ANALYSIS OF THE EXACT AMOUNT

ANALYSIS OF THE EXACT AMOUNT OF FERROUS IRON AVAILABLE IN IRON SUPPLEMENT TABLETS.

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Introduction.

Learning about standardization redox reactions using substances such as potassium permanganate or potassium dichromate in determining the amount of substances really triggered my interest in determining the amount of ferrous iron in iron supplement tablets. This was basically because iron is very important element in many organisms. It is a vital component of the haemoglobin, which is an erythrocyte conjugate protein that transports oxygen absorbed in the lungs through the alveoli to the various tissues of the organisms` body. In addition, it supplies the oxygen required by body muscles since it is a component of myoglobin. Other than facilitating the transport of oxygen in the body tissues and muscles, iron is very essential to other metabolic processes of the body such as the growth and development process, cellular functions, manufacture of various hormones, enzymes and connective tissues of the body.

The deficiency of this element in the body also triggered me to push for this experiment as it leads to various conditions of the body such as anemia, which is a condition where the deficiency of the iron results in less transfer of oxygen to the body tissues in organisms. This condition causes fatigue since there is not enough oxygen in the body to be transported by the haemoglobin (Centers for disease control and prevention, 2011). This could lead to a serious case of immune deficiency because if the brain`s functionality suffers from deficient amounts of oxygen, it weakens the immune system and one becomes exposed to very many infections (Webmed, 2011).

All organisms regardless of their age and gender require iron on their bodies. Nevertheless, women require more amounts of the iron as compared to the male gender because they lose huge pints of blood every month as a result of menstruation process (Heart and Stroke Foundation, 2015). For this reason, the women aged 19 to 50 are advised by the NHS (2015) to ingest about 14.5 mg of ferrous iron per day whereas men are advised to have about 8.0mg of ferrous iron per day. This ingestion is not necessarily through iron supplements but also through foods rich in iron such as green vegetables such as spinach, dry fruits, beans, fortified cereals and red meat such as the liver. These are the best sources of iron however, tablets may be ingested to boost the iron levels if one has been confirmed to have low iron amounts in their body system (National Institute of Health, 2015). Eating foods rich in the iron will therefore decrease the effects caused by the iron deficiency and one may start getting better.

Given the importance of the iron in the organisms` systems, I dived into the research of the amount of iron in the iron supplements taken by people with reduced iron amounts in their bodies and see if these amounts were sufficient to boost their iron amounts with time.

I live in Norway and the state has restrictions with its tablet policies and hence, the directed my choice to using three 100mg iron tablets since that is what was available in the pharmacy.

Investigation.

Reaction under Study.

MnO4 + 8H+ + 5Fe2+ Mn2+ + 4H2O + 5Fe3+

Background of the Reaction.

According to Collin College (2010), reduction oxidation (Redox) reactions are the type of chemical reactions that involve electron transfers between the species present. Titrations on the other hand are done with solutions of known volume with solutions of unknown volumes and concentrations, in order to determine the concentrations of the unknown when the titration reactions react completely. The iron amounts in the tablets are determined by analysis using the redox titration reactions.

Ferrous iron can oxidize to ferric iron in presence of potassium permanganate solution in acidic conditions. The manganese (IV) oxide in the potassium permanganate can also be reduced to manganese (II) ions in the reaction process (Braemar College, 2015).

MnO4 + 8H+ + 5Fe2+ Mn2+ + 4H2O + 5Fe3+ (The manganite ion in the manganese (IV) oxide accepts the electrons from the ferrous iron and is reduced to manganese (II) ions).

The potassium permanganate solution is a deep purple solution and hence, the reaction will not require an indicator to indicate the color change since the potassium permanganate solution will turn from the deep purple color to a pale pink color of manganese (II) ions after the reduction process and the oxidation of the ferrous iron to ferric iron has taken place in acidic conditions. This is advantageous of the potassium permanganate as compared to other titrants (Northern Virginia Community College, 2014). The pink color is often too pale that it can be confused for a colorless solution color. The point where the pale pink color immediately forms in the reaction is the end point of the reaction and that particular titrant volume is the actual volume measurement required for calculations of the amount of iron present. The acid used in this reaction is useful in the provision of the hydrogen ions necessary to facilitate the reaction progress to the end point (Winona State University, 2010). Without the acidic conditions the reaction will not occur.

Calculations.

