Vladimír PITSCHMANN, Emil HALÁMEK, Zbyněk KOBLIHA
Abstract: Simple detection of adamsite (irritating warfare agent) in air is described. Two different methods using detector
tubes based on substitution-type reactions were developed. The first method is based on electrophilic reaction of adamsite
with sodium nitrite in acidic solution which results in red nitroso or isonitroso derivate. The second method is based on
nucleophilic reaction of adamsite with ammonium thiocyanate, affording a yellow product. The detection limit for
adamsite in air is 0.5 µg for the first described method and 5 µg for the second. Visual evaluation of detector tubes is
based on intensity of color developed on the indication layer.
Keywords: Adamsite, detector tubes, sodium nitrite, thiocyanates.
code labeling DM] is a warfare agent of the first
generation, with irritating effect on the upper
respiratory tract (for selected properties see Tab. 1).
Tab. 1 Some selected properties of adamsite 
Boiling point, °C
Melting point, °C
19 300 (0 °C), 26 000 (20 °C),
acetone, furfural, hexane
(insoluble in water)
22 – 150
11 000 – 35 000
The first compound of this type is 10-bromo-
Bayer works in Germany. Adamsite itself was
synthesized two years later by German chemist
Heinrich Wieland and at the end of World War I
independently developed by a team of American
chemists at Illinois University, headed by Roger
Adams who suggested its possible military use.
During the World War II, its non-nitrogen analogue
excelsior (5-chloro-10-methylacridarsine) was
introduced in Germany. Six thousand one hundred
tons of adamsite have been stockpiled by the Soviet
Union, 300 t by the U.S.A. and 3 700 t by Germany.
In March 1939, the Czechoslovak Army possessed
one ton of adamsite. At present, this substance is
subject to the Chemical Weapons Convention.
Only scarce data on the military use of adamsite
are at disposal. It was probably first deployed by
Italian troops already before the end of World War I.
It was used by British intervention forces during the
Russian civil war and by the American Army in
Vietnam. In all these cases adamsite proved to be an
insidious and very effective warfare agent. It is also
known that for its incapacitating effect adamsite was
used by police forces as riot controlling agent. At
present, it may be misused by terrorists. Thus, e.g.,
an information was disclosed about plans of some
militant Islamic groups to use adamsite against
selected embassies and state buildings in Belgium
. For this reason, investigation on chemical
analysis of adamsite and structurally similar
compounds cannot be underestimated.
The practically only warfare state of adamsite is
a toxic smoke capable of attacking efficiently the
upper respiratory tract. This fact significantly limits
the potentialities of technical means for detection of
adamsite in air, in which also detection tubes play an
unsubstitutable role. As regards the reaction
principles, only a few functional variants of
detection tubes are known. A simplest device
contains glass wool for effective trapping of the
aerosol, and an ampoule filled with sulfuric acid
which with adamsite affords red coloration of
unknown composition . A similar reaction is also
produced by action of formic acid (on heating) and
perchloric acid which gives a pink colored product
. This system is little selective and therefore
a detection tube has been developed that contains an
ampoule with mercury(I) nitrate solution in
concentrated sulfuric acid. The presence of adamsite
manifests itself by a characteristic green product of
unknown composition. A detection tube based on
this principle has been introduced in the
Czechoslovak Army (labeled by two white stripes)
and even today a similar device is offered by the
Russian Krismas company under specification IT-
(and CR) has been described in the literature that
contains silica gel impregnated with 4-chloro-5,7-
dinitrobenzofurazane . Another suitable reaction
is based on formation of red sodium salt of the
nitration product. Adamsite is first nitrated with
concentrated nitric acid and the formed nitro
derivative is then treated with concentrated solution
of sodium hydroxide to give the red sodium salt .
This reaction has also been utilized for colorimetric
determination of adamsite at 530 nm  but its use
in a detection tube has not been described. Of less
used reactions, one may mention the reaction of
adamsite with HI under formation of diphenylamine
which is separated by distillation and proved e.g. by
blue coloration on reaction with nitrates in
concentrated sulfuric acid .
The aim of the present study is to describe the
preparation, properties and use of two types of
detection tubes for detection of adamsite in air,
based on electrophilic or nucleophilic substitution
reactions affording colorimetrically (visually)
evaluated colored products.
2.1 Chemicals and instruments
The indicator packings and detection solutions
ammonium thiocyanate, sodium nitrite, hydrochloric
acid 35% (all p.a., Sigma – Aldrich), and anhydrous
ethanol (Riedel-de Haën). The detection solution for
the reference tubes was prepared with mercury(I)
nitrate and 96% sulfuric acid (p.a., Sigma-Aldrich).
The employed silica gel (Grace, Germany), had
particle size 0.5-0.7 mm, specific surface 200 m
and 120 % sorption capacity (H
O). The coating
components were furnished by the Tejas company
(Jablonec, Czech Republic).
The detector tubes were tested using 10-chloro-
5,10-dihydrophenarsazine (NBC Defence Institute,
University of Defence, Brno) of 96.3 % purity, as
checked by classical iodometric method .
The detector tube contained an indication packing
(layer) and a glass ampoule with detection solution.
The indication layer consisted of silica gel which
had been purified by boiling with dilute hydrochloric
acid, washing with distilled water until the washings
were neutral, and which was finally activated by
The purified silica gel (100 g) was impregnated
with 110 ml of 1% aqueous solution of sodium
nitrite. The mixture was dried, first on air until the
material became loose and then in a drying box at 90
to 110 °C for 2 hours.
