Analyzing Vitamin C Concentrations in Plant Extracts: Experimental Insights, Theoretical Expectations, and Implications

Categories: Biology

Micronutrients known as vitamins play a crucial role in maintaining the body's health and well-being, and they are required in small quantities. One such vital vitamin is Vitamin C, also referred to as ascorbic acid. Its significance extends to cell division, cell wall synthesis, and the inhibition of harmful compounds like hydrogen peroxide.

In this experiment, the objective is to analyze various material samples to determine the ascorbic acid content in each. The chosen indicator for this analysis is the dichlorophenolindophenol (DCPIP) solution.

Through the reaction between the DCPIP solution and the sample extract solution, the experiment aims to quantify the amount of Vitamin C present in each sample.

To delve further into the experiment, it is crucial to understand the mechanism of the DCPIP reaction with ascorbic acid and how it leads to a measurable change in the solution's color. This color change serves as an indicator of the Vitamin C concentration, providing a reliable method for analysis.

Furthermore, exploring the sources of Vitamin C and its role in human nutrition can offer valuable insights.

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Citrus fruits, berries, and green leafy vegetables are rich sources of Vitamin C, and its deficiency can lead to scurvy, a condition historically observed in sailors lacking access to fresh fruits and vegetables during long sea voyages.

Understanding the broader context of the experiment, including the potential applications of the findings in addressing Vitamin C deficiencies or optimizing dietary recommendations, adds depth to the significance of the research. Moreover, considering the impact of environmental factors on Vitamin C levels in various materials can contribute to a more comprehensive interpretation of the experimental results.

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Units Method to control
Independent variable The type of food sample - For a sample of ascorbic acid solution, prepare it by taking a certain volume from its container and put it in a clean burette.
For sample of cabbage, grind 10 g of its flesh and mix it with distilled water, then filter the mixture to get 50 cm3 of a clear solution.
For sample of onion, grind 10 g of its flesh and mix it with distilled water, then filter the mixture to get 50 cm3 of a clear solution.
For sample of pineapple, grind 10 g of its flesh and mix it with distilled water, then filter the mixture to get 50 cm3 of a clear solution.

Dependent variable

The concentration of Vitamin C in the food sample

mg cm-3

Calculate and record the concentration of Vitamin C in the food sample by using the formula:


where n is the average volume of the food sample solution needed to decolourise DCPIP solution.

Constant variables

The type of indicator used


Use the same type of indicator to detect the presence of Vitamin C in the food samples, which is DCPIP solution.

The volume of DCPIP solution used


Fix the same volume of the DCPIP solution used, which is 1 cm3.

The concentration of DCPIP solution


Fix the same concentration of DCPIP solution for all sets, which is 1%.

The mass of food sample taken


Use the same mass of 10 g for all food samples by using a balance.

The initial volume of extract taken


Ensure that all volumes of extract are fixed to 50 cm3 by using filter funnel.


Material Volume Concentration Mass
DCPIP solution 100 cm3 1% -
Vitamin C solution (Ascorbic acid) 10 cm3 1% -
Distilled water - - -
Pineapple - - 10 g
Cabbage - - 10 g
Yellow onion - - 10 g


Apparatus Quantity Uncertainty
50 cm3 burette with stand 1 ± 0.5 cm3
50 cm3 conical flask 5 -
400 cm3 beaker 1 -
100 cm3 beaker 5 -
Tissue paper 1 roll -
10 cm3 measuring cylinder 1 ± 0.1 cm3
Analytical balance 1 ± 0.01 g
Mortar and pestle 1 -
Glass rod 1 -
Filter funnel 1 -
Filter paper 3 -
Knife 1 -
Dropper 1 -
Chopping board 1 -
Forceps 1 -


  1. Begin by finely grinding 10 g of selected fruits, ensuring a thorough breakdown of cellular structures, and subsequently mix the resulting fruit powder with 50 cm3 of distilled water.
  2. Filter the plant macerate meticulously to obtain a clear 50 cm3 solution, which will serve as the plant extract for the titration process.
  3. Ensure the burette is meticulously cleaned, rinsed, and filled with a precisely prepared 1% Vitamin C solution, noting the initial burette reading for accurate titration.
  4. In a conical flask, transfer precisely 1 cm3 of a 1% DCPIP solution, positioning the flask beneath the prepared burette for titration.
  5. Methodically introduce the Vitamin C solution drop by drop into the DCPIP solution, gently shaking the conical flask after each addition until the DCPIP solution transitions to a distinct colorless state.
  6. Record the volume of the Vitamin C solution used at the point of color change, ensuring precision in measurement.
  7. Repeat the titration process (Steps 4 to 6) and calculate the average volume of the Vitamin C solution consumed during the reaction.
  8. Repeat the entire titration procedure (Steps 4 to 7) using the plant extract solution, allowing for a comparative analysis of Vitamin C content.
  9. Utilize the obtained data to calculate the concentration of Vitamin C in each plant extract solution, offering insights into the variations in Vitamin C content among different fruit samples.

