Hach DR2400 - Page 730

Silver
Silver
Page 4 of 6
Silver_PP_Other_CLR_Eng_Ody.fm
Standard Solution Method
Prepare a 0.5 mg/L silver standard solution as follows:
1. Pipet 0.50 mL of Silver Standard Solution, 1000 mg/L, into a 1000-mL
volumetric flask using a Class A volumetric pipet. Dilute to the mark with
deionized water. Prepare this solution daily. Perform the silver procedure as
described above.
2. To adjust the calibration curve using the reading obtained with the 0.5-mg/L
silver standard solution, touch
Options on the current program menu. Touch
Standard Adjust.
3. Touch
On. Touch OK to accept the displayed concentration. If an alternate
concentration is used, touch the number in the
Adjust to field and enter the
actual concentration. Touch
OK.
See Section 3.2.4 Adjusting the Standard Curve on page 40 for more information.
Method Performance
Precision
Standard: 0.500 mg/L Ag
See Section 3.4.3 Precision on page 44 for more information, or if the standard
concentration did not fall within the specified range.
Sensitivity
See Section 3.4.5 Sensitivity on page 44 for more information.
Digestion
This digestion is for samples containing organic matter, thiosulfate or cyanide.
Possible sources for these compounds are wastewater, silver electroplating baths
and silver strike solutions. Digestion should be done with a Digesdahl Digestion
Apparatus.
Warning: Always
wear safety glasses
and use a safety
shield, or operate the
Digesdahl within a
closed fume hood.
Follow the additional
safety precautions in
the Digesdahl
Digestion Apparatus
Manual.
Caution: Poisonous hydrogen cyanide gas may be generated during this
digestion. Use a fume hood.
1. Add an appropriate size sample to the 100-mL digestion flask for use with
the Digesdahl. Add several boiling chips to prevent bumping.
Note: Appropriate sample size is determined experimentally. The final sample concentration (after
dilution to 100 mL) should be 0–0.6 mg/L. Larger dilutions may be necessary for
electroplating baths and silver strike solutions. Do not exceed the maximum sample volume
of 25 mL. Several 25-mL aliquots may be digested in succession to concentrate a very dilute
sample.
2. Turn on the water aspirator and make sure there is suction in the
fractionating head.
Program 95% Confidence Limits of Distribution
660 0.493–0.507 mg/L Ag
Portion of Curve ∆Abs ∆Concentration
Entire range 0.010 0.005 mg/L Ag