In the Fluorometric analysis of Quinine in Tonic Water Lab Prepare four standard
ID: 928388 • Letter: I
Question
In the Fluorometric analysis of Quinine in Tonic Water Lab
Prepare four standards of 0.15, 0.30, 0.45, and 0.60 g/mL by dilution of the stock standard solution. Start with the lowest concentration standard. Use the appropriate micropipette to introduce 150 L of the stock standard into the volumetric flask and dilute to 10.00 mL with 0.05 M H2SO4. Mix and transfer the solution to a vial. Repeat this process with 300 L, 450 L and 600 L of stock standard.
Note:
- Acidic analysis solution: 0.05 M H2SO4 in distilled water.
- Stock quinine standard: 10 ppm (g/ml) stock solution made in 0.05 M H2SO4.
- Quinine (C20H24N2O2, 324.43 g/mol)
Q: Calculate the actual concentrations of these standards.
Explanation / Answer
Stock quinine standard = 10 ppm = 10 microgram/ml in 0.05 M H2SO4
To prepare the solutions with concentrations of,
0.15 microgram/ml (or ug/ml)
C1V1 = C2V2
with,
C1 = 10 ugram/ml
C2 = 0.15 ug/ml
V1 = ?
V2 = 10 ml
we get,
Volume of standard to be taken V1 = 0.15 x 10/10 = 0.15 ml
Transfer 0.15 ml by a pipetter and dilute to 10 ml by 0.05 M H2SO4
Final concentration of quinine in solution = 0.15 ug/ml
0.30 microgram/ml (or ug/ml)
C1V1 = C2V2
with,
C1 = 10 ugram/ml
C2 = 0.30 ug/ml
V1 = ?
V2 = 10 ml
we get,
Volume of standard to be taken V1 = 0.30 x 10/10 = 0.30 ml
Transfer 0.30 ml by a pipetter and dilute to 10 ml by 0.05 M H2SO4
Final concentration of quinine in solution = 0.30 ug/ml
0.45 microgram/ml (or ug/ml)
C1V1 = C2V2
with,
C1 = 10 ugram/ml
C2 = 0.45 ug/ml
V1 = ?
V2 = 10 ml
we get,
Volume of standard to be taken V1 = 0.45 x 10/10 = 0.45 ml
Transfer 0.45 ml by a pipetter and dilute to 10 ml by 0.05 M H2SO4
Final concentration of quinine in solution = 0.45 ug/ml
0.60 microgram/ml (or ug/ml)
C1V1 = C2V2
with,
C1 = 10 ugram/ml
C2 = 0.60 ug/ml
V1 = ?
V2 = 10 ml
we get,
Volume of standard to be taken V1 = 0.60 x 10/10 = 0.60 ml
Transfer 0.60 ml by a pipetter and dilute to 10 ml by 0.05 M H2SO4
Final concentration of quinine in solution = 0.60 ug/ml
Actual concentrations,
0.15 ug/ml
= 0.15 x 10^-3 mg x 324.43/0.010 = 4.9 x 10^-4 mg/L = 0.49 ppm
0.30 ug/ml
= 0.30 x 10^-3 mg x 324.43/0.010 = 0.97 x 10^-3 mg/L = 0.97 ppm
0.45 ug/ml
= 0.45 x 10^-3 mg x 324.43/0.010 = 1.47 x 10^-3 mg/L = 1.47 ppm
0.60 ug/ml
= 0.60 x 10^-3 mg x 324.43/0.010 = 1.96 x 10^-3 mg/L = 1.96 ppm