Vitamin C Titration Lab

Research Questions:

  1. How do we work within the limitations of this measurement tool in order to produce an accurate and precise experimental measurement?

  2. What is the ascorbic acid content in a Vitamin C tablet?

Learning Objectives:

  1. Use surface tension based micro paper analytical devices to make accurate measurements of ascorbic acid concentrations in Vitamin C tablets

  2. Use a color reading app to correctly detect experimental endpoint

  3. Use acid-base concepts to predict and test endpoint

  4. Use stoichiometry concepts to measure the ascorbic acid content of a Vitamin C tablet

  5. Use scientific data to develop experimental procedures

  6. Determine sources of experimental failure and iterate on experimental procedure

  7. Evaluate the significance of experimental data using appropriate statistics

To Do List:

Step 1: Read lab background, watch videos, and visit links provided about experimental context on this page

Step 2: Read lab procedure

Step 3: Watch corresponding lab tutorial

Step 4: Answer pre-lab questions

Step 5: Perform lab experiment

Step 6: Answer post-lab questions

Did you know that 45% of College students are food insecure and may have to make choices between paying rent, buying books or eating?

Food Insecurity:

Everyone has heard of the college student who runs on caffeine and ramen noodles. College students are notorious for poor food choices and staying up late. This problem actually is worse than most people realize. Food insecurity is when people do not have access to adequate food either because of economic or social reasons.1 “A survey released this week by Temple University’s Hope Center for College, Community and Justice indicated that 45 percent of student respondents from over 100 institutions said they had been food insecure in the past 30 days.”2 When students do not have access to healthy food, a common deficiency is a vitamin C deficiency.

Traditional ways of attending college have been left in the past. Today, 71% of students attending college are considered non-traditional. This means that they are either working full-time, a part time student, are financially independent, caring for another dependent, or didn’t receive a traditional high school education.3 This evolving way that people are attaining a college education means that they are incurring high charges while trying to get good grades. This often leads to choices having to be made like purchasing textbooks or having healthy food. Not having access to healthy, nutritional food affects the student’s ability to study and achieve the same grades as their peers. Lack of Vitamin C, which is often found in students that are food insecure, can lead to fatigue and depression.4 This is something that is often experienced by collegiate students, so lacking Vitamin C just compiles and worsens that issue. Studies have shown that students who identify as food insecure generally receive lower grades than students who are well nourished.5

Figure 1. Grades received based on food insecurity5

Visit this link to find out what Feeding America is doing to combat college food insecurity: Addressing Food Insecurity Among College Students.

College Hunger Landscape - Brief.pdf

Students who experience food insecurity are not equally represented across all demographics. A study done by the 2016 Hunger on Campus study showed that 40% of non-hispanic white students reported food insecurity while a much higher 57% of African American students identified as food insecure. It was also found that 56% of first-generation students experienced food insecurity as compared to 45% of students who had at least one parent with a college degree.1 Experiencing food insecurity is something that was normalized for a college lifestyle but it is more understood that these food deficiencies are causing problems medically and in the classroom.

Check out Livia Schiavinato Eberlin who is doing some great microfluidics work with cancer detection!

Nutrition and Vitamin D Deficiency:

L-ascorbic acid, known commonly as Vitamin C, plays an important role in the construction of collagen in human connective tissues, fibrous tissue, teeth, bones, skin, and capillaries.6,7 It is required for the synthesis of some neurotransmitters and aids the circulatory system in the uptake of iron.7 The compound is found most commonly in citrus fruits, causing the characteristic sharp tangy-ness associated with that fruit family.6 Other sources of Vitamin C include red and green peppers, tomatoes, broccoli, and greens.8

Vitamin C is considered an essential vitamin, due to the human body's inability to produce it naturally or store it in the body. It has to be obtained either through diet or supplements.9 Ascorbic acid is an antioxidant, so it helps prevent or delay cell damage caused by oxidative stress or free radicals. The advantages of a healthy Vitamin C intake are protection against cardiovascular disease, the maintenance of proper immune function and iron absorption, and the regeneration of other antioxidants in the human body.8

This image shows the chemical structure of ascorbic acid: HC6H7O6, (2R)-2-[(1S)-1,2-dihydroxyethyl]-3,4-dihydroxy-2H-furan-5-one.

