383
acid-washed 100-mL Class A volumetric flask. Dilute to the
mark with deionized water.
Method Performance
Precision
In a single laboratory, using a standard solution of 3.00 mg/L
PO
4
3-
and two lots of reagent with the instrument, a single
operator obtained a standard deviation of ±0.06 mg/L PO
4
3-
.
Estimated Detection Limit
The estimated detection limit for program 82 is 0.07 mg/L PO
4
3-
.
For more information on the estimated detection limit,
see Section 1.
Interferences
The following may interfere when present in concentrations
exceeding those listed below:
Store PhosVer 3 Reagent Powder Pillows in a cool,
dry environment.
Substance Interference Level and Treatment
Aluminum 200 mg/L
Arsenate Interferes at any level.
Chromium 100 mg/L
Copper 10 mg/L
Iron 100 mg/L
Nickel 300 mg/L
Silica 50 mg/L
Silicate 10 mg/L
Sulfide 90 mg/L
Turbidity (large amounts) May cause inconsistent results because the acid
present in the powder pillows may dissolve
some of the suspended particles and because of
variable desorption of orthophosphate from the
particles.
Zinc 80 mg/L
Highly buffered samples or
extreme sample pH
May exceed the buffering capacity of the
reagents and require sample pretreatment; see
pH
Interferences (Section 1).
PHOSPHORUS, TOTAL, continued
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