APPENDIX B: DETERMINATION OF NITROAROMATICS, NITRAMINES, AND NITRATE ESTERS BY SPE AND GC-ECD

Table A2. MDLs obtained when 10 replicate 0.01 g/L 1-L water samples were preconcentrated to 4.0 mL acetonitrile

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APPENDIX B: DETERMINATION OF NITROAROMATICS, NITRAMINES,

AND NITRATE ESTERS BY SPE AND GC-ECD

1.0 SCOPE AND APPLICATION

2.3 GC-ECD determinations

Acetonitrile extracts are directly injected into the

This method is intended for the trace analysis

heated inlet of a gas chromatograph equipped with

of explosives residues in water; it provides gas

an electron capture detector. The analytes are

chromatographic (GC) conditions for the detec-

resolved on a wide-bore fused-silica capillary

tion of the ppb levels using an electron capture

column coated with polydimethylsiloxane.

detector (ECD). All of these compounds are used

as explosives, are by-products of the manufac-

ture of explosives, or are the transformation

3.0 DEFINITIONS

products of explosives. This method is restricted

to use by or under the supervision of analysts

Compound

Abbreviation

CAS* number

experienced in the use of GC-ECD, skilled in the

Octahydro-1,3,5,7-tetranitro-

interpretation of chromatograms, and experi-

1,3,5,7-tetrazocine

HMX

2691-41-0

enced in handling explosive materials. Also,

Hexahydro-1,3,5-trinitro-

each analyst must demonstrate the ability to gen-

1,3,5-triazine

RDX

121-82-4

1,3,5-Trinitrobenzene

TNB

99-35-4

erate acceptable results with this method.

1,3-Dinitrobenzene

DNB

99-65-0

2,4,6-trinitrophenylmethyl-

nitramine

Tetryl

479-45-8

2.0 SUMMARY OF METHOD

Nitrobenzene

98-95-3

2,4,6-Trinitrotoluene

2,4,6-TNT

118-96-7

This method provides two optional proce-

4-Amino-2,6-dinitrotoluene

4-Am-DNT

1946-51-0

dures for preconcentration of low concentration

2-Amino-4,6-dinitrotoluene

2-Am-DNT

35572-78-2

(parts per trillion, or nanograms per liter) of cer-

2,4-Dinitrotoluene

2,4-DNT

121-14-2

tain explosives residues in surface or ground-

2,6-Dinitrotoluene

2,6-DNT

606-20-2

2-Nitrotoluene

2-NT

88-72-2

water. These options are cartridge solid-phase

3-Nitrotoluene

3-NT

99-08-1

extraction and disk solid-phase extraction.

4-Nitrotoluene

4-NT

99-99-0

3,5-Dinitroaniline

3,5-DNA

618-87-1

2.1 Cartridge solid-phase extraction

Nitroglycerine

55-63-0

Pentaerythritoltetranitrate

PETN

78-11-5

For each sample, a Waters Sep-Pak Vac Pora-

pak RDX cartridge is placed on a solid-phase

*Chemical Abstract Service Registry Number

extraction vacuum manifold. The solid phase is

conditioned by passing acetonitrile through each

4.0 INTERFERENCES

cartridge. Then reagent-grade water is pulled

through each cartridge to rinse away the acetoni-

4.1 Sample processing hardware

trile. Next, the analytes are extracted by pulling

Solvents, reagents, glassware, and other sam-

the aqueous samples through cartridges at low

ple processing hardware may yield artifacts

flow rate. Air is then pulled through each car-

and/or elevated baselines, causing misinterpre-

tridge to remove excess water. Finally, the car-

tation of the chromatograms. All of these materi-

tridges are eluted using acetonitrile.

als must be demonstrated to be free from inter-

ference.

2.2 Disk solid-phase extraction

For each sample, an Empore styrene-divinyl

4.2 Detector

benzene reverse-phase sulfonated resin (SDB-

In addition to nitrogenated organics, the ECD

RPS) disk is placed on a vacuum filter apparatus

will respond to other electrophores such as halo-

and preconditioned with acetonitrile. The aceto-

genated and oxygenated compounds. No speci-

nitrile is pulled through each disk, followed by re-

fic compounds have been identified as interfer-

agent-grade water, and then the water sample. Air

ences.

is then pulled through each disk to remove excess

water. Finally, the disks are eluted using acetoni-

4.3 Injector

trile.

The injection-port liner must be deactivated to

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