Hach DR2400 - Page 340

Iron, Total
Iron, Total
Page 4 of 6
IronTot_AVPP_Other_FVR_Eng_Ody.fm
Sample Collection, Storage and Preservation
Collect samples in acid-cleaned glass or plastic containers. No acid addition is
necessary if analyzing the sample immediately. To preserve samples, adjust the
pH to 2 or less with concentrated nitric acid (about 2 mL per liter)
(Cat. No. 152-49). Preserved samples may be stored up to six months at room
temperature. Before analysis, adjust the pH to between 3 and 5 with 5.0 N
Sodium Hydroxide Standard Solution (Cat. No. 2450-32). Correct the test result
for volume additions; see Section 3.1.3 Correcting for Volume Additions on page 29.
If only dissolved iron is to be determined, filter the sample before acid addition.
Accuracy Check
Standard Additions Method (Sample Spike)
1. After reading test results, leave the sample cell (unspiked sample) in the
instrument.
2. Touch
Options. Touch Standard Additions. A summary of the standard
additions procedure will appear.
3. Touch
OK to accept the default values for standard concentration, sample
volume, and spike volumes. Touch
Edit to change these values. After values
are accepted, the unspiked sample reading will appear in the top row.
See Standard Additions in the instrument manual for more information.
4. Snap the neck off an Iron Voluette Ampule Standard, 50-mg/L.
5. Prepare a 0.1 mL sample spike by adding 0.1 mL of standard to the unspiked
sample. Touch the timer icon. After the timer beeps, read the result.
6. Prepare a 0.2 mL sample spike by adding 0.1 mL of standard to the 0.1 mL
sample spike. Touch the timer icon. After the timer beeps, read the result.
7. Prepare a 0.3 mL sample spike by adding 0.1 mL of standard to the 0.2 mL
sample spike. Touch the timer icon. After the timer beeps, read the result.
Each addition should reflect approximately 100% recovery.
Note: For AccuVac Ampuls, fill three mixing cylinders (Cat. No. 1896-41) with 50-mL of sample and
spike with 0.2 mL, 0.4 mL, and 0.6 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.
8. 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
1. Prepare a 1.00-mg/L Fe standard solution by pipetting 1.00 mL of Iron
Standard Solution, 100-mg/L, into a 100-mL volumetric flask. Dilute to the
mark with deionized water. Stopper and invert to mix. Prepare this solution
daily. Perform the iron procedure as described above.
2. To adjust the calibration curve using the reading obtained with the
1.00 mg/L Standard Solution, touch
Options on the current program menu.
Touch
Standard Adjust.