Basic HTML Version
Appendix B
5/20/2009
15
computer memory, or use the automatic enter mode. The instrument is now ready
for running samples. Standards should be analyzed as unknowns during each run to
verify the K-factors and blank values.
11. PROCEDURE
11.1.
Aqueous Sample Preparation
11.1.1. Water Sample Filtration
Precombust 25-mm GF/F glass fiber filters at 500°C for 1.5 hours. Store filters
covered, if not immediately used. Place a precombusted filter on a fritted filter
base of the filtration apparatus and attach the filtration tower. Thoroughly shake
the sample container to suspend the particulate matter. Measure and record the
required sample volume using a graduated cylinder. Pour the measured sample
into the filtration tower. Filter the sample using a vacuum no greater than 10 in.
of Hg. Vacuum levels greater than 10 in. of Hg can cause filter rupture. Do not
rinse the filter following filtration. It has been demonstrated that sample loss
occurs when the filter is rinsed with an isotonic solution or the filtrate. Air dry
the filter after the sample has passed through by continuing the vacuum for 30
sec. Using flat-tipped forceps, fold the filters in half while still on the fritted
glass base of the filter apparatus. Store filters as described in Section 8.1.
11.1.2.
If the sample has been stored frozen in foil pouches, place in a drying oven at
47
o
C ± 2°C for 24 hours before analysis. Slightly open the pouch to allow drying.
When ready to analyze, fold, and insert the filter into a precombusted nickel
sleeve using forceps. Tap the filter pad down into the nickel sleeve using a
stainless steel rod. The sample is ready for analysis.
11.2.
Sample Analysis
11.2.1. As the filters are packed into the nickel sleeves they are placed into the 64
position sample wheel. The calibration series must be placed at the beginning of
the batch. The sample schedule consists of a conditioner, a blank, a conditioner
and three standards. ACS grade acetanilide must be used to calibrate the
instrument.
11.2.2. Set up the sample tray in the following manner (used for aqueous samples):
Position
#
Contents
Notes
Schedule
Entry
Weight
1
Capsule + sleeve
Blank
Blank
0
2
Conditioner
Acetanilide
(1500-2500 µg)
Conditioner
Weight of
Acetanilide
3
Capsule + sleeve
Blank
Blank
0
4
Conditioner
Acetanilide
(1500-2500 µg)
Conditioner
Weight of
Acetanilide
5
Standard
Acetanilide
(1500-2500 µg)
STD1
a
Weight of
Acetanilide
6
Standard
Acetanilide
(1500-2500 µg)
STD1
Weight of
Acetanilide
7
Standard
Acetanilide
(1500-2500 µg)
STD1
Weight of
Acetanilide
8
Sleeve + filter pad
Filter Blank
LRB
0
9-31
Samples
Volume