Additionally, understanding the significance of Vitamin C in the context of its antioxidant properties and its role in supporting the immune system can provide a broader perspective on the implications of the experiment. This knowledge may contribute to the interpretation of results and potential applications in promoting health and nutrition.

Qualitative Data

  1. Upon the introduction of cabbage extract to the DCPIP solution, a noticeable transformation occurs as the solution transitions from a deep, dark blue hue to a completely colorless state.
  2. In the case of the onion extract, the interaction with the DCPIP solution results in a distinctive alteration of color, shifting from the initial dark blue to a subtle and captivating light purple tint.
  3. The introduction of pineapple extract to the DCPIP solution induces a captivating change in color, as the once dark blue solution transforms into a delicate and intriguing light red shade.

To augment the qualitative findings, it is beneficial to explore the potential factors contributing to the observed color variations. Consideration of the specific compounds present in each plant extract, such as antioxidants and pigments, could provide insights into the unique reactions with the DCPIP solution. Furthermore, delving into the nutritional significance of these plant extracts and their varying Vitamin C concentrations can add depth to the qualitative observations, connecting the experimental outcomes to broader implications for dietary choices and health.

Quantitative data
The Volume of Extract Solution Used in Six Trials for Different Food Samples

Sample name Volume of extract solution used / cm3
Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Trial 6
Ascorbic acid 1.00 0.70 1.00 0.60 0.10 0.20
Cabbage 4.50 4.50 3.50 6.90 6.80 6.50
Onion 2.00 3.10 2.40 5.10 3.70 4.30
Pineapple 11.00 14.00 11.90 10.90 14.00 11.50

The Average Volume of Extract Solution, Concentrations of Vitamin C in Different Food Samples and their Standard Deviations

Sample name Average volume / cm3 Standard deviation Concentration of Vitamin C / mg cm-3 Standard error
Ascorbic acid 0.60 0.3847 0.008333 0.0053432
Cabbage 5.45 1.4584 0.000917 0.0002455
Onion 3.43 1.1690 0.001456 0.0004959
Pineapple 12.22 1.4275 0.000409 0.0000478


  1. The graphical representation in the form of a bar chart does not reveal any discernible trends, as each sample's Vitamin C concentration stands independently.
  2. The decision to use a bar chart stems from the discrete nature of the independent variable, representing different types of samples with distinct data points.
  3. Given the discrete nature of the data, scatter plots are deemed unsuitable for this experiment, as they typically depict relationships between continuous variables.
  4. Excluding ascorbic acid, the highest observed concentration of Vitamin C in the bar chart is 0.001456 mg cm-3, originating from the onion extract.
  5. In contrast, the lowest concentration is attributed to the pineapple extract, measuring 0.000409 mg cm-3.
  6. No constants are present in the bar chart, highlighting the dynamic nature of Vitamin C concentrations among the different samples.
  7. Experimentally, the ascending order of Vitamin C concentrations is Pineapple < Cabbage < Onion.
  8. However, this order contradicts the theoretical expectation, which posits Onion < Cabbage < Pineapple.
  9. The theoretical discrepancy raises questions about the factors influencing Vitamin C concentrations in the selected plant extracts.
  10. Considering Vitamin C's acidic nature, the expectation is that foods with higher Vitamin C content should exhibit a more pronounced sour taste.
  11. This aligns with the hypothesis that low Vitamin C content results in a less sour taste due to lower acidity, while high Vitamin C content leads to increased sourness due to elevated acidity.
  12. The DCPIP solution's ability to decolourize in the presence of Vitamin C further supports the relationship between concentration and decolourization efficiency.
  13. Higher concentrations of Vitamin C in food samples lead to faster decolourization of the DCPIP solution, with the pineapple extract expected to achieve this with the least volume.
  14. Despite having the most concentrated Vitamin C, the pineapple extract does not decolourize the DCPIP solution but induces a color change from dark blue to red.
  15. In contrast, the cabbage extract should decolourize the DCPIP solution with a volume greater than pineapple but less than the onion extract due to its intermediate Vitamin C concentration.
  16. The experimental values, however, deviate from the theoretical expectations, with onion extract exhibiting the highest Vitamin C concentration and pineapple the lowest.
  17. A potential source of discrepancy lies in incomplete titration, where reactions may not have been allowed to proceed until the DCPIP solution completely changed color.
  18. The inclusion of a control experiment using 1% ascorbic acid allows for standardization and comparison, acting as a reference point for the reliability of other values.
  19. Notably, the error bars associated with cabbage, onion, and pineapple extracts are relatively small, indicating a limited range and less deviation in the data.
  20. Conversely, the longer error bar for 1% ascorbic acid suggests a wider range, potentially rendering its concentration data less reliable.
  21. The discussion underscores the importance of considering experimental variables, titration completeness, and control experiments in interpreting and validating results in studies involving Vitamin C concentrations in plant extracts.
Updated: Feb 20, 2024
Cite this page

Analyzing Vitamin C Concentrations in Plant Extracts: Experimental Insights, Theoretical Expectations, and Implications. (2024, Feb 08). Retrieved from

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