 |
|||
|
Page Title:
Colorimetric method for fluorine |
|
||
| ||||||||||
|
|  MIL-L- 24131C(SH)
NOTE: Line interferences of first and higher order are rare. If a particular interference is suspected,
other lines of the interfering element should be sought, and if found, the chlorine or sulfur count rate
corrected for the contribution of the interfering lines.
4.3.4.3.5 Turbidimetric method for sulfur. Turbidimetric method for sulfur shall be as follows:
(a)
Solutions shall be prepared by fusing one gram samples of solid with 10 grams of sodium
carbonate at 1620F for two hours in a platinum crucible. The melt shall be dissolved in about
25 ml of water. Approximately 16 ml of concentrated hydrochloric acid (HCl, Sp. gr. = 1.19)
shall be added to the solution, and the solution shall be filtered. The volume of the filtrate
shall be adjusted to 50 ml with water and the temperature of the solution shall be adjusted to
between 60 and 85F.
(b)
From this point follow ASTM D516, Non-Referee Method A (turbidimetric method), for
sulfate in industrial water, with the following modifications:
(1)
To each of the standards prepared in accordance with the calibration method of ASTM
D516, add 10.8 grams of sodium chloride.
(2)
Read absorbance versus time and use the maximum absorbance reading. For the
concentration normally found in colloidal graphite in isopropanol, attainment of
maximum absorbance will require more than five minutes.
(c)
Calculate ppm sulfur by multiplying ppm sulfate by 0.3337.
4.3.4.3.6 Colorimetric method for fluorine. The sample shall be fused with sodium carbonate and
dissolved in water. The fluoride shall be distilled as hydrofluosilicic acid and shall be determined
colorimetrically, using the zirconium-alizarin visual method. Equally accurate alternate test methods,
approved in writing, may also be used.
(a)
Apparatus. A distillation assembly similar to that described in ASTM D1179. A burner can
be used if a quartz heating mantle is not available.
(b)
Reagents.
(1)
Acid-zirconyl-alizarin reagent. This is a mixture of two solutions:
Solution A - Dilute 101 ml of concentrated HCl to approximately 400 ml with water.
Add carefully 33.3 ml of concentrated H2SO4 to approximately 300 ml of water. After
cooling, mix the two acids.
Solution B - Dissolve 0.30g of zirconyl chloride octahydrate (ZrOCl2 8H2O) in
approximately 50 ml of water in a 1 liter volumetric flask. In a separate container,
dissolve 0.07g of sodium alizarin sulfonate (alizarin red S) in approximately 50 ml of
9
|
|
Privacy Statement - Press Release - Copyright Information. - Contact Us |
Click
here for thousands of PDF manuals