In order to obtain the amount of iron in the iron supplements, the potassium permanganate is put in the burette and the sulphuric acid mixed with a volume of the tablet solution is put in the conical flask and titrated with the potassium permanganate (Boundless, 2014). The titration proceeds until the appearance of a pale pink solution from the deep purple potassium permanganate color. This titer volume is recorded and is the one that will be used in the calculations. For accuracy, the titration is done at least three times and the titer average volume is obtained. Using the stoichiometric equation of the redox reaction, the moles of the potassium permanganate used, and its volume and the titer average volume of the iron tablets solution obtained, the concentration of the iron in the tablets can be obtained. The results of the amounts of the ferrous iron present in the supplement tablets are then compared against each other are compared in a graph to determine which of the tablets had a high amount of the ferrous iron. The critical part of the experiment involves the titration part. The determination of the change of the color from the deep purple solution to the pale pink color is the critical point of the experiment because the titer volume obtained should be accurate in order to obtain correct amounts of the iron at the end of the experiment. Also, the amounts of tablets used to make the solution to be titrated is vital and any wrong mixing in this section would affect the titration by not turning the potassium permanganate color to pale pink color.

Variables

In this experiment, the concentration of the ferrous iron is dependent on the volume of the titer used. Therefore, the dependent variable is the concentration of the ferrous iron in the supplement tablets whereas the independent variable is the titer volume from the titration. The reaction is done at room temperature and constant pressure and no catalysts are required for the experiment.

Method.

Apparatus Used.

– 0.005M Potassium Permanganate – Burette and Clamp – Conical Flask

– 5 250ml Beakers – Sulphuric Acid – Magnetic Stirrer

– 250ml Volumetric Flask – Distilled Water – Mortar and Pestle

– Ferromax 65mg Tablets – Duroferon 100mg Tablets – Nifrex 100mg Tablets

– Nycoplas Ferro-Retard 100mg Tablets – Hemofer (2 tablets) 27mg – Haemoglobin from a cow.

Photographs of the Experiment.

Photograph showing the iron solution made from the Hemofer tablets.

Photograph showing the iron solution of the Nycolplus Ferro-Retard Tablets.

Photograph showing iron solution of the Dureferon tablets

Photograph showing the deposition of the iron clusters formed on the filter paper after filtration of the iron solution.

Photograph showing the iron solution formed from the Ferromax 65mg tablets.

Photograph showing the iron solution mixture of the Nifrex 100mg tablets.

Photograph showing the deposition of the iron clusters formed at the bottom of the volumetric flask containing the iron solution.

Experimental Procedure.

Preparation of the Iron Sample Solutions.

The beakers were cleaned with soap and water and rinsed severally with distilled water in order for them to be totally clean. The tablets of each of the supplements: 65mg of the Ferromax, 100mg of the Dureferon, 100mg of Nifrex, 100mg of Nycoplus Ferro-Retard and 27mg of the Hemefer were put in the beakers. Distilled water was thereafter added to each of the sample to dissolve each of the samples. The solids were stirred to aid in the dissolution. 8ml of the 3M sulphuric acid was thereafter added in order to provide the hydrogen ions that were required for the reduction of the potassium permanganate.

Titration Redox Reaction procedure of the Potassium Permanganate and the Iron Solution Formed.

The burette was cleaned and rinsed using distilled water. Afterwards, it was filled with the potassium permanganate solution to the 0 ml mark. Each of the samples were then titrated to their endpoints and the titer volumes were thereafter recorded. The mass of the iron in each of the samples were thereafter determined from the obtained titer volumes using the stoichiometric equation of the reaction that happened.

Risk Assessment.

Safety Considerations.

Potassium Permanganate

Weak concentrations of the potassium permanganate were used and regardless of the concentration, the reagent is not hazardous.

Sulphuric Acid.

The concentration used is high and thus there is a risk for irritating the eyes and the skin. In addition, severe burns to the eyes, skin and body tissues are risks associated with the 3M sulphuric acid (Risk assessment services, 2008). Wearing safety googles and protective gloves and a laboratory coat, keeping the reagent in ventilated places and out of reach of children are some of the prevention measures taken to reduce the risk associated with the reagent.

In case of contact with the acid to the skin, the acid should be washed immediately with running water and thereafter seek medical advice. In case of ingestion of the acid, artificial respiration is applied, and medical help is sought immediately.

Avoid contact of the acid with water because the acid will react with the water explosively producing fumes. The acid should be washed down the sink with large amounts of water and in case of spillage, any sand adsorbent can be used to dry it out and the adsorbent disposed of as contaminated waste. Proper handling of the acid reduces the risks associated with the sulphuric acid.

Iron Supplements

These reagents are not hazardous.

Distilled Water.

The water is not hazardous. However, it should not be used for drinking.

Environmental Concentrations.

Sulphuric acid reacts with most of the metals and hence would cause a depletion of important minerals of the lithosphere if not well disposed. Hence proper disposal of the sulphuric acid should be done (Risk assessment services, 2008).

