Hach DR2400 - Page 397

Molybdenum, Molybdate
Molybdenum, Molybdate
Molybdenum_AVPP_High_MAA_Eng_Ody.fm Page 5 of 6
5. Prepare three sample spikes. Fill three Mixing Cylinders (Cat. No. 1896-40)
with 30 mL of sample. Use the TenSette
®
Pipet to add 0.2 mL, 0.4 mL, and
0.6 mL of standard, respectively, to each sample and mix thoroughly.
Note: For AccuVac Ampuls, fill three Mixing Cylinders (Cat. No. 1896-42) with 60-mL of sample
and spike with 0.4 mL, 0.8 mL, and 1.2 mL of standard. Transfer 40 mL from each of the
three mixing cylinders to three 50-mL Beakers (Cat. No. 500-41H). Analyze each standard
addition sample as described in the procedure above. Accept each standard additions
reading by touching Read. Each addition should reflect approximately 100% recovery.
6. Analyze each sample spike as described in the procedure above, starting with
the 0.2 mL sample spike. Accept each standard additions reading by touching
Read. Each addition should reflect approximately 100% recovery.
7. After completing the sequence, touch
Graph to view the best-fit line through
the standard additions data points, accounting for matrix interferences. Touch
View: Fit, then select Ideal Line and touch OK to view the relationship between
the sample spikes and the “Ideal Line” of 100% recovery.
See Section 3.2.2 Standard Additions on page 32 for more information.
Standard Solution Method
To assure the accuracy of the test, use a Molybdenum Standard Solution,
10.0-mg/L Mo
6+
. Follow the procedure for powder pillows or AccuVac Ampuls.
Standard Adjust
1. Use a Molybdenum Standard Solution, 10.0 mg/L Mo
6+
to perform the
molybdenum procedure as described above.
2. To adjust the calibration curve using the reading obtained with the
10.0-mg/L standard solution, touch
Options on the current program menu.
Touch
Standard Adjust.
3. Touch
On. Touch Adjust to accept the displayed concentration (the value
depends on the selected chemical form). If an alternate concentration is used,
touch the number in the box to enter the actual concentration, then touch
OK.
Touch
Adjust.
See Section 3.2.4 Adjusting the Standard Curve on page 40 for more information.
Method Performance
Precision
Standard: 10.0 mg/L Mo
6+
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.
Program 95% Confidence Limits of Distribution
320 9.9–10.1 mg/L
Mo
6+
322 9.8–10.2 mg/L Mo
6+
Program Portion of Curve ∆Abs ∆Concentration
320 Entire range 0.010 0.3 mg/L
Mo
6+
322 Entire range 0.010 0.1 mg/L Mo
6+