PRINCIPLE:
The
method is applicable to the analysis of raw and drinking water and can be used
for water having magnesium content upto 5 mg/L. For sample containing higher
concentration smaller volume of the sample must be taken for the analysis.
Limit of Detection: 0.1 mg/L
REAGENTS
- Hydrochloric acid – 1 N and 0.1 N
- Lanthanum Chloride: 20 g/l of
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.
- Cesium Chloride: 20 g/l of Cs.
Dissolve 25 g of
cesium chloride in 1 Lit of 0.1 N HCl.
- Magnesium Stock Solution : Merck 1000 mg/L NIST Certified Reference Material of Dry a portion of magnesium oxide (MgO) at 180°C for 1 hour. Weigh 1.66 ± 0.01 g and dissolve in 1 N hydrochloric acid. Dilute with the same acid to 1000 ml in a volumetric flask. Store the solution in a polyethylene bottle.
PROCEDURE
Preparation
of test 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 if 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 0.1, 0.2, 0.3, 0.4 and 0.5 mg/L of Magnesium
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
magnesium directly.
REFERENCE: IS 3025 (Part 46): 1994
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