picramic acid (2-amino-4,6-dinitrophenol) by
color-forming reagents. Quantification was pos-
adapted bacteria under the anaerobic conditions
sible using a photodensitometer (Wyman et al. 1979).
that might be found at some waste sites. This com-
Contemporary analytical methods for the de-
pound has ten times the mutagenicity of picric
termination of picrate in the environment have
acid (Wyman et al. 1979). The toxic effects on
focused on extraction, separation from matrix com-
aquatic organisms are also greater for picramic
ponents and analysis in the laboratory. U.S. Geo-
acid than for picric acid (Goodfellow et al. 1983).
logical Survey methods (Goerlitz 1979) used ben-
Picramic acid is also a mammalian metabolic trans-
zene or methylene chloride for extraction from soils
formation product of picric acid (Barral 1915,
and water, followed by concentration, solvent ex-
Wyman et al. 1992) and is excreted in the urine. It
change and reverse-phase, high-performance liq-
will be introduced into the environment if picric
uid chromatography (RP-HPLC) with eluents con-
acid is ingested.
taining an ion-pairing reagent. U.S. Army Envi-
Unlike many of the other high explosives that
ronmental Center (USAEC) Method LW-13 (1989)
are no longer manufactured and that present en-
used a 10% aqueous methanol solution for extrac-
vironmental clean-up problems unique to the mili-
tion from soil, followed by analysis by RP-HPLC.
tary, picric acid is a ubiquitous industrial chemi-
Methylene chloride was used to extract picric acid
cal. It is widely used as a metal-etching chemical
from acidified water samples, followed by con-
and as feed stock in many processes in the dye,
centration, solvent exchange and analysis by RP-
leather and glass industries (Wyman et al. 1992).
HPLC using a buffered, acidic aqueousacetoni-
Picrate is also an environmental transformation
trile eluent. Midwest Research Institute methods
product of tetryl, another obsolete military explo-
(Conrad 1990a,b) used ion-pairing and solid-phase
sive (Kayser et al. 1984). Picrate was detected in a
extraction of picrate ion pairs from water, followed
leachate from soil columns spiked with tetryl
by ion-pair analysis using HPLC with a polycyclic
(Kayser and Burlinson 1988) and was recently de-
aromatic hydrocarbon column. Picrate was ex-
tected as a transformation product of tetryl in wa-
tracted from soils with an acidic methanolwater
ter (Jenkins et al. 1995). A rapid screening method
mixture and analyzed by RP-HPLC using ion-pair-
for the detection of picrate in soil and water will
ing conditions. Lloyd (1985) used RP-HPLC with
have broad utility. Indications are that it is not
a buffered, acidic aqueousmethanol eluent to de-
degraded in the environment, either biologically
tect picrate and other high explosives from foren-
or photochemically (Layton et al. 1987), although
sic samples. Voyksner and Yinon (1986) used
some strains of adapted organisms may make
thermospray HPLC-mass spectrometry with
bioremediation a possibility (Wyman et al. 1979,
chemical ionization to analyze acetone wipes of
Lenke and Knackmuss 1992).
skin contaminated with six high explosives, in-
cluding picric acid. Munder et al. (1990) devel-
oped a capillary supercritical fluid chromato-
Previous analytical methods
Detection of picric acid has been a goal of ana-
graphic technique that could resolve picric acid
lytical chemists since the early 20th century, when
from other explosives in complex mixtures.
malingerers ingested picric acid to mimic the
Ammonium picrate and picric acid are not cur-
symptoms of jaundice to avoid military service.
rently target analytes in SW846 Method 8330
Early detection schemes used colored precipitates
(USEPA 1990). If the standard conditions for ex-
(Barral 1915), colored solvent interfaces (Rodillon
traction and analysis of explosives in soil from
1915) or colored solutions (Ydrac 1916) to identify
Method 8330 are used, picrate would be extracted
picric acid and its metabolic by-product, picramic
by overnight sonication in acetonitrile but would
acid. In 1923, Deniges investigated the unique
not be retained by the RP-HPLC with a 50% aque-
color-changing behavior of the picric acidpicrate
ousmethanol eluent. Method 8330 for water uses
system in aqueous and strongly acidic, organic
the same separation, and hence, picrate would not
solutions.
be detected using this protocol.
Forensic analysts have been required to iden-
A field screening method for Dinoseb (2-sec-
tify and quantify picric acid in complex mixtures
butyl-4,6-dinitrophenol, CAS 88-85-7) in soil was
of other nitroaromatic explosives. Paper chroma-
developed by Anderson et al. (1993). Dinoseb is a
tography (Barnabas 1954, Colman 1962) or thin-
pesticide that is structurally similar to picric acid
layer chromatography (Parihar et al. 1966, Bagnato
but is less acidic and more hydrophobic (Fig. 2). In
and Grasso 1986) were used to separate picric acid
this method, soil is extracted with methylene chlo-
from other explosives, where it was detected by
ride and the extract is mixed with Florisil, a basic,
2
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