Hach DR2400 - Page 357

Lead
Lead
Lead_None_Other_LTK_Eng_Ody.fm Page 5 of 8
Sampling for Lead Contamination in Household Pipes for Point-of-use
Drinking Water
• The sample should be collected after sitting in pipes with no flow for 8 to 18
hours.
• Add 10 mL of pPb-1 Acid Preservative (Cat. No. 23685-31) to a one-liter
bottle.
• Turn on tap and collect exactly the first liter of water in the bottle containing
acid preservative.
• Cap and invert several times to mix.
• After two minutes the sample is ready for analysis. Steps 3 and 4 are skipped
in the analysis procedure. Use 100 mL of this preserved sample directly in
step 5.
Sampling for Lead Contamination from Drinking Water Sources Such as Well
Water or Water from Main Supply Lines
• Add 10 mL of pPb-1 Acid Preservative (Cat. No. 23685-31) to a one-liter
bottle.
• Turn on the tap for 3–5 minutes or until the water temperature has been
stable for 3 minutes.
• Collect exactly one liter of water into the bottle containing the acid
preservative.
• Cap and invert several times to mix.
• After two minutes the sample is ready for analysis. Steps 3 and 4 are skipped
in the analysis procedure. Use 100 mL of this preserved sample directly in
step 5.
• At least one liter should be collected to obtain a representative sample. If less
than one liter is collected, use 1 mL of pPb-1 Acid Preservative per 100 mL of
sample.
• If nitric acid is to be substituted for pPb-1 as a preservative or the sample is
digested, the buffering capacity of the pPb-2 Fixer Solution
(Cat. No. 23686-55) may be exceeded. Adjust the sample pH to 6.7–7.1 pH
with 5 N Sodium Hydroxide (Cat. No. 2450-53) after step 6.
Reagent Blank Adjustment
The LeadTrak
®
program will allow a reagent blank value from -5 to +5 µg/L Pb
to be automatically subtracted from the test result. When using the reagent
blank adjustment feature, the concentration value displayed after zeroing should
be 0 µg/L.
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.