Hach BioTector B3500C, User Manual

Page: 71 / 165

Page 71
The calculation of the quantities required to prepare Potassium Hydrogen Phthalate (KHP) standard solutions
with various purities are given as an example below:
Name: Potassium Hydrogen Phthalate
Formula: C
8
H
5
KO
4
Carbon, 12 x8 = 96
Oxygen, 16 x4 = 64
Potassium, 39 x 1 = 39
Hydrogen, 1 x5 = 5____________
Total weight = 204.22 g/mol
47% of KHP is Carbon. Purity of the KHP is 99.9%. Therefore, to prepare a 1000 mgC/l standard solution,
add 2.13g of KHP in a flask and add enough deionized water to make it exactly 1 liter solution.
Note that the quantities required change with the % purity of the chemical used. Table 8 below gives the KHP
quantities required at various % purity for the preparation of 1000mgC/l calibration standard.
Table 8 Quantity of KHP required to prepare 1000 mgC/l standard at various purities.
% Purity of KHP
Quantity of KHP (grams)
to prepare 1000 mgC/l Standard
100 2.127
99.9 2.129
99.5 2.138
99.0 2.149
95.0 2.239
90.0 2.364
To prepare standard solutions containing more than 1000 mgC/l, the required solvent can be mixed directly
with deionized water. Table 9 below gives the required quantity of KHP for various concentration standard
solutions to be mixed with deionized water and added enough deionized water to make the solution exactly 1
liter.
Table 9 Quantity of KHP required to prepare various concentration TOC standard solutions.
TOC Standard Solution
Concentration (mgC/l)
Quantity of 99.9% KHP (grams)
to be added into 1 Liter DIW
1000 2.129
1250 2.661
1500 3.194
2000 4.258
5000 10.645
10000 21.290