Prolonged Vitamin C deficiency leads to the development of scurvy, a condition which progressively worsens over time. At 8-12 weeks the symptoms begin with loss of appetite and weight, fatigue, and irritability. They progress to more serious symptoms of swelling and subcutaneous bleeding, pain in muscle groups and bones, poor wound healing, and gum disease - among others. Eventually, the symptoms can include spontaneous bleeding, fever, convulsions, etc. and can be fatal if left untreated.11

Generally, scurvy is associated with seafaring voyages, like long trade routes, whaling expeditions, explorations, and migrations across oceans. This is due to the difficulty of obtaining and storing fresh produce during long stints on the open ocean. However, any demographic with a lack of Vitamin C consumption can be at risk of developing scurvy, including college students.

Analysis of Vitamin C:

Because of vitamin C’s importance in health, it is helpful to be able to determine the vitamin C content in supplements and food. It is also interesting to be able to determine how the vitamin C content is affected by cooking. In this experiment, we will do a titration analysis of Vitamin C by reacting it with iodine. The reaction involves the oxidation of ascorbic acid to dehydroascorbic acid with the reduction of iodine to iodide.

C6H8O6 (aq) + I2 (aq) --> C6H6O6 (aq) + 2 I- (aq) + 2 H+ (aq)

Starch is used in this lab as the indicator. When excess iodine is present (after the equivalence point), the iodine and starch combine to form a complex with a very dark color.

References:

  1. Food Insecurity on College Campuses. https://www.clasp.org/press-room/news-clips/food-insecurity-college-campuses (accessed Jul 28, 2020).

  2. Laterman, K. Tuition or Dinner? Nearly Half of College Students Surveyed in a New Report Are Going Hungry. https://www.nytimes.com/2019/05/02/nyregion/hunger-college-food-insecurity.html (accessed Jul 28, 2020).

  3. College Student Hunger Statistics and Research. https://www.feedingamerica.org/research/college-hunger-research (accessed Jul 28, 2020).

  4. Johnson, L. E.; By; Last full review/revision Aug 2019| Content last modified Aug 2019. Vitamin C Deficiency - Nutritional Disorders. https://www.merckmanuals.com/professional/nutritional-disorders/vitamin-deficiency-dependency-and-toxicity/vitamin-c-deficiency (accessed Jul 28, 2020).

  5. Dedman, B. Majority of College Students Experience Food Insecurity, Housing Insecurity, or Homelessness. https://www.aacu.org/aacu-news/newsletter/majority-college-students-experience-food-insecurity-housing-insecurity-or (accessed Jul 28, 2020).

  6. National Center for Biotechnology Information Ascorbic acid (Compound). https://pubchem.ncbi.nlm.nih.gov/compound/54670067#section=Pharmacology-and-Biochemistry (accessed July 27, 2020).

  7. U.S. Department of Health & Human Services Vitamin C. https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/ (accessed July 27, 2020).

  8. U.S. National Library of Medicine Vitamin C. https://medlineplus.gov/vitaminc.html (accessed July 27, 2020).

  9. Raman, R. 7 Impressive Ways Vitamin C Benefits Your Body. https://www.healthline.com/nutrition/vitamin-c-benefits (accessed July 27, 2020).

  10. Millipore Sigma L-Ascorbic acid. https://www.sigmaaldrich.com/catalog/product/sial/a92902?lang=en&region=US&gclid=CjwKCAjw9vn4BRBaEiwAh0muDP_pPnU406ikFpGm0YilY9dRs70mdkwY40-DM8K3JsBI8u0ivSjmeRoCqVEQAvD_BwE (accessed July 27, 2020).

Crosta, P. Everything you need to know about scurvy. https://www.medicalnewstoday.com/articles/155758 (accessed July 27, 2020).