A stock solution of analyte is made by dissolving 34.83 mg of
copper (II) acetate
hexahydrate (fw = 289.73 g/mol) in 25.000 mL of water. A second
stock solution of internal
standard is made by dissolving 28.43 mg of germanium (I) acetate
(fw = 190.74 g/mol) into
25.000 mL of water. These solutions are used to make a series of
standards for flame atomic
absorption analysis calibration. The standard solutions (each 10.00
mL total volume) should
have the following concentrations of copper: 10.00; 25.00; 50.00;
100.0; and 200.0 μM. Each
calibration solution should also contain 50.00 μM of germanium.
Based on this information,
complete the following:
Stock solution concentration (analyte): ______________________
Stock solution concentration (internal standard): ______________________
Concentration Cu (μM) |
Volume of analyte stock (mL) |
Volume of internal standard stock (mL) |
Volume of diluent (mL) |
Total Volume (mL) |
10.00 | 10.000 | |||
25.00 | 10.000 | |||
50.00 | 10.000 | |||
100.0 | 10.000 | |||
200.0 | 10.000 |
I. Stock Solution prepared via Copper acetate hexahydrate (289.73g/mol) in 25mL of water
Molarity of Copper acetate solution M1= W*1000/molar mass *Volume
= 34.83*10-3*1000/289.73*25
= 0.0048 M ~0.005M
II. Internal standard stock solution is prepared via germanium acetate (190.74 g/mol) in 25mL of water
Molarity of Germanium acetate solution M2= W*1000/molar mass *Volume
= 28.43*10-3*1000/190.74*25
= 0.0059 M ~0.006 M
Dilution:
A) 50 µM germanium acetate as internal standard has to be add in all solutions therefore,
0.0059*X(vol)=50*10-6*10
X=5*10-4/0.0059= 0.0847 mL or 84.7µL internal standard stock has to be added in each tube.
B) Copper acetate stock’s calculation for dilution
M1V1=M2V2 (M1- Copper acetate stock molarity, V1- required amount for specific concentration i.e. M2 and V2- 10 mL)
1) 0.0048* V1=10µM*10
V1=100*10-6/0.0048 = 0.0208 mL or 20.8 µL
2) 0.0048* V1=25µM*10
V1=250*10-6/0.0048 = 0.0520 mL or 52 µL
3) 0.0048* V1=50µM*10
V1=500*10-6/0.0048 = 0.1041 mL or 104 µL
4) 0.0048* V1=100µM*10
V1=1000*10-6/0.0048 = 0.2083 mL or 208.3 µL
5) 0.0048* V1=200µM*10
V1=2000*10-6/0.0048 = 0.5833 mL or 583.3 µL
S.No. |
Cu Conc (µM) |
Volume of analyte (mL) |
Volume of internal standard stock (mL) |
Volume of diluent (mL) |
Total volume |
1 |
10 |
0.0208 |
0.0847 |
9.8945 |
10.000 mL |
2 |
25 |
0.0520 |
0.0847 |
9.8633 |
10.000 mL |
3 |
50 |
0.1041 |
0.0847 |
9.8112 |
10.000 mL |
4 |
100 |
0.2083 |
0.0847 |
9.707 |
10.000 mL |
5 |
200 |
0.5833 |
0.0847 |
9.332 |
10.000 mL |
A stock solution of analyte is made by dissolving 34.83 mg of copper (II) acetate hexahydrate...
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