Patent Grant
8889421
The present invention relates generally to a kit and method for the colorimetric detection of precursors used in the assembly of homemade explosives (HMEs). More specifically, the present invention relates to a bulk HME precursor detection kit and methods of using a kit that is capable of bulk detection of HME precursors, such as urea nitrate, ammonium nitrate and potassium chlorate.
The detection of explosives is an important component of modern warfare, and devices capable of detecting explosive residues are of great importance. In particular, homemade explosives (HMEs) are frequently found in the theatre of war, as HMEs are prepared from components that are easily synthesized from readily available precursor chemicals.
Currently, there are several commercial test kits that have the ability to detect the presence of some precursors commonly used for making HMEs. However, these kits are typically not specifically designed for soldiers performing tactical operations. In particular, most commercial test kits are typically too large, heavy and cumbersome to be practical for tactical operations. Furthermore, soldiers performing tactical operations typically come in contact with bulk quantities of HME precursors. However, the majority of all existing commercial test kits focus solely on trace detection and are not optimized for bulk detection, and hence do not provide a tactical advantage to a soldier in the theater of war. Additionally, most commercial colorimetric test kits are designed to detect most HME precursors, HMEs and military grade explosives all in one test kit. This comprehensive testing approach unfortunately leads to confusion for the end user, an unacceptable level of false positives and negatives, and a decrease in the overall effectiveness of the test kit.
Accordingly, there is a need for an effective bulk HME precursor detection kit that is portable, lightweight, easy to use, low cost, provides focused detection and provides true bulk detection. Further, it would be highly advantageous if the bulk HME precursor detection kit were designed to focus only on detecting primary threat materials found in a specific conflict or theater of operations, thereby reducing confusion for the end user and increasing detection effectiveness and reliability.
The present invention relates generally to a kit and method for the colorimetric detection of precursors used in the assembly of homemade explosives (HMEs). More specifically, the present invention relates to a bulk HME precursor detection kit and methods of using a kit that is capable of bulk detection of HME precursors, such as urea nitrate, ammonium nitrate and potassium chlorate.
Exemplary embodiments of the invention relate to a detection kit for detecting the presence of a bulk homemade explosive (HME) precursor in a sample comprising: at least one vial for holding a dry sample of the HME precursor; at least one nitrate test strip for detecting the presence of nitrates in the sample; at least one reagent for detecting the presence of ureas in the sample; and at least one potassium iodide/starch test strip for detecting the presence of chlorates in the sample.
Additionally, in various embodiments of the detection kit, the nitrate test strip turns purple when nitrate is present in the sample. In further exemplary embodiments, at least one reagent is Ehrlich's reagent. In even further embodiments, the potassium iodide/starch test strip turns blue or black when chlorate is present in the sample. Other aspects of the invention may also feature a detection kit where the nitrate test strip further comprises nitrate reductase. In another aspect of the detection kit, the nitrate test strip further comprises sulfanilamide and N-(1-naphthyl)-ethylene diamine. Other embodiments of the detection kit may also include HCl solution as a reagent.
Other exemplary embodiments of the invention relate to a method of detecting the presence of a bulk HME precursor using a detection kit, including the steps of providing a dry sample suspected of containing bulk HME precursors; mixing the sample with an aqueous solution in a vial; inserting a nitrate test strip to detect for the presence of nitrates in the sample; adding a reagent to the vial to detect for the presence of ureas in the sample; and inserting a potassium iodide/starch test strip to detect for the presence of chlorates in the sample, where the step of inserting the potassium iodide/starch test strip is performed only when the prior steps produce negative results for the presence of nitrates and ureas.
The present invention relates generally to a kit for the colorimetric detection of precursors used in the assembly of homemade explosives (HMEs). More specifically, the present invention relates to a bulk HME precursor detection kit (hereinafter “detection kit”) that is capable of bulk detection of HME precursors, such as urea nitrate, ammonium nitrate and potassium chlorate. The present invention also provides a method of using the detection kit to detect HME precursors.
When the terms “one,” “a,” or “an” are used in this disclosure, they mean “at least one” or “one or more,” unless otherwise indicated.
In accordance with the present invention, an exemplary detection kit capable of detecting various bulk HME precursors, such as urea nitrate, ammonium nitrate and potassium chlorate, is shown in
The present invention is a detection kit and method of using a detection kit that is capable of detecting bulk HME precursors. Examples of HME precursors include nitrate based oxidizers, such as ammonium nitrate and potassium nitrate. Additional examples of HME precursors include urea and urea nitrate, and potassium chlorate.
