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使用 Rancimat 方法测定氧化和热稳定性

使用 Rancimat 方法测定氧化和热稳定性

天然油脂、含油脂食品和化妆品、生物柴油和含氯聚合物（如PVC）等的加速老化测试（氧化稳定性指数和稳定时间）。

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使用 Rancimat 方法测定氧化和热稳定性

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天然油脂、含油脂食品和化妆品、生物柴油和含氯聚合物（如PVC）等的加速老化测试（氧化稳定性指数和稳定时间）。

我们提供三种测定稳定性的专用仪器：Rancimat用于评估含油脂食品、化妆品和天然油脂的诱导时间或氧化稳定性指数 (OSI)； 生物柴油 Rancimat用于测定生物柴油氧化稳定性； PVC Thermomat 通过脱氯化氢(DHC)方式用于聚氯乙烯 (PVC) 和其他含氯聚合物的热稳定性。

  • 用于天然油脂、生物柴油和 PVC 的专用氧化和热稳定性测试仪器。
  • 符合国际标准：AOCS Cd 12b-92、ISO 6886、EN 14112、EN 15751、EN 16568、ISO 182第3部分
  • 方便高效：单独分析单个样品或同时分析8个样品
  • 强大的软件：仪器控制、数据管理和评估结果

产品彩页：892专业型 Rancimat油脂氧化稳定性测定仪

               产品彩页：893专业型 Rancimat生物柴油氧化安定性测定仪 

               产品彩页：895专业型 PVC 热稳定性测定仪 

氧化稳定性测定工作原理

我们建立的 Rancimat 方法是通过提高样品温度并通入持续的空气流，使样品加速老化过程。 气流将挥发性氧化产物从样品容器传送到装有蒸馏水的容器中。 仪器测量水溶液的电导率，电导率突然增加的时间就表示诱导时间。

 

诱导时间是检测食品工业中油脂质量的标准参数。

聚合物的热稳定性测定工作原理

脱氯化氢试验是通过加热聚合物样品，使其分解之后进行测定。 分解之后会释放出气态氯化氢 (HCl)。连续的氮气流将释放的 HCl从样品容器传送到装有蒸馏水的测量杯中。 在样品容器中，连续测量电导率。一旦形成 HCl，电导率就会增加。与测量开始时相比，达到 50 µS/cm 的时间就是稳定时间，这是测定热稳定性的重要参数。

您的选择：单独测定或进行批量分析

瑞士万通Rancimat氧化稳定性测定仪有八个测量位，每个测量位有独立测量启动键。

 

但是，如果您需要分析大批量样品序列，您可以多可连接四台仪器，同时分析 32 个样品。

StabNet软件：仪器控制、数据评估、管理和存储结果

StabNet 是一款成熟的稳定性测定软件。 该软件负责仪器控制和数据处理，从结果计算到数据库管理和报告生成。

 

如果需要，该软件可以设置为客户端-服务器网络版，为您提供数据访问和管理以及用户权限管理方面等附加功能。

哪款氧化稳定性测试仪符合您的要求？

与瑞士万通当地销售联系，寻找满足您需求的理想解决方案！

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了解 Rancimat 测定仪如何评估天然油脂的氧化稳定性

查询氧化稳定性测定仪相关应用

Stability measurement – FAQs

Our established Rancimat method is based on accelerating the oxidation process of the sample by raising its temperature and passing a continuous stream of air through it. The air flow transports volatile oxidation products from the sample vessel into a vessel containing distilled water. The oxidative stability instrument measures the conductivity of the water. A sudden, strong increase in conductivity marks the induction time.

The induction time is a standard parameter in quality testing of oils and fats in the food industry and gives indications about the remaining shelf life of a product.

