Buchi KjelFlex K-360, Руководство по эксплуатации

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3 Technical data
17
KjelFlex K-360 Operation Manual, Version D
3 .3 Titration solution
The amount of sample and the concentration of the titrant should be optimized, so that the titrant
volume is between 2 and 18 mL (burette volume: 20 mL).
Table 3-5: Titration solution 1
N-amount N-content Sample size Titrant Titrant concentration Titrant volume
5 mg N 0.5 % N 1 g
H
2
SO
4
0.01 mol/L
17.8 mL
10 mg N 1.0 % N 1 g
H
2
SO
4
0.05 mol/L
7.1 mL
50 mg N 5 % N 0.1 g
H
2
SO
4
0.01 mol/L
17.8 mL
100 mg N 10 % N 1 g
H
2
SO
4
0.25 mol/L
14.3 mL
100 mg N 10 % N 1 g
H
2
SO
4
0.5 mol/L
7.1 mL
200 mg N 20 % N 1 g
H
2
SO
4
0.5 mol/L
14.3 mL
200 mg N 20 % N 1 g
H
2
SO
4
1 mol/L
7.1 mL
Table 3-6: Titration solution 2
P-content P-factor N-content Sample size Titrant Titrant concentration Titrant volume
1 % P 6.25 0.16 % N 2 g
H
2
SO
4
0.01 mol/L
11.42 mL
2 % P 6.25 0.32 % N 1 g
H
2
SO
4
0.01 mol/L
11.42 mL
5 % P 6.25 0.80 % N 2 g
H
2
SO
4
0.1 mol/L
5.71 mL
10 % P 6.25 1.6 % N 2 g
H
2
SO
4
0.1 mol/L
11.42 mL
10 % P 6.25 1.6 % N 2 g
H
2
SO
4
0.25 mol/L
4.57 mL
20 % P 6.25 3.2 % N 2 g
H
2
SO
4
0.25 mol/L
9.14 mL
50 % P 6.25 8.0 % N 2 g
H
2
SO
4
0.5 mol/L
11.42 mL
General recommendation
Hydrochloric acid has the disadvantage of degassing. Therefore BUCHI recommends to use sulfuric
acid as titrant.
The correction factor for self prepared solutions is called a titer.
The use of standardized titration solutions make a titer determination unnecessary.
Exact titrant concentration = concentration x titer
The titer of the titrant must be known. In case, it is unknown, it must be determined.
Example:
Exact titrant concentration = 0.100 mol/L x 0.998
3 .4 Reference substances
Table 3-7: Reference substances
Name Purity % N theoretical
(100 % purity)
Recommended
sample size
Recommended titrant
concentration
Digestion necessary
Ammonium
dihydrogen
phosphate 99.5 12.18 0.8 g c(H
2
SO
4
) = 0.25
mol/L
No
Glycine 99.7 18.66 0.5 g c(H
2
SO
4
) = 0.25
mol/L
Yes
Phenylalanine 99.0 8.47 0.9 g c(H
2
SO
4
) = 0.25
mol/L
Yes
Ammonium
sulfate 99.5 21.21 0.4 g c(H
2
SO
4
) = 0.25
mol/L
No