Hach DR/700 Procedures Manual page 503

NICKEL,
continued
3+
Cr
6+
Cr
2+
Cu
-
F
3+
Fe
2+ 2+
Fe and CO
+
K
2+
Mg
2+
Mn
6+
Mo
+
Na
2+
Pb
2+
Zn
Highly buffered samples or extreme sample pH may exceed the
buffering capacity of the reagents and required sample pretreatment; see
Interferences, pH (Section I).
Chelating agents, such as EDTA, interfere. Use either the Digesdahl or
vigorous digestion (Section I) to eliminate this interference.
SUMMARY OF METHOD
After buffering the sample and masking any Fe
the nickel is reacted with 1-(2-Pyridylazo)-2-Naphthol indicator. The
indicator forms complexes with most metals present. After color
development, EDTA is added to destroy all metal-PAN complexes
except nickel and cobalt. Cobalt must be absent from samples.
REQUIRED REAGENTS
Nickel Reagent Set (100 Tests*) . . . . . . . . . . . . . . . . . . . . . . . . 22426-00
Includes: (4) 7005-66, (4) 21501-66, (2) 21502-37
Description
EDTA Reagent
Powder Pillows. . . . . . . . . . 2 pillows . . . 50/pkg . . . . . . . . . 7005-66
Phthalate-Phosphate Reagent
Powder Pillows. . . . . . . . . . 2 pillows . . . 50/pkg . . . . . . . . 21501-66
20 mg/L
40 mg/L
15 mg/L
20 mg/L
10 mg/L
interferes directly and
must not be present.
500 mg/L
400 mg/L
25 mg/L
60 mg/L
5000 mg/L
20 mg/L
30 mg/L
Quantity
Per Test Unit
55-55
3+
with pyrophosphate,
Cat. No.
Cat. No.