and in a biotic medium such as urine (Yucang et
a viewing box was obtained from UVP, Inc., in San
al. 1991, Steuckart et al. 1994). Classical or conven-
Gabriel, California.
tional TLC served to provide more of a qualita-
tive determination of explosives, whereas mod-
Chemicals and reagents
ern TLC or HPTLC provides both qualitative and
Analytical standards for TNT, TNB, tetryl, 2,4-
quantitative results. The advantage of modern
DNT, 4-A-DNT, 2-A-DNT, RDX, HMX, NG, and
TLC is sensitivity, providing very low limits of
PETN were prepared from Standard Analytical
detection. However, the initial capital cost of the
Reference Materials (SARM) obtained from the
necessary instrumentation can be high, and usage
U.S. Army Environmental Center, Aberdeen Prov-
of highly sensitive equipment is not ideal for field
ing Ground, Maryland.
situations unless the equipment is housed in a
Visualizing chemicals and reagents consisting
mobile laboratory. The conventional TLC meth-
of p-(diethylamino)benzaldehyde (DEAB), p-
ods are not as sensitive, but because of very simple
(dimethylamino)benzaldehyde (DMAB), titanium
equipment requirements, they can be used in the
(III) chloride (TiCl3), ethylenediamine (EDA), po-
field without significant modifications, at reason-
tassium permanganate (KMnO 4), sodium
able cost.
periodate (NaIO4), diphenylamine (DPA), n-(1-
naphthyl)ethylenediamine dihydrochloride and p-
(dimethylamino) cinnamaldehyde (DMACA), ace-
Objective
The objective of this work is to evaluate the use
tic acid, and zinc were purchased from Aldrich
of conventional TLC as an adjunct to current on-
Chemical Co., Milwaukee, Wisconsin. TNT EnSys
site colorimetric methods for TNT, RDX, and re-
developer reagent was obtained from EnSys, Inc.,
lated compounds. The most popular colorimetric
Research Triangle Park, North Carolina. Potassium
methods often cannot readily distinguish among
hydroxide, hydrochloric acid, hexane, acetonitrile,
the various polynitroaromatic compounds that
and sulfanilic acid were purchased from Baker Inc.,
respond to the TNT test, or the various nitramines
Phillipsburg, New Jersey. Sodium hydroxide, so-
and nitrate esters that respond to the RDX test.
dium nitrite, petroleum ether, stoddard solvent,
This work evaluates the ability of TLC to separate
and ethanol were purchased from Fisher
TNT and the other common polynitroaromatic
Scientifics, Fair Lawn, New Jersey. Butyl alcohol
compounds, and RDX and the other commonly
and dimethylsulfoxide (DMSO) were obtained
encountered nitramines and nitrate esters in a cost-
from Mallinckrodt, St. Louis, Missouri. Xylene was
effective and timely manner.
furnished by MCB Reagent, Cincinnati, Ohio, and
sulfanilamide was from Eastman Kodak Co.,
Rochester, New York. Acetone and chloroform
MATERIALS AND METHODS
were from EM Science, Gibbstown, New Jersey,
and Burdick & Jackson, Muskegon, Michigan, re-
Instrumentation and equipment
spectively. Finally, the Hach NitriVer3 powder pil-
A basic thin-layer chromatography starter kit
lows were from Hach Co., Loveland, Colorado.
was purchased from Alltech Associates, Inc.
Commercial-grade solvents were purchased
(Deerfield, Illinois). The starter kit included the
following: a 20- 20-cm TLC tank with glass lid,
from local paint and hardware stores. These sol-
20- 20-cm tank liners, microcap (microcapillary)
vents consisted of Sunnyspec paint thinner, Ster-
ling Lynsol, Sterling Thin-X (red), Sterling VM &
dispensers (for sample spotting), disposable spray
P naphtha, Savogram deglosser, Parks VM & P
box, spotting template, reagent spray unit with
glass jar, and 20- 20-cm Adsorbosil Plus 1 TLC
naphtha, Recordsol paint thinner, PPG Industries
Duracryl, Sterling acetone, Ace paint thinner,
plates. Additional glass-backed plates consisting
of EM silica gel 60 F254 (20 20 cm, 250 m), EM
Woolworth-brand 70% isopropanol, Sterling sol-
vent alcohol, and 3M general purpose adhesive
silica gel 60 F254 with preconcentration zone (20
20 cm, 250 m), EM silica gel 60 with
cleaner. Mobil gasoline with octane 93 was pur-
preconcentration zone (20 20 cm, 250 m), EM
chased from a local gas station.
HPTLC silica gel 60 F254 with preconcentrated and
prechanneled zones (10 10 cm, 200 m), and
Preparation of visualizing agents
TiCl3 reagent
Adsorbosil HPTLC with phosphor and
preconcentrated zone (10 10 cm, 150 m) were
In a 50-mL volumetric flask, 5 mL of aqueous
TiCl3 solution (10% TiCl3 in 2023% HCl) is com-
purchased from EM Science, Gibbstown, New Jer-
bined with 5 mL of 2 N HCl and the solution is
sey. A multiband (254 and 366 nm) UV lamp with
3
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