SOP for STANDARD WORKING PROCEDURE FOR ESTIMATION OF CALCIUM

PRINCIPLE:

            This method is applicable to the analysis of raw and drinking water and can be used for water having Calcium content up to 5 mg/L. For sample containing higher concentration smaller volume of the sample must be taken for the analysis.

Limit of Detection: 1.0 mg/L

REAGENTS

1. Hydrochloric acid : 1 N and 0.1 N

2. Lanthanum Chloride: 20 g/l of La.

To a 1-liter volumetric flask add 24 g of lanthanum oxide (La₂O₃). Slowly and cautiously add 50 ml of concentrated hydrochloric acid. While stirring to dissolve the lanthanum oxide. Make up to the mark with water.

3. Cesium Chloride: 20 g/l of Cs.

Dissolve 25 g of cesium chloride in 1 Lit of 0.1 N HCl.

4. Calcium stock Solution: Dry Calcium Carbonate (CaCO₃) at 180°C for 1 hour and allow it to cool in a desiccator. Suspend 2.50 ± 0.01 gm of the dried material in 100 ml of water. Add slowly the minimum amount of 0.1 N HCl to dissolve the Calcium Carbonate. Boil briefly to expel dissolved carbon dioxide, cool and transfer the solution quantitatively to a 1000 ml volumetric flask and dilute to mark with 0.1 N HCl

PROCEDURE:

Preparation of Teat Solution: Sample containing particulate matter after acidification shall be filtered to prevent clogging of the nebulizer and burner systems. To a 100 ml volumetric flask, add 10 ml of lanthanum chloride solution of an air acetylene flame is to be used or 10 ml of cesium chloride solution if a nitrous oxide acetylene flame is to be used. Add 10 ml of the sample and make up to the mark with 0.1 N HCl.

Preparation of Blank Solution: Prepare a blank test simultaneously using the same reagents in the same quantities and following the same procedure, but replacing the volume of the test sample used as above by equal volume of distilled water.

Preparation of Standard Solution: Prepare a reagent blank and a series of 100 ml standards containing 1.0, 2.0, 3.0, 4.0 and 5.0 mg/L of Calcium by diluting a suitable volume of the standard solution with dilute HCl.

Analysis: Operate the instrument as per SOP. Aspirate the blank, series of standard and test sample solutions and read the concentration in mg/l of Calcium directly.

REFERENCE: IS 3025 (Part 40): 1991