MIL-DTL-10958G
1. Scope:
This method is applicable to the determination of calcium EDTA (the calcium chelate of the
disodium salt of ethylenediamine tetraacetic acid) in a variety of food products.
2. Principle:
The sample is clarified by filtering after treating with barium carbonate and filter aid. The
filtrate is treated with magnesium to remove interferences. Calcium EDTA is then determined in
a filtered portion of the sample. In a strongly acidic solution, calcium EDTA reacts with
zirconium, chelating an amount of zirconium equivalent to the calcium EDTA present. The
excess zirconium is determined by its reaction with xylenol orange producing a red colored
complex. The decrease in absorbance at 535 millimicrons is proportional to the calcium EDTA
present.
3. Reagents:
(a)
Filter acid. Celite, J-M- analytical filter aid.
(b)
Barium carbonate. Reagent grade.
(c)
Hydrochloric acid, 5N. Dilute 417 ml of concentrated hydrochloric acid to one liter.
(d)
Magnesium chloride solution. Dissolve 200 grams of reagent grade magnesium chloride
(MgCl2.6H2O) in 800 ml of distilled water.
(e)
Ammonium hydroxide, concentrated reagent.
(f)
Phosphoric acid, dilute. Dilute 10 ml of 85% reagent phosphoric acid to one liter.
(g)
Hydroxylamine hydrochloride, approximately 10%. Dissolve 100 grams of
hydroxylamine hydrochloride in water and dilute to one liter.
(h)
Calcium EDTA standard solution A. Dissolve 1.101 grams of the calcium EDTA
di-hydrate in water and dilute to one liter. One ml is equivalent to one mg of calcium
EDTA.
Determination of calcium EDTA
Calcium EDTA standard solution B. Dilute 25.0 ml of solution A (3h) to volume in a 500-ml
volumetric flask.
Zirconyl chloride standard solution A. Dissolve 3.454 grams of zirconyl chloride octahydrate
(ZrOCL2.8H2O), in 100 ml of concentrated hydrochloric acid and dilute to one liter.
Standardize the solution by the hydroxide procedure. One ml is approximately equivalent to one
mg of zirconium.
Zirconium standard solution B. Dilute a volume of the zirconium standard A equal to 6 mg of
zirconium and 20 ml of concentrated hydrochloric acid to one liter. Prepare fresh daily.
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