MIL-DTL-46225D
about 30 mL water. Filter off any further precipitate and make the filtrate up to 50 mL. The
blank solution should also be reduced in volume similarly to 1 mL, then it should be transferred
to a 50 mL volumetric flask and the volume made up to 30 mL with cold water. 15 mL of the 10
ppm copper and iron standard shall be pipetted into the flask for the blank, and the flask filled to
volume with cold water, and mixed. The sample solution and the blank solution with added
standard shall be analyzed using either atomic absorption spectroscopy or Inductively Coupled
Plasma (ICP) spectroscopy. The quantities of copper and iron in the sample should be less than
that of the acid blank solution with added standards.
4.6.2.6 Chloride, nitrates and acetates. Divide the filtrate obtained in 4.6.2.3 into two
equal portions. Retain second portion for the acetate determination in 4.6.2.6.6. Pass hydrogen
sulfide through the first portion for a few minutes and allow the beaker to stand on a steam bath
to remove all the hydrogen sulfide and to coagulate the precipitate. Filter off the precipitate and
make the volume of the filtrate up to 50 mL. Divide filtrate into two equal 25 mL portions which
will be used for chloride and nitrate determination in 4.6.2.6.2 and 4.6.2.6.4.
4.6.2.6.1 Solution for chloride determination.
a. Nitric acid. 70 percent
b. Silver nitrate. 0.1N, dissolve 1.69 g of silver nitrate in 100 mL distilled water.
c. Standard chloride solution. Dissolve 0.085g of potassium chloride in 500 mL
distilled water.
4.6.2.6.2 Chloride procedure. Transfer first portion of filtrate obtained in 4.6.2.6 to a
Nessler tube. Add 1 mL concentrated nitric acid and 1 mL 0.1N silver nitrate solution. Compare
the turbidity with that of a standard, equivalent to 0.02 percent lead chloride, in a second Nessler
tube. Place 1 mL of the standard chloride solution in a Nessler tube, add 1 mL of 0.1N silver
nitrate and make up to 50 mL. The turbidity present in the chloride determination should be the
same or less than that of the standard.
4.6.2.6.3 Solution for nitrate determination.
a. Diphenylamine Solution. Dissolve 0.5 g of diphenylamine in 50 mL of 95-98%
sulfuric acid.
b. Standard nitrate solution. Dissolve 0.125 g lead nitrate in 500 mL of distilled
water.
4.6.2.6.4 Nitrate procedure. Transfer second portion of filtrate obtained in 4.6.2.6 to a
100 ml beaker and evaporate on a steam bath to about 2 mL. Transfer, quantitatively, to a test
tube, add 2 mL concentrated sulfuric acid and 1 drop diphenylamine solution. The color
obtained shall be equal or less than the color obtained with that of a standard (i.e., pipet 2 mL of
standard nitrate solution into a test tube, add 2 mL concentrated sulfuric acid and 1 drop of
diphenylamine solution).
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