Ethical Considerations.

There were no ethical considerations to be accounted for in this experiment.

Experimental Results and Calculations.

Final Volume in ml 84.0 82.0 78.0
Initial Volume in ml 0.0 0.0 0.0
Titer volume in ml 84.0 82.0 78.0

The results for the Hemofer 27mg tablets.

Mass before = 40.220g and after mass = 40.174g

MnO4 + 8H+ + 5Fe2+ Mn2+ + 4H2O + 5Fe3+

The reacting mole ratio is 1:5

The titer average is (84.0 + 82.0 + 78.0)/ 3 = 81.33 ml.

1000 ml KMnO4 = 0.005moles

81.33 ml =?

81.33/1000 × 0.005 moles = 0.00040665moles

Moles of the iron that reacted are 0.00040665 × 5 = 0.00203325moles.

1mole Fe = 56g

0.00203325moles =?

0.00203325/1 × 56g

= 0.113862g Ferrous Iron.

This was greater than the amount of the iron written on the tablet by 0.086862g since

250ml = 0.27g

25ml = 25/250 × 1 = 0.027g.

Final Volume in ml 86.0 73.0 88.0
Initial Volume in ml 0.0 0.0 0.0
Titer Volume in ml 86.0 73.0 88.0

The results shown are for the Nifrex 100mg tablets. The mass before = 39.597g and the mass after = 39.494g.

MnO4 + 8H+ + 5Fe2+ Mn2+ + 4H2O + 5Fe3+

The reacting mole ratio is 1:5

The titer average is (86.0 + 73.0 + 88.0)/ 3 = 82.33ml

1000 ml KMnO4 = 0.005moles

82.33 ml =?

81.33/1000 × 0.005 moles = 0.00041165moles

Moles of the iron that reacted are 0.00041165 × 5 = 0.00205825moles.

1mole Fe = 56g

0.00205825moles =?

0.00203325/1 × 56g

= 0.115262g Ferrous Iron.

This was greater than the amount of the iron written on the tablet by 0.015262g since

250ml = 1g

25ml = 25/250 × 1 = 0.10g.

Final volume in ml 24.0 23.0 46.2 22.8 45.5 23.5
Initial Volume in ml 0.0 0.0 23.0 0.0 0.0 0.0
Titer Volume in ml


24.0 24.0 23.2 22.8 22.7 23.5

The results shown represent those obtained from the Ferromax Tablets. The mass before = 37.505g and the mass after = 37.434g.

MnO4 + 8H+ + 5Fe2+ Mn2+ + 4H2O + 5Fe3+

The reacting mole ratio is 1:5

The titer average is (24.0 + 23.0 + 23.2 + 22.8 +22.7 + 23.5)/ 5 = 27.84 ml.

1000 ml KMnO4 = 0.005moles

27.84 ml =?

27.84/1000 × 0.005 moles = 0.0001392moles

Moles of the iron that reacted are 0.0001392 × 5 = 0.000696moles.

1mole Fe = 56g

0.000696moles =?

0.000696/1 × 56g

= 0.038976g Ferrous Iron.

This was lesser than the amount of the iron written on the tablet by 0.026024g since

250ml = 0.65g

25ml = 25/250 × 1 = 0.065g.

Final Volume in ml 75.0 68.0 87.0
Initial Volume in ml 0.0 0.0 0.0
Titer Volume in ml 75.0 68.0 87.0

The results obtained are for the Nycoplus Tablets. The mass before = 38.454g and the mass after = 38. 405g

MnO4 + 8H+ + 5Fe2+ Mn2+ + 4H2O + 5Fe3+

The reacting mole ratio is 1:5

The titer average is (75.0 + 68.0 + 87.0)/ 3 = 76.67 ml.

1000 ml KMnO4 = 0.005moles

76.67 ml =?

76.67/1000 × 0.005 moles = 0.000383335moles

Moles of the iron that reacted are 0.00038335 × 5 = 0.00191675moles.

1mole Fe = 56g

0.00191675moles =?

0.00191675/1 × 56g

= 0.107338g Ferrous Iron.

This was greater than the amount of the iron written on the tablet by 0.007338g since

250ml = 1g

25ml = 25/250 × 1 = 0.10g.

Final Volume in ml 64.0 68.0 74.0
Initial Volume in ml 0.0 0.0 0.0
Titer Volume in ml 64.0 68.0 74.0

The results obtained are for the Dureferon Tablets. The mass before = 38.561g and the mass after = 38. 521g.