The thus-obtained milky white indication packing
was poured into a glass tube to form 10 mm high
layer and fixed by polyethylene starlets and a
polyamide net. Finally, a glass ampoule
containing 20% hydrochloric acid was inserted and
the tube was hermetically flame-sealed. Detector
tubes construction – see Figure 1.
Fig. 1 Construction of detector tubes
The detector tube contained a carrier and a glass
ampoule with detection solution. Activated purified
silica gel was employed as the carrier; the detection
solution consisted of 5% ammonium thiocyanate
solution in ethanol. Other construction elements
were the same as described for detector based on
Preparation of reference detector tubes
The reference detector tube contained a carrier
Activated purified silica gel was employed as the
carrier; the detection solution consisted of 0.1%
solution of mercury(I) nitrate in concentrated
sulfuric acid. The remaining construction elements
were the same as described for the newly devised
Testing of detection tubes
The detector tube was opened by breaking both
solution of adamsite of concentration 5, 25, 50, 150,
250, 500 and 1500 µg.ml
indication layer using a micropipette. Then, 1 dm
using a manual air pump Universal 86 (Kavalier
Votice, Czech Republic). The ampoule was crushed
with a metal spike and the detection solution was
thoroughly shaken down onto the carrier. The
change in coloration of the indication layer (carrier)
was evaluated visually.
In the search for suitable color reactions of
use of the known fact that polyvinylcarbazole 
or indole  in an acidic medium afford deeply
colored nitroso products on reaction with nitrite
ions. A similar reaction also takes place with
adamsite. The devised detector tube is based on
formation of an orange to red colored product,
probably a nitroso or isonitroso derivative, formed in
an electrophilic substitution reaction of adamsite
with nitrous acid arising by treatment of sodium
nitrite with hydrochloric acid:
compounds (eg diphenylchlorarsane) react with
sodium thiocyanate under formation of colored
substances . With the mentioned nucleophilic
reagent, adamsite affords a yellow product, probably
phenarsazine thiocyanate. The probable reaction
course may be represented by the following reaction
Both the devised substitution reactions take place
conditions. In the case of the nitrosation reaction that
takes place in the presence of acids, the ampoule
with 20% hydrochloric acid ensures sufficient
stability of the reaction medium. The reaction of
adamsite with thiocyanates requires no special
adjustment of reaction conditions. The high rate of
both the substitution reaction types makes it possible
to practically immediately evaluate the color change
coloration is stable.
The detection limit for the sodium nitrite method
amounts to 0.5 µg of adamsite, for the ammonium
thiocyanate method it is 5 µg. The results obtained
(Tab. 2) can be interpreted so that for taking 1 dm
sample of contaminated air, under assumption of
adamsite aerosol will reach 0.5
reference tube, silica gel instead of glass wool was
employed as the carrier to ensure comparable
Tab. 2 Results of tests with detector tubes for
This change results in variable coloration of the
reference tube we may regard 1 µg of adamsite
which gives rise to still perceivable green coloration.
The orange coloration at lower concentrations has to
be ascribed to the action of concentrated sulfuric
The course and results of the tests are not
influenced by harmful substances, commonly
present in the atmosphere. The sodium nitrite
detector tube may exhibit a color response in the
presence of some aromatic amines or hydroxy
compounds. Thus, e.g., with phenol it shows a red
coloration as the result of the Liebermann reaction
. Substitution reactions similar to those of
adamsite are not known for any of the known
warfare agents (except for diphenylchlorarsane) or
other compound of military significance.
All the devised reagents, used as detection
solutions or immobilized on a carrier, are stable.
This makes possible a production of detector tubes
of long lifetime and usability.
The proposed detector tubes are suitable primarly
standard equipment of the combined and special
chemical units of Czech and Slovak military. The
detector tubes can also be used in new semi-
automatic chemical detector CHP-5, which recently
 STŘEDA, L., HALÁMEK, E., KOBLIHA, Z.:
úřad pro jadernou bezpečnost, 2004, s. 84. ISBN
 On the street. ASA Newsletter, 2003, vol. 96,
ní obrany, 1954, s. 39, 62.
TUŠAROVÁ, I., KOBLIHA, Z.: Oritest, Pra-
U1. Int. Cl. G 01 N 21/78. 2005.
AMELIN, V. G.: Chemical Test Methods of
Analysis. 1-st ed. Amsterdam: Elsevier,
2002, pp. 248, 268. ISBN: 0-444-50261-0.
 EVGEN´EV, M. I., GARMONOV, S. YU.,
DRUZHININ, A. .A: Test Method for the
Determination of Toxic Irritants in Air. J. Anal.
Chem., 2003, vol. 58, p. 485.
Band 2. 2. Auflage. Berlin: Militärverlag der
DDR, 1977, s. 344.
 FRANKE, S.: Lehrbuch der Militärchemie.
Band 2. 2. Auflage. Berlin: Militärverlag der
DDR, 1977, s. 349.
bojových otravných látek. 1. vyd. Praha: SNP,
carbazole with nitrogen dioxide and its
application for the detection of nitrogen
dioxide. Chem. Lett., 1977, pp. 237-240.
 ANDONOVSKI, B. S., STOJKOVIČ, G. M.:
Spectrophotometry study of the reaction of
indole with nitrite ions in hydrochloric acid.
Bulletin of the Chemists and Technologists of
Macedonia, 2002, vol. 21, pp. 177-185.
Braunschweig: Friedr. Vieweg & Sohn, 1935,
GASPARIČ, J.: A critical investigation of the
vol. 90, pp. 367-386.
Oritest spol. s r.o.
150 00 Praha
Univerzita obrany Brno
Sídliště Víta Nejedlého
682 03 Vyškov