minutes and sonicated overnight at 30C. The vi-
ges contained about 50% solids by weight and had
als were centrifuged and a 5-mL aliquot of each
become aerobic by the time of analysis. Sludge
basic extract of the Day-15 compost was removed
samples were air-dried overnight prior to analy-
sis. Subsamples weighing 2.00 g were added to
and diluted to 10 mL with concentrated H2SO4.
40-mL glass vials, which were sealed with Teflon-
The remaining 5 mL of basic extract was left in the
lined caps. A 10-mL aliquot of HPLC-grade aceto-
vial with the residue and 5 mL of concentrated
nitrile was added and the sample mixed on a vor-
H2SO4 was added. Acidified residues were soni-
cated for six hours at 30C, centrifuged, and 5-mL
tex mixer for one minute. The vials were placed in
an ultrasonic bath and sonicated overnight at 30C.
aliquots removed and neutralized with 1.2 M
After sonication, a 10-mL aliquot of aqueous cal-
Na2HPO4. As a precaution, 3,5-dinitroaniline (3,5-
cium chloride solution (5 g/L) was added to has-
DNA) was added as a surrogate to the neutral-
ten flocculation, the sample vortexed briefly, and
ized digests to monitor recovery from the Sep-Pak
centrifuged at 2000 g for five minutes. The aque-
cartridges.
ous CaCl2/acetonitrile extract was decanted, fil-
Acid hydrolysis of base-hydrolyzed residues
tered, and saved for HPLC analysis. The vials were
was modified to eliminate the spattering of diges-
refilled with fresh CaCl2/acetonitrile solution,
tion mixture when concentrated acid was added
vortexed, centrifuged, and decanted repeatedly
too quickly. A sample of Day-10 compost was
(usually three times was adequate) until no more
solvent-extracted, rinsed, and base-hydrolyzed as
above. A 5-mL aliquot of 15C 50% H2SO4 was
unbound explosives residues or free amino trans-
added to the 5 mL of base-hydrolysis mixture. The
formation products were detectable by HPLC. The
heat generated using this procedure did not cause
resulting solvent-extracted residues were decanted
spattering.
and air-dried overnight before hydrolysis experi-
ments were initiated.
Recoveries
Spike-recovery experiments were performed by
Acid hydrolysis
The first of two hydrolysis procedures was an
ucts dissolved in acetonitrile to field-moist com-
acid hydrolysis. An air-dried residue from the ac-
posts, digester sludge, and sand. The spiked con-
etonitrile extraction was transferred to a 22-mL
vial, 10 mL of 50% aqueous H2SO4 was added, the
centrations ranged from one to three mg/kg (dry
material) for one set of triplicate samples, and 25
sample vortexed for one minute, then placed into
an ultrasonic bath for six hours at 30C. Follow-
to 75 mg/kg for an additional unreplicated set.
The acetonitrile was evaporated in a few minutes
ing sonication, the vial was centrifuged at 2000 g
as the mixtures were homogenized. The air-dried
for five minutes and a 5-mL aliquot of the acid
samples were extracted with acetonitrile in accor-
digest removed and neutralized by adding 100 mL
dance with the procedure described earlier.
of aqueous, 1.2 M Na2HPO4 (pH 8.4). The result-
ing solution (pH 6.5) was pulled through a 6-mL
times produced a white, gelatinous precipitate. A
Sep-Pak PorapakRDX cartridge at 10 mL/minute
spike-recovery experiment was performed to de-
using vacuum. The cartridge was washed with an
termine the relationship between final pH and re-
additional 20 mL of reagent-grade water to remove
covery. Residues from solvent-extracted compost
salts, then evacuated for five minutes to remove
samples were spiked at 16 mg/kg with the ADNTs
residual water. A 5-mL aliquot of acetonitrile was
and the DANTs. The samples were immediately
added and allowed to drip through the cartridge
base/acid hydrolyzed. The hydrolysates were sub-
at 5 mL/minute. Reagent-grade water (5 mL)
divided and neutralized to pH 4.0, 5.0, or 6.0. The
washed through the cartridge into the acetonitrile
3,5-DNA surrogate was added and the neutralized
extract. The mixture was diluted to 10.0 mL using
hydrolysate passed through the solid-phase ex-
reagent-grade water and analyzed by HPLC.
traction cartridges.
To evaluate the recovery of the base/acid hy-
Base/acid hydrolysis
The second hydrolysis procedure combined a
drolysis procedure, 0.5 M NaOH was added to two
base and acid hydrolysis. Solvent-extracted and
solvent-extracted compost samples and sand. Ei-
air-dried samples from the Day-15 compost and a
time series of the digester sludges were transferred
the TNT transformation products were spiked into
to 22-mL vials and treated with 10 mL of 0.5 M
the mixtures at concentrations ranging from 25 to
NaOH. The samples were vortex-mixed for three
75 mg/kg. The mixtures were sonicated overnight
3