Hach DR2400 Manual page 478

Nitrogen, Ammonia
Accuracy Check
Nitrogen, Ammonia
Page 4 of 6
Standard Additions Method (Sample Spike)
1. After reading test results, leave the sample cell (unspiked sample) in the
instrument.
2. Touch . Touch
Options
additions procedure will appear.
3. Touch to accept the default values for standard concentration, sample
OK
volume, and spike volumes. Touch
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 a Nitrogen, Ammonia PourRite
150-mg/L NH –N (Cat. No. 21284-20).
3
5. Prepare three sample spikes. Fill three mixing cylinders (Cat. No. 1896-40)
with 25 mL of sample. Use the TenSette
of standard, respectively, to each sample and mix each thoroughly.
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
. Each addition should reflect approximately 100% recovery.
Read
7. After completing the sequence, touch
the standard additions data points, accounting for matrix interferences. Touch
, then select
View: Fit
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. To check accuracy, use the 10-mg/L Nitrogen, Ammonia Standard Solution
or a 50-mg/L Nitrogen, Ammonia Voluette
Alternatively, prepare a 40.0-mg/L ammonia nitrogen standard solution by
pipetting 20.00 mL of 100-mg/L Ammonia Nitrogen standard into a 50-mL,
Class A volumetric flask. Dilute to the mark with deionized water.
2. To adjust the calibration curve using the reading obtained with the
40.0 mg/L nitrogen ammonia standard solution, touch
program menu. Touch
3. Touch . Touch
On Adjust
concentration is used, touch the number in the box to enter the actual
concentration, then touch
See Section 3.2.4 Adjusting the Standard Curve on page 40 for more information.
. A summary of the standard
Standard Additions
to change these values. After values
Edit
®
Pipet to add 0.2, 0.4 mL and 0.6 mL
Graph
and touch
Ideal Line OK
®
.
Standard Adjust
to accept the displayed concentration. If an alternate
. Touch .
OK Adjust
®
Ampule Standard,
to view the best-fit line through
to view the relationship between
Ampule Standard.
on the current
Options
NitrogenAmm_TNT_High_SAL_Eng_Ody.fm