The dehydrochlorination test is done by heating the polymer sample to induce decomposition. As a result of the decomposition, gaseous hydrochloride (HCl) is released. The HCl that is released is transported from the sample vessel into a vessel containing distilled water by means of a continuous stream of nitrogen. In the sample vessel, the conductivity is continuously measured. Once HCl is formed, the conductivity increases. The time at which a 50 µS/cm increase is reached compared to the beginning of the measurement is the stability time, a measure of thermostability.

The Rancimat method is widely recognized by international standards for determining the oxidation stability of fats, oils, and biodiesel. It is included in several standards, including:

  • ISO 6886 Animal and vegetable fats and oils – Determination of oxidative stability (accelerated oxidation test)
  • AOCS Cd 12b-92 Oil stability index. Sampling and analysis of commercial fats and oils
  • EN 14112 Fat and oil derivatives – Fatty Acid Methyl Esters (FAME) – Determination of oxidation stability (accelerated oxidation test) (also referenced in DIN EN 14214)
  • ASTM D6751 Standard Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels

Yes, the OSI is a synonym for the induction period, which is the time at a specific temperature and gas flow until the oil turns rancid. This is exactly what the Rancimat determines.

There are different norms available to determine the oxidation stability index. Each norm has slightly different parameters. Find out more about the parameters of the norms in this application note:

Application Note: Oxidation stability comparison of AOCS Cd 12b-92 and EN ISO 6886

The Rancimat method is the most common method to determine the oxidation stability of edible oils. It provides reliable and rapid results suitable for both research and industrial quality control purposes.

Learn more in our blog:

Blog: How to determine if your edible oils are rancid

You can determine the oxidation resistance of biodiesel with the 893 Professional Biodiesel Rancimat.

During measurement, a stream of air is passed through the fatty acid methyl ester sample (Biodiesel) contained in a closed and heated reaction vessel. This treatment results in oxidation of the alkyl ester molecules in the sample, with peroxides initially being formed as the primary oxidation products. After some time, the fatty acid methyl esters begin to decompose, and the secondary oxidation products thus formed include low-molecular organic acids such as acetic acid and formic acid in addition to other volatile organic compounds. These are transported by the airstream to a second vessel containing distilled water, where the conductivity is measured continuously. The organic acids can be detected by the increase in conductivity. The time that elapses until these secondary reaction products appear is called induction time or induction period and characterizes the quality of the sample.

Application Note: Oxidation stability of diesel, biodiesel, and blends

Application Note: Oxidation stability of fatty acid methyl esters (FAME, biodiesel)

The shelf life of materials is influenced by various factors including:

  • temperature
  • oxygen exposure
  • UV light
  • microbial growth

The Rancimat method exclusively measures oxidation stability at elevated temperatures, making it unsuitable for direct shelf-life determination. However, the induction time provides an indication of oil stability when other influencing factors are excluded. Our software allows extrapolation to room temperature using the Arrhenius equation, offering a rough shelf-life estimate.

For accurate shelf-life determination, samples must be stored under defined conditions, and test results should then be correlated with the induction time.

The sample size varies depending on the norm and the sample type.

  • For edible oil samples, the sample size is typically 3 g
  • For solid food samples, e.g., grinded nuts, the sample size is 0.5 g.
  • For Biodiesel samples, the size varies between 3.5 g and 7.5 g.
  • For PVC samples, the sample size is typically 0.5 g.

Find more information about the recommended sample sizes in our application documents:

Applications for stability measurements

Emulsions cannot be measured directly with the Rancimat. However, we developed two methods to make it possible.

The first method is a cold extraction. For this, the fat of the emulsion is extracted with a non-polar solvent like low boiling petrol ether. The solvent which contains the oil is then separated from the matrix and evaporated in a rotavapor. The left-over oil is measured as a normal oil.

As the extraction process includes some labor-intensive steps, we developed an alternative method. In this second method, we measure the antioxidation capacity of the emulsion on a material that normally decomposes very quickly at elevated temperatures. We use PEG3000 as carrier material and we call the method PEG Method.

Find out more about the PEG method