221
mL graduated mixing cylinder. Dilute to the mark with deionized
water and mix thoroughly. Analyze 20 mL of this solution
according to the procedure.
Method Performance
Precision
In a single laboratory using standard solutions of 2.00 mg/L Mo
6+
and two representative lots of reagent with the instrument, a
single operator obtained a standard deviation of ±0.009 mg/L
Mo
6+
.
Estimated Detection Limit
The estimated detection limit for program 47 is 0.07 mg/L Mo
6+
.
For more information on the estimated detection limit, see
Section 1.
Interferences
Interference studies were conducted by preparing a molybdenum
standard solution (2 mg/L Mo
6+
) as well as a solution of the
potential interfering ion. When the standard solution
concentration changed by ±5% with a given ion concentration,
the ion was considered an interference.
Table 1 Negative Interferences
Ion Level above which it interferes (mg/L)
Iron 200
Copper 98
Chromium (Cr
6+
)4.5
1
Chloride 1,400
AMP (Phosphonate) 15
Phosphonohydroxyacetic Acid 32
Bisulfate 3,300
Nitrite 350
Aluminum 2
Acrylates 790
Alum 7
Lignin Sulfonate 105
Orthophosphate 4,500
Bicarbonate 5,650
EDTA 1,500
Borate 5,250
Ethylene Glycol 2% (by volume)
Sulfite 6,500
Diethanoldithiocarbamate 32
MOLYBDENUM, MOLYBDATE, LR, continued
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