• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Quantitative Analysis of Vitamin C in Food Products.

Extracts from this document...

Introduction

Quantitative Analysis of Vitamin C in Food Products Theory Review There is growing evidence that Vitamin C serves as a potent antioxidant in vitro. There are many functions that Vitamin C has in the body among which is the capacity to improve the immunity system such that a person is more able to fight off colds and flus. Pre-Lab: List five other functions of Vitamin C in the human body. Vitamin C is another name for ascorbic acid. There is a marked similarity between the structure of glucose and Vitamin C. As a matter of fact, plants and most animals are able to synthesize Vitamin C from glucose. Unfortunately, humans are unable to do this and we must include Vitamin C in our diet or we risk a vitamin deficiency disease. ...read more.

Middle

One useful analytical method for measuring the Vitamin C content of a vegetable or fruit involves an oxidation-reduction titration of ascorbic acid. In the titration, ascorbic acid is oxidized to form dehydroascorbic acid. You might think it unusual to oxidize the acid rather than titrate it with a base. However, biological samples contain many substances that also act as acids (as was mentioned in Experiment 3) and thus interfere in a titration of ascorbic acid with a base. In contrast, many fewer components of biological materials interfere with the oxidation of ascorbic acid by the oxidizing agent 2, 6-dichloroindophenol (DCP). Thus, an oxidation-reduction titration of ascorbic acid with DCP provides a more selective analysis than would an acid-base titration. ...read more.

Conclusion

We can perform the standardization conveniently by titrating aliquots of an ascorbic acid solution prepared from an accurately-weighed sample of reagent-grade ascorbic acid. The standardization titration reaction is the same as the analysis reaction above. In this experiment, you will begin by standardizing a DCP solution. Then you will determine the vitamin C content of liquid and solid food samples by titration with the standardized DCP solution. Prior to performing the titrations, you will treat the food samples with metaphosphoric acid. Treatment with this acid serves to denature and precipitate proteins that would otherwise interfere with the analysis. Acidification of thesample also serves to stabilize the ascorbic acid, which will otherwise decompose and be undetectable. Acidification to pH less than 4 also minimizes reaction of DCP with other compounds which react with DCP only at pH levels greater than 4. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Physical Chemistry section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Physical Chemistry essays

  1. Drug: Antacid Effectiveness Analysis To determine the neutralizing ability of antacids in different ...

    of moles of HCl neutralized by 1 tablet: 0.71g � 0.00692 mol g-1 = 0.00491 mol Vol of HCl neutralized by 1 tablet = 0.00491/0.1= 0.0491dm3 = 49.1cm3 Vol/ mass = 49.1/0.71= 69.2 cm3/g Results: Brand name Vol. of HCl neutralized/ mass (cm3/g)

  2. Analysis of commercial vitamin C tablets

    Na2S2O3 solution:- Trial 1st 2nd Final reading /cm3 12.70 26.90 14.80 Initial reading /cm3 0.60 14.60 2.55 Volume of Na2S2O3 /cm3 12.10 12.10 12.25 Average volume of Na2S2O3 added /cm3 12.175 Mass of vitamin C in a tablet (manufacturer's specification): 1 g Mass of a vitamin C tablet: 4.54 g No.

  1. Determination of the content of Mg (OH)2 in an indigestion remedy by back titration ...

    Therefore, theoretically a weak acid (fewer H+ ions in solution) reacted with a strong base(NaOH) an indicator such as Methyl Red would have been more appropriate and would given a better indication as to when equivalence(endpoint) was reached (pH 4.2-6.3)9.

  2. Aim:To investigate the content of vitamin C (ascorbic acid) content in a commercial tablets ...

    of moles of I2 formed = 3.03710-3 3 = 9.112 10-3mol 2S2O32- + I2 --> S4O62- + 2I- No. of moles of I2 used in 25 cm3 solution = 9.112 10-4 mol No. of moles of Na2S2O3 used = 9.112 10-4 2 = 1.8224 10-3 mol Molarity of the given

  1. Investigating the Rate of the Reaction between Bromide and Bromate Ions in Acid Solution

    53 311 53 310 316 44 314 43 314.5 45 314 321 32 323 31 322 24 323 29 323 (Table 3.4.2) 3.5 - Analysis of Results of Varying the Concentration of the Reactants From varying the concentration of each reactant in turn, I can determine the order of the

  2. Acid-Base Titrations.

    In the course of the calculations and discussion, we will answer such questions as the titrant to use, the indicator to select, and what manner of solution is present at various points along the titration curve. First, consider the titrant solution.

  1. Analysis of commercial vitamin C tablets

    Trial 1 2 Final reading 34.20 48.70 14.90 Initial reading 19.60 34.20 0.50 Volume of titrant used 14.60 14.50 14.40 Average titrant used = (14.50+14.40)/2 =14.45 cm3 Questions 1. Calculate the concentration of the give sodium thiosulphate solution. No. of mole of KIO3 titrated = [0.6808/(39.1+126.9+16x3) ]/10 =(0.6808/214)/10 =0.0003181308411mol ?No.

  2. Methods of analysis and detection

    So how to Determine the % composition of a mixture by GLC: The area of a peak = 1/2 (Base � Height) Therefore, a chromatogram must show all the components and the detector are respond equally to all components. Green Tea Separation in GLC ?

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work