Comparison of different methods for the determination of the oil content in oilseeds

The investigation and assessment of the oil content of oilseeds are important criteria, especially for the oil milling trade. Standard methods for the determination of the oil content of oilseeds are very time consuming, with extraction periods of 4 to 8 h. Three different oilseeds—rapeseed, sunflower, and soybean—are extracted by supercritical fluid extraction (SFE), accelerated solvent extraction, microwave-assisted extraction, solid fluid vortex extraction, and Soxtherm, and the results are compared with the result of the German Fat Science Society (DGF) standard method B-I 5 (87). Besides, the extracts are analyzed regarding the content of tocopherols as a parameter for mild extraction conditions and the content of diglycerides and free fatty acids as parameters for the content of more polar lipids. The results of the determination of the oil content under optimal conditions are comparable with the results of the DGF standard method B-I 5 (87). There are no significant differences between the different methods. The content of tocopherols is dependent upon the extraction method and the type of oilseed. The highest content is obtained by SFE. The content of diglycerides and free fatty acids varied according to the oilseed.     

Simultaneous determination of moisture and oil content in oilseeds by pulsed nuclear magnetic resonance

Pulsed nuclear magnetic resonance technique using Carr-Purcell-Meiboom-Gill (CPMG) sequence has been used for simultaneous determination of moisture and oil content in rapeseed-mustard. This method involves sampling the free induction decay (FID) following 90° pulse in the CPMG sequence and resolving the trace of the amplitude of the CPMG echo signals into exponentially decaying liquid components of oilseeds. The data show that water in oilseeds generally exists in 2 phases and the relatively slow decaying component disappears around moisture content of 7% and below. The moisture and oil content have been determined by the method for 34 samples of 5 different varieties of seeds at varying moisture levels (∼3% to 22%). The measured moisture and oil content have been compared with the values obtained by the oven drying method and earlier known FID method of pulsed nuclear magnetic resonance (NMR) respectively, and the agreement is fairly good for rapid estimation with standard deviation of 0.70% for oil content and 0.99% for moisture content. This is a rapid and nondestructive method for determination of both moisture and oil content without weighing and drying the seeds and also seems suitable for other matrix samples.     

Determination of oil content in oilseeds by analytical supercritical fluid extraction

The total oil content of soyflakes, canola seed and wetmilled corn germ were determined by analytical supercritical fluid extraction (SFE) with carbon dioxide as the extraction solvent. Results obtained by SFE were in excellent agreement with those obtained by a conventional Soxhlet technique with organic solvents. The analytical-scale SFE technique yielded average means within one standard deviation of the means derived from the organic solvent-based methodology. Matrices containing both high and low oil content were successfully extracted with carbon dioxide at comparable precision to that obtained with the standard procedure. The supercritical fluid-based technique appears to be a suitable replacement for traditional extraction methods with organic solvents, thereby potentially eliminating the costs associated with solvent disposal and exposure of laboratory personnel to toxic and flammable solvents. Presented at the 4th International Symposium on Supercritical Fluid Chromatography and Extraction, Cincinnati, Ohio, May 20–22, 1992.     

Further studies on miscible oil

In continuation of a previous paper some properties of the same type of miscible oil are studied. The subjects considered are: determination of the constant K (which is characteristic of the emulsifier); mixture of two miscible oils; exposure of the miscible oil to the atmosphere; liquids with which miscible oil could not be obtained and, finally, miscible oil containing an insecticide for use in agriculture.     

动态库仑法快速测定重油中硫含量

采用动态库仑分析法对重油中硫进行测定。介绍测硫基本原理,仪器及试剂,实验方法。结果表明:该方法与标准方法〔GB/T38790《深色石油产品硫含量测定法(管式炉法)》〕测定值的绝对差值<0.15%。该方法的相对标准偏差(RSD)<3%,具有准确、快速、简便的特点。     

A spectrophotometric method for determination of solid fat content of palm oil

A new spectrophotometric method has been developed for determining solid fat content (SFC) of crude palm oil based on the different solubilities of the inherent carotenes in the solid and liquid components of the oil. The sample to be analyzed is tempered according to usual procedures and then either filtered or centrifuged to liberate the liquid component (olein). The carotene contents of the palm oil and olein as determined by spectrophotometry are then fitted into an equation to obtain the SFC. The carotenes are apparently insoluble in the solid component of palm oil. The standard deviation of analysis on palm oil samples at 25 C is 0.5% which is almost comparable to that of the wide-line NMR technique. The correlation coefficient of SFC measured by these 2 methods over a range of temperatures is 0.99. The new method can also be used to determine SFC of hybrid palm oil (Elaeis guineensis ×E. oleifera) and different palm oil-stearin blends.     

充油乳聚丁苯橡胶中油含量测定方法的改进

采用混合溶剂抽提法,对充油乳聚丁苯橡胶(ESBR)中的油含量进行测定,以对现行行业标准SH/T 1718-2002进行方法改进,进行了试样量、干燥时间的对比试验,并对改进后方法的精密度进行了考察.结果表明,改进后充油ESBR油含量的测定方法规定试样量为2 g,共抽提2次,每次抽提60 min,抽提后试样的干燥时间为1....     

Nuclear magnetic resonance spectrometry as a quick method of determination of oil content in rapeseed

A comparison of results obtained by the traditional extraction method for determination of oil content in rapeseed and those achieved by a commercial nuclear magnetic resonance (NMR) spectrometer revealed a very high correlation (r=0.987) between the results. The advantage of the NMR method, in relation to the extraction method, is the shorter time needed for a test: the result will be available in the course of a few minutes. Moreover, no inflammable chemicals are needed for the test, and the apparatus does not take up much room. On the other hand the NMR spectrometer must be placed in a room with a constant temperature, the seed samples must have the same temperature as the adjustment samples, and the oil content must be determined on dry matter basis.     

