An analytical chemist was directed to collect razor clams from a heavily-contami

Question

An analytical chemist was directed to collect razor clams from a heavily-contaminated river superfund site and analyze them for cadmium (Cd^2+) content using graphite furnace atomic absorption spectrometry (GFAAS). The chemist dried the clams at 95 degree C overnight and ground them in a scientific blender for preparing homogenized dry samples. A representative sample was taken from the homogenized dry material and dissolved in 100.00 mL of 0.1 t to create a sample solution. Using the method of standard additions the chemist prepared five standard solutions in 100.00-mL volumetric flasks, each containing 5.00-mL aliquots of the sample solution. Varying amounts of a 92.0 ppb (mu g/L) cadmium standard were added to each of the flasks, which were then brought to volume with 0.1 M HCI The solutions were Then examined for their Cd^2+ content using GFAAS and the following graph was obtained.

Explanation / Answer

Cd analysis

Calculate concentration of Cd standard in dilute solution

with 2.5 ml Cd std added to make 100 ml total volume

final concentration of Cd std in solution = 92 ppb x 2.5 ml/100 ml

                                                               = 2.3 ppb

let Cx be the concentration of Cd in unknown 5 ml solution.

Cx/(Cx + 2.3) = 0.08/0.119

0.119Cx = 0.08Cx + 0.184

Cx = 0.184/0.039

     = 4.72 ppb in 5 ml sample

So, in 100 ml original soltuion

concentration of Cd = 4.72 x 100/5

                        

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.