Nitrate Based Oxidizers
Nitrate based oxidizers represent one type of HME precursor. In an exemplary embodiment, the detection of nitrate based oxidizers may be conducted according to the following chemical reaction scheme:
Step 1.
Nitrate (NO3−)+Nitrate reductase→Nitrite (NO2−)
Step 2.
In step 1 of the above exemplary embodiment, nitrate ions are reduced to nitrite ions with the addition of the enzyme nitrate reductase. The addition of nitrate reductase can be achieved by using nitrate anion detection strips (for example, sold by EMD Chemicals, Inc., Gibbstown, N.J.) or any equivalent commercially available detection strip containing the nitrate reductase.
In step 2, nitrite ions react with the aromatic amine, sulfanilamide, in the presence of an acidic buffer to form a diazonium salt. The diazonium salt then reacts with NED to form a red/violet azo dye.
Urea/Urea Nitrate
Another HME precursor is urea or urea nitrate (hereinafter “ureas”). In an exemplary embodiment of the present invention, the detection kit may be equipped with Ehrlich's reagent to detect the presence of urea or urea salts such as urea nitrate. Ehrlich's reagent is a well-established and characterized reagent that reacts chromatometrically with ureas, and has been used extensively in the determination of ureas in biological fluids, urethane resins, soil, water and feed stocks.
Ehrlich's reagent is composed of 2% 4-(dimethylamino)benzaldehyde and 20% HCl in alcohol (methanol, ethanol, propanols, butanol, pentanol). The reaction of urea or uronium cations with 4-(dimethylamino)benzaldehyde results in (E)-1-(4-(dimethylamino)benzilidene)uronium chloride, which produces a yellow to yellow green color. The yellow color produced by the product of the reaction is due to simple Schiff bases with quinoid resonating structures. An exemplary chemical reaction scheme is as follows:
Potential pitfalls of this method include the suppression of color development due to dilution, as expected for a reversible reaction of this type, and decrease in color relative to hydrochloric acid concentrations either above or below optimal level. Optimal concentrations, solvents and conditions of the Ehrlich's reagent to avoid these pitfalls can easily be ascertained with routine optimization experiments.
Potassium Chlorate
Another HME precursor that may be detected using a detection kit as described is potassium chlorate. The detection of potassium chlorate relies upon the liberation of I2 in solution, which produces an immediate color change to dark red/violet in the presence of chlorate anions. In an exemplary embodiment, the detection of potassium chlorate may be conducted according to the following chemical reaction scheme:
ClO3−+6I−+6H+→Cl−+3I2+3H2O
KClO3+6KI+6HCl→3H2O+7KCl+3I2 (dark red/violet) (blue/black in presence of starch)
In the chemical reaction scheme shown above, the liberation of I2 produces a deep dark color, which is immediate and easily seen. Furthermore, when starch is added, the color is intense blue/black when I2 is liberated. Accordingly, the detection of I2 may be achieved by using potassium iodide/starch test strips (for example, sold by Fisher Scientific, Pittsburgh, P.A.) or any equivalent commercially available detection strip.
In various exemplary detection kits, the test for potassium chlorate may be optimized for the detection of bulk quantities of chlorates and chlorate mixtures with sugar and aluminum. Liquid calcium hypochlorite and household liquid bleach will produce a false positive. Liquid peroxides will immediately produce a black color in these test strips. However, the scope of this test kit is for bulk powders or “prills” found in theater and is not intended for use on liquid samples. The dilute HCl solution required for this test will not ignite potassium chlorate/sugar mixtures and will not result in severe burns to the skin (mild irritation). This chemistry is available in the form of a test strip. Potassium iodide/starch test strips are available from Fisher Scientific.
Detection Kit
Referring to the drawings for the purpose of describing exemplary embodiments of the present invention,
As shown in
Methods of Using
In accordance with the present invention, there is provided a method of using a detection kit as described herein to detect bulk HME precursors.
Step 1: Add one level spoonful of powder to vial. Fill vial to line with water, seal the vial and shake until the sample is dissolved.
Step 2: Insert a nitrate test strip into mixture for 1 second. Nitrate is present if test strip turns light red to dark purple within 5 seconds.
