversity of research fuels blended from straight-run and cracked stocks. The equations were optimized using data-fitting techniques which account for bias amongst the various data sources and for measurement errors in both the dependent and independent variables.

Through the extensive R&D effort for heavy oil upgrading technology in Japan Petroleum Cooperation Center, Petroleum (JCCP) since 1993, a zeolite-based new catalyst for atmospheric resid (AR) hydrocracking was developed. Its production in industrial scale was successfully accomplished, and its high and stable performance as resid hydrocracking catalyst in Atmospheric Resid Desulfurization (ARDS) unit was confirmed in bench plant using Kuwait atmospheric resid (Kw-AR) as feed. Namely, toward 2600 h of duration, AR conversion and middle distillate yield were stable at 47% and 30 wt%, respectively, and products quality was excellent, such as cetane index of diesel fraction was very high, as high as 56, and its sulfur content was about 30 ppm, which was by far the lower compared to conventional ARDS unit.

Chemical and thermal analyses were carried out on degummed and filtered (5 µm) rapeseed oil (referred to as SRO, i.e., semirefined rapeseed oil) to determine its suitability as a diesel fuel extender. The upper rate for inclusion of SRO with diesel fuel is 25%. This fuel blend had a phosphorus level of 2.5 ppm, which was comparable to rape methyl esters (1.0 ppm phosphorus). Thermogravimetric analyses were used to estimate the cetane ratings of the fuels. A 25% SRO/diesel blend had an estimated cetane index of 32.4 compared to 38.1 for diesel fuel only. Differential scanning calorimetry and thermogravimetric analyses were used to compare the volatility ranges of the fuels. SRO needed higher temperatures for volatilization (i.e., 70–260°C for diesel fuel vs. 280–520°C for SRO). This indicated poorer cold-starting performance of SRO compared with diesel fuel. SRO fuel is a low-sulfur, high-oxygen fuel giving SRO a more favorable emissions profile than pure diesel fuel.

Biohydro-fined diesel (BHD) is the second generation Biodiesel (BOD) which is also carbon neutral biomass fuel more effective in CO 2 reduction. The quality of BHD is same as conventional petro diesel fuel; therefore, BHD can be used without any modification of infrastructures and vehicles. Vegetable oil has boiling point of around 600 °C and not suitable for diesel engine motor vehicles. But the vegetable oils are hydrogenated by carrying out the Biohydrogenation or Biohydro-fining process resulting in hydrocarbon nearly equal to petro diesel called BHD. In the hydrogenating process, vegetable oils are decomposed down to a molecular weight equivalent to the components contained in diesel fuel, and unsaturated hydrocarbons contained in vegetable oil are converted to saturated hydrocarbons. In the hydrogenation reaction of vegetable oil, it is observed that, in conditions in which complete hydrogenation of the unsaturated bonds is reached; the complete hydrodeoxygenation of the oil was also reached. Moreover, hydrodeoxygenation reactions include a dehydration reaction in which oxygen is eliminated as water (H 2 O), and a decarbonation reaction in which oxygen is eliminated as carbon dioxide (CO 2 ), both reactions were occurring in this processing. To eliminate a given quantity of oxygen, less hydrogen is consumed in decarbonation than in dehydration. At such time when, through optimization of reaction conditions and catalysts, it becomes possible to control the hydrogenation reaction, one should select a reaction system based on which is best overall with respect to issues of hydrogen consumption, byproducts, and LCA CO 2 . BOD is composed of long-chain fatty acids with an alcohol attached, often derived from vegetable oils like fatty acid methyl ester (FAME). It is produced through the Transesterification reaction of a vegetable oil with methyl alcohol or ethyl alcohol in the presence of potassium hydroxide (KOH) or sodium hydroxide (NaOH) catalyst, which produces biodiesel and glycerin. BHD has a good oxidization stability as same as conventional diesel fuel unlike BOD. BHD has the same components as those contained in conventional diesel fuel. BHD is characterized by its high cetane index, zero sulfur, and zero aromatic carbons, presenting a possibility that it can more effectively reduce the exhaust gas (PM, NO x ) than conventional petro diesel fuel when used in combination with appropriate motor vehicle technologies. Currently FAME contains high viscosity and double bond. Biohydrofining of vegetable oil appears to be a better option than Transesterification in producing diesel substitute because of high oxidation stability, low viscosity and disappearance of double bond in structure in BHD. However the cloud point of the hydrogenated oil is slightly worse than FAME warrants improvement considering the cold flow property requirement. The cold flow property of BHD can be improved by using hydroisomerization technologies with two kinds of noble metal catalysts (amorphous type and zeolite type).

This article illustrates a simple method for estimation of cetane indexes of vegetable oil methyl esters from their saponification and iodine numbers. The range of the calculated values covers all the cetane numbers of vegetable oil methyl esters determined experimentally. when it was applied to individual fatty acid methyl esters from C8 to C24, a straight line parallel to that of Klopfenstein was obtained.

The manifold pressure below which a diesel engine starts to misfire is related to the cetane number of the fuel. The method of engine throttling to misfire has been used to determine cetane quality of much smaller quantities of diesel fuel than can be used with the standard ASTM D 613 method. A comparison of reliability has been made between the two methods using identical test samples. The fact that published repeatability limits for ASTM D 613-84 are much smaller than the reproducibility limits suggests that there can be considerable bias at some laboratories using the standard method. A method of calibration and computation is presented that provides reliable estimates of the accuracy of misfire pressure results without reference to other laboratories. Confidence intervals determined for the misfire pressure method are consistent with the observed difference in the results determined on the one set of test materials by the two methods. This suggests that, in the procedure for engine throttling to misfire proposed here, the interlaboratory component of error could be small.

A method and apparatus consisting of a gas chromatographic reactor was developed to study the effect of antioxidants on lipid-containing systems. The oxygen uptake during the oxidation tests was continuously measured. The relative efficiencies, expressed as protective index, for butylated hydroxytoluene (BHT), propyl gallate (PG), α-tocopherol, citric acid, and ascorbic acid on the oxidation of linoleic acid at 85 C and 55 mmHg were determined. The effect of increasing the concentration of BHT (0.025, 0.05, and 0.1%) on the oxidation of safflower oil at 70 C and 45 mmHgO2 was observed. The method was found to be a rapid and reproducible approach to investigate the effect of antioxidants on polyunsaturated lipids.