How do you calculate the concentration (ppm) if you have:

the amount of total solution (60 ml)
the amount of sample that is added to the solution (15 uL)
the density (0.904 g/mL)

Sorry I took so long.

I guess I didn't explain what I wanted very well. ppm comes in three flavors; i.e., w/w, w/v, and v/v. You have volume and volume so you can get ppm v/v from your numbers. Since you give the density I assume you want w/v; you want to convert the 15 uL to a weight(Mass).
So you have 15 uL (0.015 mL) with a density of 0.904 g/mL.
mass = volume x density = 0.015 mL x 0.904 g/mL = 0.0136 g per 60 mL.
ppm in w/v is g/1,000,000 mL so we convert 0.0136 g/60 mL this way.
0.0136 g x (1,000,000/60) = 227 ppm. Another way, which I find simpler is you have 15 uL/60 mL which is 0.015 mL and time density is 0.0136 g or 13.6 mg/60 mL or 13.6/60 = 0.227 mg/mL or 227 mg/L and since 1 ppm is 1 mg/L that is 227 ppm. Two definitions to keep in mind are
1 ppm = 1 mg/L or 1 ug/mL. Then I just convert whatever I have to mg/L and that's the ppm.

Thanks a lot! this make so much sense!!

To calculate the concentration of the sample in parts per million (ppm), you need to determine the mass of the sample added to the solution and then relate it to the total mass of the solution.

Here are the steps to calculate the concentration (ppm):

Step 1: Convert the volume of the sample added to the solution to milliliters (mL). In this case, you have 15 uL, which is equal to 0.015 mL. (1 mL = 1000 uL)

Step 2: Calculate the mass of the sample added to the solution. You can do this by multiplying the volume (in mL) by the density. Using the given density of 0.904 g/mL, the mass of the sample added is 0.015 mL * 0.904 g/mL = 0.01356 g.

Step 3: Calculate the concentration in ppm by dividing the mass of the sample added by the total volume of the solution and multiplying the result by 1 million. The formula is:

Concentration (ppm) = (mass of sample / total volume of solution) * 1,000,000

In this case, the total volume of the solution is given as 60 mL. The concentration is:

Concentration (ppm) = (0.01356 g / 60 mL) * 1,000,000 = 225.6 ppm

Therefore, the concentration of the sample in parts per million (ppm) is 225.6 ppm.