Arsenic
Arsenic
Page 4 of 6
Arsenic_None_Other_SDC_Eng_Ody.fm
Reagent Preparation
Prepare the arsenic absorber solution as follows:
1. Weigh 1.00 g of silver diethyldithiocarbamate on an analytical balance.
2. Transfer the powder to a 200-mL volumetric flask. Dilute to volume with
pyridine. You must use pyridine only in a fume hood and wear chemical
resistant gloves. Read the MSDS before using pyridine.
3. Mix well to dissolve. Store the reagent, tightly sealed, in an amber bottle. The
reagent is stable for one month if stored in this manner. Larger volumes of
reagent can be prepared if the reagent is used within one month.
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. Prepare a 100-mg/L arsenic working standard by pipetting 10.0 mL of
Arsenic Standard Solution, 1000-mg/L As (Cat. No. 14571-42) into a 100-mL
volumetric flask. Dilute to volume with deionized water.
5. Prepare three sample spikes. Fill three mixing cylinders (Cat. No. 1896-40)
with 250 mL of sample. Use the TenSette Pipet to add 0.1 mL, 0.2 mL, and
0.3 mL of standard, respectively, to each sample and mix thoroughly.
6. 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
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 check accuracy, use a 0.100 mg/L arsenic standard solution prepared as
follows:
1. Pipet 1 mL of a 1000-mg/L Arsenic Standard Solution into a 100-mL Class A
volumetric flask. Dilute to the mark with deionized water and mix
thoroughly.
2. Pipet 10 mL of the solution prepared in step a into a 1 L class A volumetric
flask. Dilute to the mark with deionized water and mix thoroughly. This is a
0.100-mg/L arsenic standard solution.
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