Simultaneous determination of oil and water contents in different oilseeds by pulsed nuclear magnetic resonance

Routine analysis of oil and water contents in different oilseeds with the Bruker Minispec pulsed nuclear magnetic resonance (NMR) analyzer (Bruker Analytische Mestechnik, Rheinstetten, Germany) is rapid (16 s measurements), precise, accurate and nondestructive. In 1991, subcommittee SC2 (oil seeds) of the Technical Committee Number 34 [organized by the International Standards Organization (ISO), Geneva, Switzerland] organized an international collaborative study for pulsed NMR analysis of oil content in whole rapessed. An additional study was performed in 1993 to extend the method to sunflower, linseed and soy seeds. The Draft International Standard ISO DIS/10565 (Draft International Standards, International Standards Organization, Geneva, 1993) describes the procedure of the pulsed NMR method for determination of oil content in rapeseed and presents the interlaboratory comparison results based on the calculations described in the Normative ISO 5725 (Draft International Standards, International Standards Organization, Geneva, 1993). The standard was approved in 1992 and will be published in 1993. The interlaboratory collaborative studies showed that the analyses of oil and moisture by pulsed NMR were either comparable or more repeatable than measurements done by the traditional methods. No statistical differences between determinations by the traditional and pulsed NMR methods were found. Simultaneous determination of percent moisture and percent oil content in whole seeds is possible with pulsed NMR by the spin-echo method. In addition, multiple components of the oil can be detected and quantitated by T2 analysis from the Carr-Purcell-Meiboom-Gill pulse sequence. The instrument is easy to calibrate with whole oilseeds, and the calibration can be checked periodically with the same seeds because the measurement is nondestructive. Pulsed NMR provides a rapid alternative to the long, laborious, traditional methods of analysis and offers substantial long-term savings of both time and money. Minimal operator training is required once the technique has been established for routine use. Presented at the 84th AOCS Annual Meeting & Expo, April 27, 1993, Anaheim, California.     

一种快速测定湿法磷酸固含量的方法

介绍计算法测定湿法磷酸固含量的原理,通过测定磷酸中固相物的真密度、磷酸样品的密度和清磷酸的密度,计算可得出固含量。该测定方法快速、简便,测定结果与国家标准法测定的结果比较无显著性差异,准确度能达到生产控制需要,可用于磷肥生产中磷酸固含量测定。     

工业级三偏磷酸钠含量测定方法的研究

三偏磷酸钠在酸性或碱性环境中易水解成正磷酸钠,通过加入BaCl2溶液沉淀除去样品中的磷酸二氢钠、焦磷酸钠,依据磷钼酸喹啉重量法测定水解后P2O5含量,得出三偏磷酸钠含量。本实验较系统地研究酸性或碱性环境下水解时间、加入BaCl2溶液浓度及加入BaCl2时样品溶液pH值对P2O5含量测定结果的影响。     

Heat pretreatment of oilseeds: effect on oil quality

We studied the effect of seed conditioning via a rapid preheating technique to destroy the activity of oil-degrading enzymes. Rape and sunflower seeds were heated via steaming, oven cooking, infrared, and microwave. After the pretreatment the oil was expelled from the seeds by a screw press and its quality was determined via the analysis of oxidative stability, peroxide value, free fatty acid content, phosphorus, and iron. From the results it was concluded that preheating of the seeds leads to the expected decreased activity of lipase, but nevertheless increased levels of phosphorus and free fatty acids were observed. However, increased levels of phenolic antioxidants markedly improved the oxidative stability of rapeseed oil. From the techniques studied for heating of the seeds, microwave and steaming appeared to be the most suitable techniques. Both methods gave markedly improved oxidative stability, whereas steaming seemed to result in less formation of free fatty acids than microwave heating. Infrared heating led to rapidly burnt seeds and off-flavours.     

氯化物含量较高废水中COD含量测定方法的改进

介绍了一种水质化学需氧量的测定方法——改进的重铬酸钾法.改进的方法节省了分析检验时间,方便了操作,满足了氯碱生产过程中氯离子质量浓度大于1 g/L样品的分析检验.     

腈纶含油率检验方法对比

使用索氏萃取法、红外光谱分析法、紫外分光光度法对腈纶短纤维含油率进行了测定,对其结果进行了假设检验分析,并比较了3种方法。结果表明:3种方法测定3．20 dtex×102 mm,6．00 dtex×102 mm, 2．78 dtex×64 mm腈纶短纤维的含油率分别为0．358％-0．365％,0．534％～0．550％,0．401％～0．410％; 假设检验分析表明,3种方法均接受假设,其检验水平一致;3种方法各有特点,在进行含油率测试时,可根据条件和需要,合理选择分析方法。     

喜树碱含量的测定方法研究

本文介绍了喜树碱含量的分析测定方法。样品采用了乙醇超声提取法从喜树叶中提取喜树碱,并用薄层层析法和高效液相色谱法分析测定喜树碱的含量。薄层层析法测定喜树碱的含量使用硅胶G做固定相,v（氯仿）：v（丙酮）=70∶30、v（甲醇）∶v（氯仿）=10∶90做展开剂。高效液相色谱法用v（甲醇）∶v（水）=55∶45做流动相,并且流动相流速为1.0 mL/min。在波长为254 nm,温度为25℃下检测。每次进样量为5μL。