Question

We are testing for the presence of water-soluble “phenolites” (MM=320 g/mole) in potatoes. We know that phenoliteshave a molar extinction coefficient of 25,000 in a 1 cm light path. We extract 10 g of mashed potatoes in 50 mLof H20, and filter the extract to obtain aclear solution. We then dilute this solution 1:10 (1 mLof extract + 9 mLwater) and read the absorbance on a spectrophotometer (Abs = 0.5). We do not have a standard for phenolitesfrom which to run a standard curve. Calculate the concentration of phenolitesin this mashed potatoes and express the data in molar concentration in ppm

Answer 1

use the Beer-Lambert law: \(Abs=\epsilon*l*[phenolites]\)

plug in your values and solve. Convert Molarity to ppm as they asked.