Nitriles | Karl Fischer titrator AQ-300/MOICO-A19 - JM Science
HIRANUMA APPLICATION DATA Karl Fischer Titrator Data No. KF7 Nov.28. 2018
Water contents Nitriles

1. Abstract

 Water content of Nitriles could be determined by Karl Fischer coulometric titrator. In coulometric titration, iodine of Karl Fischer reagent is generated by electrolysis and generated iodine quantitatively reacts with water. Reaction formula is described below.

 H₂O + I₂ + SO₂ + 3RN + CH₃OH → 2RN・HI + RN・HSO₄CH₃

 2RN・HI → I₂ + 2RN + 2H⁺ + 2e⁻

 Nitriles do not interfere the Karl Fischer reaction and direct injection method could apply. Anode solution is selected in accordance with sample solubility. General use of anode solution contain methanol as solvent. When the sample like a long chain hydrocarbon has poor solubility in methanol, anode solution containing chloroform or hexanol or toluene is used.

2. Apparatus and Reagents

(1) Apparatus    
  Titrator : HIRANUMA Karl Fischer Coulometric titrator AQ-series or MOICO-A19
  Electrolytic cell : Standard Cell
Fritless Cell (No cathode solution required)
(2) Reagents    
  Anode solution : HYDRANAL Coulomat AG (Honeywell)
  Cathode solution : HYDRANAL Coulomat CG (Honeywell)

3. Procedure

(1) Fill 100 mL of anode solution and one ampoule of cathode solution into the electrolytic cell as shown in Fig.3.1. When fritless cell is used, cathode solution is not necessary.
(2) Start blanking to attain stable background.
(3) Wash the syringe with sample.
(4) Draw the sample into syringe and then weigh the syringe.
(5) Inject sample from rubber septum of electrolytic cell as shown in Fig.3.2.
(6) Start titration. Measurement parameter is shown in Table 4.1.
(7) Weigh the syringe again and then set the difference of weight to sample size.

Fig.3.1. Preparation of the reagents. (Standard Cell)



Fig.3.2. Injection of sample.

4. Parameters and results

Table 4.1. Parameter.

Condition File    
Cal Mode 0:Sample weight(net)  
  X=(H₂O-BLANK)/SIZE  
Interval Time 20 sec
Current SLOW  
S-Timer 0 min
Blank Value 0 µg
Unit Mode AUTO  
Auto Interval 0 g
Minimum Count 5 µg
Back Ground ON  
Sample Size Input Every Time  
Cell Type Standard/Fritless  

 

Table 4.2. Results of water content measurement in nitriles.

Sample Cell Sample
Size (g)
Water
(μg)
Water Content
(ppm)
Statistics Results
Acetonitrile Standard 1.5175 151.1 99.6 Avg. 99.3 ppm
    1.5675 158.5 101.1 SD 2.0 ppm
    1.5602 151.5 97.1 RSD 2.0 %
             
  Fritless 1.5305 153.7 100.4 Avg. 99.8 ppm
    1.4616 147.1 100.6 SD 1.2 ppm
    1.5896 156.4 98.4 RSD 1.2 %
3-Ethoxypropionitrile Standard 0.78380 255.4 325.8 Avg. 325.9 ppm
    0.77352 253.0 327.1 SD 1.2 ppm
    0.97904 318.0 324.8 RSD 0.4 %
             
  Fritless 0.95859 312.6 326.1 Avg. 325.3 ppm
    0.87339 283.5 324.6 SD 0.8 ppm
    0.95782 311.6 325.3 RSD 0.2 %

5. Note

(1) Use dried syringe and syringe vial in Fig.5.1 for preventive of contamination by atmospheric water.
(2) To measure 100 µg or less water detection, make sure stability of blanking. Low and stable background value is important factor for trace level of water measurement.
(3) Select anode solution according to the solubility of the sample. For example, Hydranal coulomat AG-H and Hydranal coulomat Oil are suitable for long chain hydrocarbons and oil samples.
(4) The optimized electrolysis control for fritless cell of AQ series released after 2009 improves the measurement accuracy of fritless cell. It can be used with the evaporator as well. Suitable reagent for fritless cell is required. For example, Hydranal coulomat AG and AG-Oven are compatible with fritless cell.


FFig.5.1. Draw the sample from syringe vial.


Keywords: Karl Fischer, Coulometric titration, Direct injection, Nitrille, Fritless cell
Hiranuma aquacounter aq-300 coulometric karl fischer titratorHiranuma aquacounter coulometric karl fischer titrator moico-a19Water contents

Featured Instruments

Aquacounter Potentiometric Titrator COM-A19 | HiranumaAquacounter Potentiometric Titrator COM-A19 | Hiranuma
Hiranuma Aquacounter Potentiometric Titrator COM-A19 | Hiranuma
Sale price$11,490.00 USD Regular price$12,490.00 USD

Featured Titrators

View all
Aquacounter AQ-300 Coulometric Karl Fischer Titrator | Hiranuma
Hiranuma Aquacounter AQ-300 Coulometric Karl Fischer Titrator | Hiranuma
Sale price$5,500.00 USD Regular price$6,990.00 USD
Aquacounter Volumetric Karl Fischer Titrator MOIVO-A19 | Hiranuma
Hiranuma Aquacounter Volumetric Karl Fischer Titrator MOIVO-A19 | Hiranuma
Sale price$11,990.00 USD Regular price$13,990.00 USD
Aquacounter Coulometric Karl Fischer Titrator MOICO-A19 | Hiranuma
Hiranuma Aquacounter Coulometric Karl Fischer Titrator MOICO-A19 | Hiranuma
Sale price$10,990.00 USD Regular price$12,490.00 USD
Aquacounter Potentiometric Titrator COM-A19 | HiranumaAquacounter Potentiometric Titrator COM-A19 | Hiranuma
Hiranuma Aquacounter Potentiometric Titrator COM-A19 | Hiranuma
Sale price$11,490.00 USD Regular price$12,490.00 USD
Aquacounter AQV-300 Volumetric Karl Fischer Titrator | Hiranuma - JM Science
Hiranuma Aquacounter AQV-300 Volumetric Karl Fischer Titrator | Hiranuma
Sale price$5,500.00 USD Regular price$6,990.00 USD