rial) for each analyte obtained from the U.S.
Note: NG is a liquid and should not be dried.
Army Environmental Center, Aberdeen
Proving Ground, Maryland. (Calibration
10.1.2
standards are commercially available from
Place about 0.100 g (weighed to 0.0001 g) of a
several sources including Supelco, Accu
single analyte into a 100-mL flask and fill to vol-
Standard, Radian.)
ume with acetonitrile. The NG SARM is a solu-
tion of NG in acetone, which should be diluted
with acetonitrile.
8.0 SAMPLE COLLECTION, HANDLING,
AND PRESERVATION
10.1.3
Invert the flask several times until the analyte
8.1 Sample collection
Follow conventional sampling and sample
is dissolved. Store this stock solution in a refriger-
ator at 4C in the dark. Stock solutions may be
handling procedures as specified for semivolatile
organics in SW-846, Chapter 4.
used for up to one year.
10.1.4
8.2 Preservation and holding times
Water samples must be stored in the dark at
Calculate the concentration of the stock solu-
4C. Acetonitrile extracts should be stored in the
tion from the actual weight used (nominal con-
freezer. Holding times are the same as for semi-
centration = 1000 mg/L).
volatile organics.
10.2 Preparation of intermediate
standards solutions
9.0 QUALITY CONTROL
Refer to SW-846, Chapter 1, for specific quality
10.2.1
control procedures.
Prepare two intermediate standard solutions
by combining appropriate volumes of the various
stock solutions. The ECD response is dependent
9.1 Sample extraction validation
Refer to Method 3500.
on the number of nitro groups. Response is great-
est for TNT and least for the nitrotoluenes. One
(A) intermediate stock solution should contain
9.2 GC system validation
Refer to SW-846, Method 8000, Section 8.
DNB, 2,6-DNT, 2,4-DNT, TNB, TNT, RDX, 4-Am-
DNT, 2-Am-DNT, tetryl, and HMX at 1000 g/L;
the second (B) solution should contain NB, o-NT,
9.3 Predetermination of interferences
m-NT, p-NT, NG, and PETN at 5000 g/L and
Prior to preparation of stock solutions, the ace-
DNA at 1000 g/L. These solutions should be
tonitrile should be analyzed to determine possi-
stored in a freezer.
ble interferences with analyte peaks. If the aceto-
nitrile shows any contamination, a different batch
10.2.2
or lot should be used.
Prepare working standard solutions covering
the range of interest. Suggested ranges are within
10.0 CALIBRATION AND
0.5 to 500 g/L for one (A) set, and 2.5 to 2500 g/
STANDARDIZATION
L for the other (B) set; prepare by diluting the two
concentrated intermediate stock solutions with
10.1 Preparation of stock standards solutions
acetonitrile. These solutions should be stored in a
10.1.1
freezer, and may be used for 30 days. At a mini-
Dry about 0.15 g of each solid analyte standard
mum, a five-point calibration curve is generated.
(SARM) to a constant weight in a vacuum desic-
cator in the dark.
Note: The analytes TNB, TNT, and tetryl are un-
stable at low concentrations in some brands of
Note: The HMX, RDX, tetryl, PETN, and 2,4,6-
acetonitrile. If the response for these analytes de-
TNT are explosives and the neat material should
clines with time, another brand of acetonitrile
be handled carefully. HMX, RDX, and tetryl refer-
should be used. All standards should be kept re-
ence materials are shipped under water. Drying
frigerated at all times.
at ambient temperature requires several days. Do
NOT dry at heated temperatures.
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