Peroxide Value in Oil: Titrator vs. Photometer – Choosing the Right Method for Accurate Measurement

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The peroxide number is a crucial parameter used in the analysis of oils, particularly in the food, pharmaceutical and cosmetic industries

1. Introduction to measuring peroxide number in oil

The peroxide number is a crucial parameter used in the analysis of oils, particularly in the food, pharmaceutical, and cosmetic industries. It provides valuable information about the oxidative stability and quality of oils.

Traditionally, the peroxide number has been measured using manual titration methods, which can be time-consuming and prone to human error. However, advancements in technology have introduced alternative methods such as photometric analysis and automatic titration. By understanding the differences and considerations associated with each method, professionals in the field can make informed decisions when selecting the most appropriate technique for their specific needs.

Understanding the importance of peroxide number analysis

When it comes to oil, freshness is key. Nobody wants to cook their french fries in rancid oil, right? That’s where peroxide number analysis comes in. The peroxide number is a measure of the amount of peroxides present in oil, which can indicate its level of oxidation. By determining the peroxide number, we can assess the quality and shelf life of the oil, ensuring that it meets the standards for consumption or industrial use.

Common applications of peroxide number measurement in the oil industry

Peroxide number analysis is widely used in the oil industry for various purposes. It can be applied to monitor the quality of edible oils, such as vegetable or olive oil, to ensure they are safe for consumption. In addition, peroxide number measurement is crucial in the production of cosmetic oils and pharmaceuticals, as oxidized oil can have a negative impact on the final product’s stability and effectiveness. By measuring the peroxide number, producers can detect any potential issues and take corrective actions to maintain product quality.

Oils with a peroxide value ranging from 1 to 3 mmol O2 / kg are considered fresh and of good quality.

Oils whose peroxide value ​​does not exceed 10 mmol O2 / kg are considered suitable for human consumption.

The peroxide number is considered an indicator of the initial phase of oil oxidation because the resulting hydroperoxides are extremely unstable and decompose very quickly in the so-called secondary oxidation products.

2. Overview of photometric method for peroxide number determination

Principles of photometric analysis

The method involves measuring the absorption of light by peroxides in the oil sample. The more peroxides present, the higher the absorption, which can be quantified using a photometer.

Procedure for measuring peroxide number using a photometer

To determine the peroxide number using a photometer, you’ll need to mix the oil sample with a solvent and a reagent that reacts with the peroxides. After allowing the reaction to occur, you can place the sample in the photometer, which will measure the absorbance and convert it into a peroxide number value.


Portable Photometer for Determination of Peroxide Value in Oils

The HI83730 Portable Photometer for the Determination of Peroxide Value in Oils combines accuracy and ease of use in an ergonomic, portable design.

A user can accurately determine the peroxide value of olive oil within a 0.0 to 25.0 meq O2/kg range using the HI83730-20 ready made reagents.

  • Built-in Timer
  • Automatic Shut Off
  • Ready-made Reagents

Advantages and disadvantages of photometric method

The photometric method offers some advantages. It’s a quick and straightforward technique that provides results in a matter of minutes. Plus, it requires minimal sample preparation, making it convenient for routine analysis. However, it’s worth noting that photometric analysis may not be as precise as other methods and can be influenced by interferences from other substances in the oil sample.

3. Introduction to automatic titration for peroxide number analysis

Understanding the principle of automatic titration

Automatic titration takes the peroxide number analysis to a whole new level. It involves using a titrator, like the ones from Hanna Instruments, which automatically dispenses a solution that reacts with the peroxides in the oil. By monitoring the change in pH, the titrator can determine the peroxide number.

Procedure for conducting automatic titration for peroxide number measurement

To conduct automatic titration for peroxide number analysis, you’ll need to set up the titrator with the appropriate reagents and program it with the desired parameters. The titrator will then dispense the titrating solution into the oil sample until the reaction is complete. The peroxide number is calculated based on the volume of solution used.


Automatic Potentiometric Titrator

The HI931 Automatic Titrator is the answer to your dedicated titration needs. Fully customizable, the HI931 delivers accurate results and intuitive user experience, all in a compact package. Titrate for a variety of measurements at the push of a button including acids, bases, redox, and selective ions. No additional programming upgrades to purchase. The only things you need to start using the HI931 are a sensor and titrant.

  • Small footprint so you can fully optimize your benchtop
  • Unmatched 40,000-step dosing pump for small volumes of titrant to help you achieve a very precise endpoint for greater consistency
  • Flexibility to store up to 100 methods

Benefits and limitations of automatic titration method

Automatic titration offers several advantages over other methods. It provides accurate and precise results, making it suitable for quality control purposes. Additionally, it eliminates human error and reduces the need for manual calculations. However, automatic titration may require more complex equipment and setup compared to photometric analysis, which could be a limitation depending on the resources available.

4. Comparison of photometer and automatic titration methods

Accuracy and precision comparison between photometer and automatic titration

When it comes to accuracy and precision, automatic titration takes the crown. The titration method provides more reliable results due to its ability to eliminate interferences and its high level of control. However, photometric analysis can still be useful for quick screening purposes, as long as the potential limitations are considered.

Time and cost considerations for each method

In terms of time and cost, photometric analysis takes the lead. It’s a speedy technique that requires minimal consumables, making it cost-effective for routine analysis. On the other hand, automatic titration may require more time and investment due to the need for specialized equipment and reagents.

