1、Field
Analytical methods for the amine concentration

2、Abstract
Organic amine is a weak alkaline compounds, which reacts with hydrochloric acid to produce the amine hydrochloride. In this way a titration can be used for determination of amine concentration.

3、Materials
100 mL volumetric flask;
2 mL and 5 mL, 10 mL pipette;
150 mL conical flask;
25 mL burette acid type;
Support Hob.

4、Reagent
0.05 mol/L standard hydrochloric acid solution;
Mixed indicator: 1 g/L of methyl methyl red ethanol solution and 1 g/L times mixed in a ratio of 2:1 volume of ethanol solution.

5、Procedures
5.1 Transfer certain volume of sample V (typically 1- 3 mL) into 150 ml conical flask with pipette, then use distilled water make up to a volume between 50 to 60 mL. Samples quantity is determined by the amine concentration, small amount of sample for a high concentrations of amine, and vice versa. 

5.2 Add 4 drops of mixed indicator into the sample, mixed well, with a green colour, then titrated with 0.05 mol/L standard acid solution with an end point of change colour to a light purple, record consumed volume V1 of the standard acid solution.

5.3 If the sample of amine concentration is too high or the sample is a pure amine, Then a further dilution on the sample is required:

5.3.1 Transfer certain volume V (typically 1 - 3 mL) of sample with pipette into a 100 mL volumetric flask. Diluted it with distilled water to scale, mixed well.

5.3.2 Transfer V2 volume (generally 5 or 10 mL) of sample with a pipette and then diluted to 50 to 60 ml with distilled water in a 150 ml conical flask, The amount of sample taking is depended on the concentration of amine.

5.3.3 Add 4 drops of mixed indicator to, mixed well, with a green colour, titrated with standard acid solution (0.05 mol/L) until a light purple colour, record the consumed volume V1 of standard acid solution.

6、Notes
Analysis involves in acid and alkali. Needs to take care when handling them.

7、Calculation
7.1 Sample without dilution

                    
7.2 Sample with a dilution

              
A  -  grams per litre of amine sample, g/L.
C1 -  standard hydrochloric acid solution concentration, mol/L.
V1 -  consumed volume of standard acid solution, mL.
V  -  sample volume , mL.
V2 -  samples volume after dilution, mL.