Hach DR/700 Procedures Manual page 305

PLATINUM,
SAMPLING AND STORAGE
Several locations within the bath should be sampled and combined to
obtain a representative sample of bath solution. Store the samples in
clean plastic or glass bottles. Analyze as soon as possible after
collection.
INTERFERENCES
Palladium and copper will react under the conditions of the procedure.
SUMMARY OF METHOD
The platinum in an electrolytic bath sample is first oxidized to Pt
Chromium 1 Reagent. The excess oxidant is then destroyed and the
platinum is reduced to the +2 oxidation state. Platinum ion then reacts
with N,N'-Diethyldithioooxamide Indicator to form an orange complex
which is proportional to the amount of platinum present.
CALIBRATION
A user calibration is required before bath sample can be analyzed. This
calibration is based on a 1:1000 dilution factor being used on the bath
solution.
Prepare an equivalent 10-g/L standard solution by pipetting 10.00 mL of
Platinum Standard solution into a 1-L volumetric flask. Dilute to the
line with demineralized water. Stopper. Invert at least 10 times to mix.
Refer to paragraph 2.2.4.1, Calibration Using Two Prepared Standards, in
the DR/700 instrument manual. Follow the platinum procedure starting at
Step 2 to develop the S1 and S2 standards. Use 15 mL of demineralized
water in Step 3. This is Standard 1 (S1) and is equal to 0.0 g/L Pt. Use 15
mL of the prepared platinum solution above in Step 2. This is Standard 2
(S2) and is equivalent to 10.0 g/L Pt.
REQUIRED REAGENTS
Description
Chromium 1 Reagent
Powder Pillows. . . . . . . . . . 2 . . . . . . . . . 100/pkg . . . . . . . . 2043-99
Hydrochloric Acid, ACS . . . . . 20 mL . . . . . 2.8 kg. . . . . . . . . . . 134-06
N,N'-Dimethyldithiooxamide
Indicator Solution . . . . . . . . 2 mL . . . . . . 100 mL . . . . . . . 23087-32
continued
Quantity
Per Test
50-55
Unit
4+
with
Cat. No.