An analyst prepares a diluted standard for use in a post-mortem toxicological assay. The analyst dilutes 2.0 uL of a commercial standard, 1.00 mg/mL, to 10.00 mL in a type A volumetric flask. A syringe is used to draw out and deliver the 2.0 uL. The absolute uncertainties of the equipment are:
Volumetric flask: 0.08 mL
Syringe: 0.10 uL
Commercial standard: 0.050 mg/mL
What is the final concentration of the diluted solution in ug/mL? WATCH THE UNITS and report to the correct number of significant figures

Question

Quizplus · Accepted Answer

The final concentration is calculated by using the formula C1V1 = C2V2, where C1 and V1 are the concentration and volume of the initial solution, and C2 and V2 are the concentration and volume of the final solution. Here, C1 = 1.00 mg/mL = 1000 ug/mL, V1 = 2.0 uL = 0.002 mL, and V2 = 10.00 mL. Rearranging the formula to solve for C2 gives C2 = (C1V1)/V2 = (1000 ug/mL * 0.002 mL) / 10.00 mL = 2.00 ug/mL.

An Analyst Prepares a Diluted Standard for Use in a Post-Mortem