Limit Test for Aluminium

Title: Limit Test for Aluminium 

 

1. Objective: The limit test for Aluminium is provided to demonstrate that the content of aluminium does not exceed the limit given in the individual monograph in terms of ppm, i.e., the parts of aluminum of the substance being examined.

 

2. Principle: Limit test of Aluminium is based on the intensity of the fluorescence of the test solution, standard solution and the blank using an excitant beam and a secondary filter with a transmission band or a monochromator set to transmit at this wavelength.

 

3. Procedure:

• Preparation of Standard Solutions:

Note: All solutions should be prepared in Distilled/Purified Water.

• Aluminium Potassium Sulphate (0.176% w/v): Dissolve 0.176 g of Aluminium Potassium Sulphate in water and dilute to 100 ml with water.
• Aluminium Standard Solution (2 ppm Al): Dilute 2 volumes of Aluminium Potassium Sulphate (0.176% w/v) in 0.1M Sulphuric acid to 100 volumes with water immediately before use.
• Aluminium Standard Solution (10 ppm Al): Dilute 1 volume of a 1.39% w/v solution of Aluminium Nitrate to 100 volumes with
• Hydroxyquinoline Solution (5% w/v): Dissolve 0.5 g of Hydroxyquinoline in Chloroform and dilute up to 100 ml with Chloroform.
• 1M Sulphuric acid: Add 5.4 ml of Sulphuric acid carefully with equal volume of water, cool and dilute to 1000 ml with water.
• 1M Sulphuric acid: Add 54 ml of Sulphuric acid carefully with equal volume of water, cool and dilute to 1000 ml with water.

 

• Method:

Place the test solution in a separating funnel and shake with 2 quantities, each of 20 ml, and then with one 10 ml quantity of 0.5% w/v solution of Hydroxyquinoline in Chloroform. Dilute the combined Chloroform solutions to 50.0 ml with Chloroform (Test Solution).

Prepare a standard in the same manner using the prescribed reference solution.

Prepare a blank in the same manner using the prescribed blank solution.

Measure the intensity of the fluorescence of the test solution (f₁), of the standard (f₂) and of the blank (f₃) using an excitant beam at 392 nm and a secondary filter with a transmission band centered on 518 nm or a monochromator set to transmit at this wavelength.

The fluorescence of the test solution: (f₁– f₃).

The fluorescence of the standard solution: (f₂– f₃).  

Limit: The fluorescence of the test solution is not greater than that of the standard solution.

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