Equipment requirements and ease of use for both methods

Photometric analysis wins the contest in terms of equipment requirements and ease of use. A basic photometer is all you need and the procedure is relatively straightforward. In contrast, automatic titration may require a more advanced titrator and additional accessories, which could be a barrier for some laboratories. Nonetheless, the accuracy and efficiency of automatic titration make it worth considering if resources permit. 

In conclusion, both the photometric method and automatic titration have their merits in measuring the peroxide number in oil. The choice between the two methods will depend on the specific needs of the analysis, as well as the available resources and desired level of accuracy.
So, whether you opt for the photometer or the titrator, rest assured that you’ll get the job done and keep your oils fresh and fabulous!

5. Factors influencing accuracy and precision of peroxide number measurement

Impact of sample preparation on measurement results

When it comes to measuring the peroxide number in oil, sample preparation plays a crucial role in obtaining accurate and precise results. The freshness of the oil sample is important, as peroxide levels can change over time. It is advisable to test the oil as soon as possible after extraction or acquisition. 

Another factor to consider is the sample size. Both photometers and automatic titration methods require a specific volume of oil for analysis. It is crucial to carefully follow the instructions for sample size, as using too much or too little oil can affect the accuracy of the results.

Potential interferences and how they can affect accuracy

Several factors can interfere with the accurate measurement of peroxide number in oil. External substances such as metals, antioxidants, and impurities can impact the results. It is important to ensure that the oil sample is free from any contaminants that could affect the peroxide number measurement. 

Additionally, the presence of other chemical compounds in the oil can interfere with the reaction between peroxides and the reagent used for analysis. It is essential to consider these potential interferences and choose a method that minimizes their impact to obtain reliable results.

6. Advantages and limitations of using a photometer for peroxide number analysis

Considerations for specific types of oils

While photometers can be used for peroxide number analysis across different types of oils, it is important to consider the specific characteristics of the oil being tested. Some types of oils may have different reaction rates or potential interferences, which could affect the accuracy of the measurements. It is advisable to consult the instrument’s manual or seek guidance from experts when analyzing oils with unique properties.

Potential challenges and limitations of photometric analysis

Photometric analysis for peroxide number measurement also has its limitations. Photometers rely on colorimetric reactions, which may be affected by external factors such as ambient light. Additionally, the accuracy of photometers is often limited by the precision of the reagents used. It is essential to handle the reagents carefully and ensure their integrity to maintain accurate results.

7. Advantages and limitations of using automatic titration for peroxide number measurement

Benefits and strengths of using automatic titration method

Automatic titration offers several advantages for peroxide number measurement. It provides highly accurate and precise results, making it suitable for applications where precise measurements are crucial. The method allows for customizable titration parameters, enabling flexibility to adapt to different oil types and sample sizes. Automatic titration also eliminates the subjective interpretation of endpoint detection, ensuring consistency in measurements.

Factors to consider when applying automatic titration to different oil types

When using automatic titration for peroxide number analysis, it is important to consider the specific characteristics of the oil being tested. Viscosity, acidity, and potential interferences can influence the titration reaction and affect the accuracy of the results. Understanding these factors and adjusting the titration parameters accordingly can help ensure reliable measurements across different oil types.

Possible drawbacks and limitations of automatic titration

While automatic titration provides precise results, it does require an initial investment in the instrument and regular maintenance to function optimally. The method also requires well-trained operators to set up the instrument correctly and interpret the results accurately. Additionally, the analysis time for automatic titration can be longer compared to photometers. These limitations should be considered when choosing the appropriate method for peroxide number measurement.

8. Conclusion and recommendations for choosing the appropriate method

Summary of key findings and insights from the comparison

In summary, both photometers and automatic titration methods have their advantages and limitations for peroxide number measurement in oil. Photometers offer portability, quick measurements, and user-friendly interfaces. Automatic titration provides high accuracy, customizable parameters, and consistency in measurements.

Factors to consider when selecting between photometric analysis and automatic titration

When choosing between the two methods, it is essential to consider factors such as the specific requirements of the application, the characteristics of the oil being tested, and the available resources and expertise. If portability and quick measurements are a priority, a photometer may be the preferred choice. On the other hand, if highly accurate and customizable measurements are crucial, automatic titration may be more suitable. 

Ultimately, choosing the appropriate method depends on the specific needs and constraints of the analysis. Consulting with experts or conducting a thorough evaluation of the instruments and their capabilities can help make an informed decision.

9. Conclusion and recommendations for choosing the appropriate method

In conclusion, both the photometer and automatic titration methods offer valuable means of measuring peroxide number in oil.

The photometer provides quick and accurate results, making it suitable for routine analysis.
On the other hand, automatic titration offers improved precision and is well-suited for laboratories handling a high volume of samples.

When selecting the appropriate method, factors such as sample type, time constraints, equipment availability, and desired level of accuracy must be considered.

Ultimately, it is recommended to assess individual needs and resources to make an informed decision that aligns with the specific requirements of the oil analysis.

By choosing the most suitable method, professionals can ensure reliable and efficient peroxide number measurement, contributing to the overall quality control of oils in various industries.

Have questions?

Contact a Hanna Technical Specialist at or using our contact form.


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