MnO4 + 8H+ + 5Fe2+ Mn2+ + 4H2O + 5Fe3+

The reacting mole ratio is 1:5

The titer average is (64.0 + 68.0 + 74.0)/ 3 = 68.67 ml.

1000 ml KMnO4 = 0.005moles

68.67 ml =?

68.67/1000 × 0.005 moles = 0.00034335moles

Moles of the iron that reacted are 0.00034335 × 5 = 0.00171675moles.

1mole Fe = 56g

0.00171675moles =?

0.0017167/1 × 56g

= 0.096138g Ferrous Iron.

This was lesser than the amount of the iron written on the tablet by 0.003862g since

250ml = 1g

25ml = 25/250 × 1 = 0.10g.

The figure above shows the amount of the iron content in the tablets as per the results.

Discussion and Conclusion.

The results from the experiment differ from the data written on the tablets for the amount of ferrous iron contained in each tablet. The deviations were very huge values of milligrams and the results clearly indicated many errors present in the experiment. One of the main reasons why the values of the experiment are very inaccurate would be most especially since the titer volumes of the supplement tablets were wrong as the potassium permanganate end point of a pale pink solution was not achieved for most of these tablets except for the ferromax tablets. Without the correct titer volumes, the correct amount of the iron in the supplement tablets would therefore not be obtained accurately.

The main reason for the error in the experiment would have been that the ferrous iron to be oxidized by the potassium permanganate was in small amounts in the iron solution from the tablets. This could have been attributed by the fact that the ferrous iron is easily oxidized by the air in the atmosphere to ferric iron which is dark red in color and therefore, no reaction occurs between the ferric oxide and the potassium permanganate, and for this reason the pale pink manganese (II) ions will not be formed. Rather, the potassium permanganate solution retains its deep purple color. With this error, the titer volume can therefore not be obtained.

According to Collin College (2010), to avoid the premature oxidation of the ferrous iron to ferric iron, the use of the Jones redactor could be incorporated into the solution in order to convert any ferric iron back to the ferrous state in order for the redox reaction to proceed and an end point is obtained. The Jones redactor consists of a column filled zinc coated with mercury. Besides this, tin (II) chloride can also be used for the same purpose (Chemistry Lab Mouse A2, 2008).

2FeCl3 + SnCl2 SnCl4 + FeCl2

Another source of error would have been as a result of the potassium permanganate used in the experiment since the reagent is not usually stable and should be checked frequently by the lab technicians to normalize it. The permanganate used may also have not been normalized in a while and hence, making the detection of the end point difficult. Thus, the results got altered because of this.

In conclusion, the amounts of the iron in the supplement tablets were obtained. However, the amounts detected deviated from the actual amounts of iron indicated on the tablets and this was as a result of the experimental error where the ferrous iron oxidized to ferric iron and hence the redox titration reaction could not occur since ferric iron is stable and cannot reduce potassium permanganate. For this reason, the titer volumes obtained were wrong and so were the determined amounts of the iron from the supplement tablets. As discussed in future experiments, one should be really careful with the iron solution and add the Jones redactor to convert any converted ferric iron back to the oxidizable ferrous iron.

References

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 Collin College. (2010). Determination of Iron in Dietary Supplement through Redox Titrations [Online] Available from:  http://www.collin.edu/chemistry/Handouts/1412/Redox Titration Experiment.pdf> [Accessed 27 February 2019].

Heart and Stroke Foundation. (2015). Nutrients for women [Online] Available from:  http://www.healthcheck.org/page/nutrients-women> [Accessed 27 February 2019].

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NHS. (2015). Vitamins and Minerals- Iron [Online] Available from:  http://www.nhs.uk/Conditions/vitamins-minerals/Pages/Iron.aspx [Accessed 27 February 2019]. 

Northern Virginia Community College. (2014). Chemistry 111 Lab- Redox Titration [Online] Available from:  http://www.nvcc.edu/alexandria/stb/chm/111/111.08RedoxTitrationSpring2015.pdf [Accessed 27 February 2019].

Risk assessment services. (2008. Hazard Communication Sheet Sulphuric Acid 90-100%w/w [Online] Available from:  http://www.riskassessmentservices.co.uk/HazCom/Sulphuric Acid3.pdf> [Accessed 27 February 2019].

Webmed. (2011). What You Need to Know About Iron Supplements [Online] Available from:  http://www.webmd.com/vitamins-and-supplements/lifestyle-guide-11/iron-supplements?page=3 [Accessed 27 February 2019].

Winona State University. (2010). Determination of Iron by Redox Titration [Online] Available from:  http://course1.winona.edu/cmiertschin/213/inquiry_lab/exp10_fe_redox.pdf [Accessed 27 February 2019].