Hach DR/700 Procedures Manual page 549

SILVER,
continued
STATISTICAL EVALUATION
A single operator repetitively tested samples of two laboratory prepared
solutions, using one DR/700, matched sample cells and two
representative lots of testing reagents. Testing 0.500 mg/L Ag
concentration samples the standard deviation was ±0.0036 mg/L Ag.
Testing zero concentration samples, the limit of detection was
0.0049 mg/L Ag. The limit of detection was calculated as three times
the standard deviation when testing zero concentration samples
(Adapted from Analytical Chemistry, 1980, 52, 2242-2249).
INTERFERENCES
Interfering studies were conducted by preparing a known silver solution
(about 0.4 mg/L) and the potential interfering ion. The ion was said to
interfere when the resulting concentration changed by ±10%.
Negative Interference:
Aluminum
Ammonia
Cadmium
Chloride
Chromium, hexavalent
Copper
Iron
Lead
Manganese
Nickel
Zinc
Positive Interference:
Calcium
Magnesium
Mercury
DIGESTION
The following digestion steps are for samples containing organic matter,
thiosulfate or cyanide from wastewater, silver electroplating baths and
silver strike solutions. Digestion must be carried out in a Digesdahl
Digestion Apparatus.
Interference Level
30 mg/L
750 mg/L
15 mg/L
19 mg/L
90 mg/L
7 mg/L
30 mg/L
13 mg/L
19 mg/L
19 mg/L
70 mg/L
600 mg/L
2000 mg/L
2 mg/L
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