Reagent preparation
C A U T I O N
Chemical exposure hazard. Obey laboratory safety procedures and wear all of the
personal protective equipment appropriate to the chemicals that are handled. Refer to the
current safety data sheets (MSDS/SDS) for safety protocols.
Prepare the arsenic absorber solution as follows:
1.
Weigh 1.00 g of silver diethyldithiocarbamate on an analytical balance.
2.
Add the powder to a 200-mL volumetric flask. Dilute to the mark with pyridine.
3.
Mix well to dissolve. Keep the reagent, tightly sealed, for a maximum of 1 month in an
amber bottle.
Calibration
This method requires a user-prepared calibration curve. Enter the calibration curve into
the instrument as a user program. Make a new calibration curve when a new lot of
reagents is used.
Prepare the standard solutions
Prepare the standard solutions for calibration as follows.
Items to collect:
•
1000-mg/L Arsenic Standard Solution
•
1000-mL volumetric flask
•
500-mL volumetric flasks (3), Class A
•
1–10 mL TenSette pipet and tips
•
Deionized water
1.
Prepare a 10.0-mg/L Arsenic Standard Solution as follows:
a.
Use a pipet to add 10.0 mL of the 1000-mg/L Arsenic Standard Solution into a
1000-mL volumetric flask.
b.
Dilute to the mark with deionized water.
2.
Prepare three calibration standard solutions (0.02, 0.04 and 0.20 mg/L arsenic) as
follows:
a.
Use a pipet to add 1.0 , 2.0 and 10.0 mL of the 10.0-mg/L Arsenic Standard
Solution into three different 500-mL volumetric flasks. Use Class A glassware.
b.
Dilute each flask to the mark with deionized water. Mix well.
Enter the calibration as a user program
After the calibration standards are prepared, make a user program to store the calibration
information in the instrument. Select the user program to measure the concentration of
samples. The steps that follow are general instructions for all instruments. Refer to the
user manual for the instrument that is used for the correct menu options.
1.
Use the test procedure to prepare the standard solutions for measurement. Make
sure to distill the standard solutions as shown in the test procedure.
2.
Go to
User Programs
.
3.
For the initial calibration, make a new user program. Set up the basic information for
the new program:
Option
Description
Program number
Enter an available number for the user program.
Arsenic Silver Diethyldithiocarbamate Method (0.200 mg/L)
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