To convert milliliters (mL) of a substance to parts per million (ppm), you need to know the density of the substance. However, assuming that the density of your seed extract is similar to that of water (1 g/mL), you can use the following steps:
Convert the volume of the seed extract to mass. If we assume the density of the seed extract is approximately 1 g/mL, then 2 mL of seed extract would have a mass of about 2 grams1.
Convert the total volume of the solution to liters. In your case, you have 100 mL of HCl, which is equivalent to 0.1 liters1.
Calculate the concentration in ppm using the formula: ppm = (mass of solute in grams / volume of solution in liters) * 10^61.
So, for your case: ppm = (2 g / 0.1 L) * 10^6 = 20,000 ppm.
Please note that this calculation assumes that the density of your seed extract is approximately 1 g/mL, and that the seed extract is completely soluble in HCl.