Real World Project: Determination of Vitamin C in Fruit Juices Brian Gillease And Lauren Burns

Objective Calculate vitamin C in a Vitamin C tablet Titrate fruit juices Calculate amount of vitamin C in each juice Compare juices to tablet

Importance Vitamin C – – antioxidant; binds with carbon, hydrogen, oxygen; oxidizes easily – Safe and efficient nutrient, helps protect body against cardiovascular disease, eye disease, and other diseases

Procedures Standardized thiosulfate solution using a starch paste Titrated a vitamin C tablet with thiosulfate to determine the amount of ascorbic acid present Juiced fruits Centrifuged fruits Titrated with thiosulfate

Procedures - Errors Juicer – too much pulp Filtration – pulp too thick Strawberry Juice – red color of juice

Picture Perfect!

Clementine Juice 30 mL filtered, digested soln mL KIO3 soln. + KI + 10 mL H2SO4 + starch indicator Trial Mass KI (g) Initial Vol. Na2S2O3 (mL) Final Vol. Na2S2O3 (mL) Vol. Na2S2O3 Added Consumed Moles I3- Moles I3- Present Grams Ascorbic Acid% Difference Moles I3- Formed Average Manufacture r's Claim0.176 grams per fruit Data

Clementine Juice Spike 30 mL filtered, digested soln mL KIO3 soln. + KI + 10 mL H2SO4 + starch indicator Trial Mass KI (g) Mass AA (g) Total Mass AA (g) Initial Vol. Na2S2O3 (mL) Final Vol. Na2S2O 3 (mL) Vol. Na2S2O3 Added Consume d Moles I3- Moles I3- Present Grams Ascorbic Acid % Difference E E Moles I3- Formed Average Manufacturer's Claim0.0176

Papaya Juice 30 mL filtered, digested soln mL KIO3 soln. + KI + 10 mL H2SO4 + starch indicator Trial Mass KI (g) Initial Vol. Na2S2O3 (mL) Final Vol. Na2S2O3 (mL) Vol. Na2S2O3 Added Consumed Moles I3- Moles I3- Present Grams Ascorbic Acid % Difference Moles I3- Formed Average Manufacturer's Claim grams per fruit

Papaya Juice Spike 30 mL filtered, digested soln mL KIO3 soln. + KI + 10 mL H2SO4 + starch indicator Trial Mass KI (g) Mass AA (g) Total Mass AA (g) Initial Vol. Na2S2 O3 (mL) Final Vol. Na2S2O3 (mL) Vol. Na2S2O 3 Added Consumed Moles I3- Moles I3- Present Grams Ascorbic Acid % Differenc e E E Moles I3- Formed Average Manufacturer's Claim0.0956

Orange Juice 30 mL filtered, digested soln mL KIO3 soln. + KI + 10 mL H2SO4 + starch indicator TrialMass KI (g) Initial Vol. Na2S2O3 (mL) Final Vol. Na2S2O3 (mL) Vol. Na2S2O3 Added Consumed Moles I3- Moles I3- Present Grams Ascorbic Acid % Difference E Moles I3- Formed Average Manufacturer's Claim grams per fruit

Orange Juice Spike 30 mL filtered, digested soln mL KIO3 soln. + KI + 10 mL H2SO4 + starch indicator Trial Mass KI (g) Mass AA (g) Total Mass AA (g) Initial Vol. Na2S2O 3 (mL) Final Vol. Na2S2O 3 (mL) Vol. Na2S2O 3 Added Consum ed Moles I3- Moles I3- Present Grams Ascorbic Acid % Differenc e E E E Moles I3- Formed Average E Manufacturer's Claim0.0511

Grapefruit Juice 30 mL filtered, digested soln mL KIO3 soln. + KI + 10 mL H2SO4 + starch indicator Trial Mass KI (g) Initial Vol. Na2S2O3 (mL) Final Vol. Na2S2O3 (mL) Vol. Na2S2O3 Added Consumed Moles I3- Moles I3- Present Grams Ascorbic Acid % Difference E Moles I3- Formed Average Manufacturer's Claim grams per fruit

Grapefruit Juice Spike 30 mL filtered, digested soln mL KIO3 soln. + KI + 10 mL H2SO4 + starch indicator Trial Mass KI (g) Mass AA (g) Total Mass AA (g) Initial Vol. Na2S2O3 (mL) Final Vol. Na2S2O3 (mL) Vol. Na2S2O3 Added Consumed Moles I3- Moles I3- Present Grams Ascorbic Acid % Difference E E E Moles I3- Formed Average Manufacturer's Claim0.0384

Strawberry Juice 30 mL filtered, digested soln mL KIO3 soln. + KI + 10 mL H2SO4 + starch indicator Trial Mass KI (g) Initial Vol. Na2S2O3 (mL) Final Vol. Na2S2O3 (mL) Vol. Na2S2O3 Added Consumed Moles I3- Moles I3- Present Grams Ascorbic Acid % Difference Moles I3- Formed Average Manufacturer's Claim grams per fruit

Strawberry Juice Spike 30 mL filtered, digested soln mL KIO3 soln. + KI + 10 mL H2SO4 + starch indicator Trial Mass KI (g) Mass AA (g) Total Mass AA (g) Initial Vol. Na2S2 O3 (mL) Final Vol. Na2S2O3 (mL) Vol. Na2S2O3 Added Consume d Moles I3- Moles I3- Present Grams Ascorbic Acid % Differenc e E E E Moles I3- Formed Average Manufacturer's Claim0.0071

Error Source Over titrated thiosulfate Not enough KI – Wasn’t an excess of KI to react with Refrigerate – Juices were not refrigerated Solutions degrade – KIO 3 degraded; did not work

Conclusion Papaya juice contained the most Vitamin C; aligned with FDA statistics Numerous errors throughout Overall experiment was unsuccessful; several areas that could be improved