Understanding Concentration: Percentage (%) vs. Parts Per Million (ppm)

Concentration can be expressed in various units, including percentage (%) and parts per million (ppm). These units are related, and you can convert between them.

• Percentage (%): Represents parts per hundred. For example, 1% means 1 part of the substance in 100 parts of the total mixture.
• Parts Per Million (ppm): Represents parts per million. For example, 1 ppm means 1 part of the substance in 1,000,000 parts of the total mixture.

Conversion between Percentage and ppm

The conversion factor is:

1% = 10,000 ppm

To convert a percentage to ppm, multiply the percentage by 10,000.
To convert ppm to a percentage, divide the ppm by 10,000.

Calculating Concentrations

Let's calculate the concentrations you asked about:

• How to calculate 1 ppm and 5 ppm?
  1 ppm means 1 part of the substance in 1,000,000 parts of the total. In terms of percentage, this is:
  1 ppm = 1 / 10,000 % = 0.0001%

  5 ppm means 5 parts of the substance in 1,000,000 parts of the total. In terms of percentage, this is:
  5 ppm = 5 / 10,000 % = 0.0005%

• If we use 5%, what will it equal in ppm?
  To convert 5% to ppm, multiply by 10,000:
  5% = 5 * 10,000 ppm = 50,000 ppm

So, using Epidermal Growth Factor (EGF, Recombinant) at a concentration of 5% is equivalent to a concentration of 50,000 ppm.

For reference, the product description for Epidermal Growth Factor (EGF, Recombinant) mentions experiments where EGF was used at concentrations of 1 ppm and 5 ppm to show efficacy in strengthening the skin barrier.