An analyst needs to prepare a standard of fentanyl for a toxicological analysis. The standard is supplied as a powder of fentanyl citrate. The formula weight of the citrate salt is 528.6 g/mol and the formula weight of fentanyl alone is 336.5 g/mole. The analyst is preparing 100.0 mL of the standard at a concentration of 250 ppm (mg/L). How much powder will they have to weigh out to make this standard?

Question

Quizplus · Accepted Answer

To prepare the standard of fentanyl at a concentration of 250 ppm (mg/L), we need to use the following formula:

mass = (concentration x volume x formula weight of fentanyl) / formula weight of fentanyl citrate

mass = (250 mg/L x 100.0 mL x 336.5 g/mol) / 528.6 g/mol

mass = 39.3 mg (rounded to one decimal place)

Therefore, the analyst would need to weigh out 39.3 mg of the fentanyl citrate powder to prepare the standard. Hence, the correct answer is D.

An Analyst Needs to Prepare a Standard of Fentanyl for a Toxicological