INAC PROJECT'13

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INAC PROJECT'13

Project Title:

Fluoride Concentration in Various Brands of Toothpaste

What Is It About?

Toothpaste that contains fluoride can help to prevent cavities. However, too much fluoride might not be good for our health.

This blog will talk about the pros and cons of using fluoridated toothpaste, and also on how fluoride concentrations of various brands of toothpaste are determined.

Materials and Methods

Monday, 29 July 2013

List of Materials

Orion Bench Top pH/ISE meter with fluoride ion-selective electrode(ISE)
Analytical-reagent grade chemicals
Distilled water
Sodium fluoride (NaF; USP reference standard)
Na4EDTA.2H2O tetra sodium ethylene diamine tetra acetic acid
Sodium hydroxide
Sodium acetate tridydrate
Concentrated HCl
6 toothpaste samples (Sample 1, Sample 2, Sample 3, Sample 4, Sample 5, Sample 6)
Desiccator (an airtight box or jar containing a desiccant, used to dry chemicals and protect them from the water vapour in the atmosphere)
Plastic volumetric flask
Plastic funnel
Plastic beaker
Stirrer

Methods (Chemicals Preparation)

1. Prepare 1000µg/ml Fluoride stock solution. Dry Sodium fluoride (USP Reference Standard) for 4 hours at 150°C and then cool it in a desiccator before use. Store the fluoride stock solution in a plastic volumetric flask.

2. A first stock standard solution of approximate F- concentration of 100ppm was prepared from which 1, 5, 50ppm working standards were made for the standardization of the ISE.

3. A check standard of 5ppm was then prepared from a second 100ppm stock standard.

4. Ionic strength(IS) diluent was prepared from 100g of Na4EDTA.2H2O tetra sodium ethylene diamine tetra acetic acid 15g of sodium hydroxide and 100g of sodium acetate tridydrate in a volume of 1000ml.

5. The pH of the IS diluent was adjusted to pH7.25[± 0.03] using concentrated HCl. When the IS reagent is used, the concentration of fluoride rather than its activity is measured.

Methods (Sampling)

6. 6 samples of toothpaste (both adult and paediatric) from different manufacturers and countries are selected in this experiment.

7. Accurately weigh 5g of Sample 1 into a 150ml plastic beaker and add 39.0ml of water.

8. Add 11.0ml of concentrated HCl. Cover the beaker and stir for at least 1 hour.

9. Cool the solution to room temperature and then transfer the mixture to a 250ml plastic volumetric flask with a plastic funnel.

10. Dilute mixture to mark with the NAIS Diluent.

11. Repeat Steps 7 to 10 for the other 5 samples.

**THINGS TO NOTE**

Check the pH of the sample prepared. The pH value should fall within 0.5 unit of that of the 5ppm working standard solution. The sample must be re-prepared if its pH is not within the range of 6.5 to 8.0.

The reading (R) in ppm for each sample was determined in duplicate with the ion-meter and the total fluoride concentration in ppm was calculated using the formula:

[F-] = R x 250/W

Where [F-] is the total fluoride concentration (ppm)

R is the reading for sample off the instrument (ppm)

W is the weight of sample (g)