Step 3: Add 5 drops of urea test reagent (e.g., Ehrlich's reagent) to the vial, seal the vial and shake vigorously for 5 seconds. Uronium ions are present if the liquid turns yellow immediately after shaking. Nitrate based fertilizers are present with a positive result for nitrate and a negative result for urea. Urea is present if a positive result for uronium ions and a negative result for nitrate is obtained. Urea nitrate is present if a positive result for uronium ions and a positive result for nitrate is obtained.
Step 4: Insert a chlorate test strip (e.g., potassium iodide/starch) into mixture for 1 second. Remove the test strip and add one drop of HCl directly onto the test strip. Chlorate is present if the test strip turns blue or black within 5 seconds.
In the exemplary embodiment described above, there are five different test result scenarios for possible precursor identification, as shown in Table 1:
As illustrated in Table 1, material identification is determined based on testing for nitrates, ureas and chlorates. As depicted, when only nitrate is detected by a detection kit, the material identification indicates the presence of ammonium nitrate, potassium nitrate or calcium ammonium nitrate containing 27% nitrogen (CAN-27), and the Explosive Ordnance Disposal (EOD) should be alerted. When only uronium ions are detected, the material identification indicates the presence of urea in amounts equivalent to legal fertilizers. Additionally, when only chlorate is detected, the material identification indicates the presence of sodium chlorate or potassium chlorate, and the EOD should be alerted. Further, when none of the three precursors discussed are detected, the sample does not contain nitrates, chlorates or urea in bulk quantities.
The disclosure set forth above is provided to give those of ordinary skill in the art with a complete disclosure and description of how to make and use various embodiments of the invention, and are not intended to limit the scope of what the inventors regard as their invention. Modifications of the above-described modes (for carrying out the invention that are obvious to persons of skill in the art) are intended to be within the scope of the following claims. More specifically, it will be apparent that certain agents which are both chemically and physiologically related may be substituted for the agents described herein while the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention. All publications, patents, and patent applications cited in this specification are incorporated herein by reference as if each such publication, patent or patent application were specifically and individually indicated to be incorporated herein by reference.
Finally, any numerical parameters set forth in the specification and attached claims are approximations (for example, by using the term “about”) that may vary depending upon the desired properties sought to be obtained by the embodiments of the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of significant digits and by applying ordinary rounding.
The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefore.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3446599 | Shand | May 1969 | A |
| 3531254 | Okuda | Sep 1970 | A |
| 3802842 | Lange et al. | Apr 1974 | A |
| 3817705 | Schmitt et al. | Jun 1974 | A |
| 3826620 | Davis et al. | Jul 1974 | A |
| 4595430 | Baker | Jun 1986 | A |
| 4690902 | Bitsch | Sep 1987 | A |
| 4788039 | Glattstein | Nov 1988 | A |
| 4904605 | O'Brien et al. | Feb 1990 | A |
| 4938926 | Reiss | Jul 1990 | A |
| 5100621 | Berke et al. | Mar 1992 | A |
| 5296380 | Margalit | Mar 1994 | A |
| 5480612 | Margalit | Jan 1996 | A |
| 5648047 | Kardish et al. | Jul 1997 | A |
| 6613576 | Rodacy et al. | Sep 2003 | B1 |
| 7410612 | Carrington | Aug 2008 | B1 |
| 7829020 | Pagoria et al. | Nov 2010 | B2 |
| 7846740 | Amisar | Dec 2010 | B2 |
| 8377713 | Miller et al. | Feb 2013 | B2 |
| 20050287036 | Eckels et al. | Dec 2005 | A1 |
| 20060084176 | Almog | Apr 2006 | A1 |
| 20090029480 | Loane | Jan 2009 | A1 |
| 20100000882 | Wang et al. | Jan 2010 | A1 |
| 20120003746 | Amisar | Jan 2012 | A1 |
| Number | Date | Country |
|---|---|---|
| WO 7900122 | Mar 1979 | WO |
| Entry |
|---|
| Chrostowski, J. E. et al, Arson Analysis News 1981, 5, 14-18. |
| Synthesis procedure for azocoupling benzene diazoniuim chloride with 2 naphthol to form 1-phenylazo-2-naphthol Mar. 2006, 6 pages, downloaded from http://www.oc-praktikum.de/nop/en/instructions/pdf/1017—en.pdf. |
| Booklet titled “Identifying Unknown Chemicals in Science Labs” Sep. 2009, 6 pages, published by the Florida Department of Environmental Protection. |
