Calcium determination:
Outlines of the method:The liquid samples are titrated against EDTA solution using Murexide indicator. This chemical analysis is suitable for the range of 0 to 250mg/l of calcium content.
Reagents:
1. sodium hydroxide solution – 4N
2. Murexide indicator solution – mix 0.20 g of Murexide and 100g of sodium chloride and grind to a fine powder.
3. Std EDTA solution (0.02N) – 3.72g of disodium ethylenediamine tetra amine dihydrate is dissolved in 1-litre solution distilled water solution. One millilitre of this solution is equal to 1mg of CaCO3
4. Std HCl – 0.02N
5. Triethanolamine – 20 percent (v/v)
Producer: Measure 100ml of the sample into a porcelain basin; neutralize it by adding Std HCl acid in a quantity equivalent to the alkalinity to methyl orange. Add 1ml of Std NaOH solution and allow to stand for 5min. Add 5ml of triethanolamine and about 50mg of Murexide indicator and titrate the solution with Std EDTA solution until the colour changes from pink to purple.
Calculation
Calcium (as CaCO3), mg/l = 1000 V1/V2
Where
V1 = volume in ml of EDTA sol required for titration
V2 = volume of sample in ml