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Formaldehyde
Method Performance
Summary of Method
Formaldehyde
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 Formaldehyde Voluette
L CH
O.
2
®
5. Use a TenSette
Pipet to add 0.2 mL of the standard to a 100-mL volumetric
Class A flask. Dilute to volume with formaldehyde-free water and mix well.
Prepare daily. This is an 8000-µg/L (8-mg/L) formaldehyde standard.
6. Prepare three sample spikes. Fill three mixing cylinders (Cat. No. 1896-40)
with 25 mL of sample. Use the TenSette
0.3 mL of 8000-µg/L standard, respectively, to each sample and mix
thoroughly.
7. Analyze each sample spike as described in the procedure above, starting with
the 0.1 mL sample spike. Accept each standard additions reading by touching
. Each addition should reflect approximately 100% recovery.
Read
8. 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
Prepare a 320-µg/L Formaldehyde Standard Solution by pipetting 1.0 mL of the
8000-µg/L solution from the Accuracy Check into a 50-mL mixing cylinder. Dilute
to 25.0 mL with formaldehyde-free water. Run the test directly on this sample.
Precision
Standard: 300 µg/L CH
Program
200
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
Portion of Curve
Entire range
See Section 3.4.5 Sensitivity on page 44 for more information.
. A summary of the standard
Standard Additions
to change these values. After values
Edit
®
®
Pipet to add 0.1 mL, 0.2 mL, and
Graph
and touch
Ideal Line
OK
O
2
95% Confidence Limits of Distribution
285–315 µg/L CH
∆Abs
0.010
Ampule Standard, 4000-mg/
to view the best-fit line through
to view the relationship between
O
2
∆Concentration
3 µg/L CH
2
Formaldehyde_PP_Other_MBT_Eng_Ody.fm
O
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