Lab #1- Quantifying Vitamin C

1. Lab #1- Quantifying Vitamin C *****Using the internet research the following: • What is Vitamin C? (composition) • What is the significance (importance) of Vitamin C? Why is it important to us? • What does it do physiologically in the body? • Where can we find Vitamin C? • How can we quantify the amount of vitamin C in food? Identify some reasonable methods that can be used. • Design an experiment that would allow you to accurately quantify the amount of vitamin C in certain foods and factors that change it function. • Make a hypothesis for your experiment.

2. Lab #1-Vitamin C (step 2) • Clarify your research question (what are you looking for or trying to determine?) • Identify variables: • Independent variable amount of vitamin C present. • Dependent variable amount of Vitamin C (titrated) • Controls (standard you will compare with) • Known amount of Vitamin C in the standard (titrate color change) • Room conditions • Titrate coloration • Amount of food being tested • Write a hypothesis • Predictive statement comparing the amount of vitamin C in the foods tested. • List the materials you will need (amount) • Clarify your procedure & generate a data table

3. Vitamin C (Ascorbic acid) • Water soluble • Easily oxidized (loses electrons or H’s) • Plays a key role for producing collagen and norepinephrine in the body. • Body cannot produce it, it must be consumed • Deficiencies cause scurvy, hemorrhage in the gums, joint pain, exhaustion, etc. • Optimum daily intake is debatable (30mg to 2g per day) • Excess can damage kidneys –excreted in urine • Sources: Fruits, vegetables, and organ meats (liver) • Exposure to air, soaked or boiled in water decreases its activity

4. Need to compare the unknown solution with a known solution of vitamin C: “Standard Solution” • Vitamin C content of the standard solution is: 500 mg Vit. C • 1000 ml solution • Key point: You need to know how many drops of the standard it takes to neutralize 5 ml of DCIP from blue color to colorless.

5. Guidelines/Procedure for Lab #1 • Day 1: Develop standard and determine the amount of ascorbic acid in three unknown solutions • Day 2 (Mon.): Bring in items you would like to test and compare. These items can be treated in various ways such as steamed, boiled, or soaked in water if you wish. Depends on what you want to analyze.

6. Key point: You need to know how many drops of the indicator solution it takes to neutralize the known standard solution and determine the volume (ml) that the number of drops represents.

7. Calculations • To determine Vitamin C amount in each juice do the following calculation: (# drops standard soln.)(500mg/1000ml) = (# drops unknown soln. being tested)( ? mg/1000 ml)  • Calculate for three unknown solutions using the equation above. ****Remember: If the unknown solution is more concentrated than the standard, then it should take fewer drops to neutralize the 5ml of DCIP.

8. Sample Data from Day 1 Sample Avg. # drops Calc. Concen. Actual Values (# drops standard soln.)(500mg/1000ml) = (# drops unknown soln.)(? mg/1000 ml)  %Error = Experimental – Actual X 100 Actual

9. Poss. Topics that can be explored • Factors that are important in decomposition of ascorbic acid ie. • Ex. Heat (boiled, steamed, soaked in water) • Determine the effects of different food preparation methods on ascorbic content • Differences in ascorbic acid content in various parts of a fruit or vegetable. • Compare different brands of frozen fruit juices for ascorbic acid content.

10. Completing Your Lab Report • Title that clearly describes what you are investigating. • Clear purpose/problem for this experiment-research quest. • Hypothesis: Be sure it is a clear statement of what you predict. You should include your “reasoning” or basis for this prediction. • State what the dependent and independent variables are • Detailed description of the procedure (method) with all materials used in the experiment. Figs, picts, and drawings are always good. • Clear and Organized Data table. Be sure it is neat with units clearly written for all columns. (uncertainties & sig. figs) • Analysis: requires statistical analysis and presenting your results with graphs, charts, and calculation you made using the standard as a comparison. • Conclusion & Evaluation

11. Conclusion & Evaluation • Written summary that states whether you support your original hypothesis or not. Include reasons for your decision with final results of your experiment. • Evaluate the lab and the procedures taken by identifying all sources of error. • Explain how this experiment can be improved and what you would do differently given our resources.

12. Format & Headings for Lab Report (IB Style)—Must be handwritten • There are (5) criteria with three aspects each (handout) • Design (D) • Defining the problem & selecting variables • Controlling variables • Method for data collection (procedure) • Data Collection & Processing (DCP) • Recording data w/uncertainties & and units (tables) • Processes data appropriately (statistical analysis) • Presents data with graphs & charts w/errors & uncertainties • Conclusion & Evaluation (CE) • Justifies conclusion based on data interpretation (hypothesis revisited) • Evaluate weaknesses & limitations (key sources of error) • Realistic improvements on these weaknesses **Manipulative skills (overall work ethic in the class)--- (MS) **Personal skills (group 4 project working w/others)--- (PS)

13. Key Headings for your Report • Title (needs to be specific for YOUR experiment • Introduction/Background research • Design (3 aspects)** • Data Collection & Processing (3 aspects)** • Conclusion & Evaluation (3 aspects)** **Note: please use the handout for specific sub headings for each criteria DUE: Tuesday, September 16, 2008