Ammonium Nitrate Samples Research Articles

Source determination of homemade ammonium nitrate using ATR-FTIR spectroscopy, trace elemental analysis and chemometrics

Ammonium nitrate (AN) is one of the most significant chemicals used within industry, but has also seen frequent use by terrorist and extremist groups as it can be easy to source, prepare and implement in improvised explosive devices (IEDs). AN typically exists as fertiliser or explosive grade but can also be prepared from a range of commercial products. For the first time, the synthesis, characterisation and source determination of AN prepared from alternative products and mixtures has been reported. Analysis with attenuated total reflectance fourier-transform infrared spectroscopy (ATR-FTIR) revealed that AN samples could be separated into two distinct classes termed as pure form, which included different grades of AN, or as homemade, which included AN prepared from commercial products. Linear discriminant analysis (LDA) was used to develop classification models that predicted the correct source of 100 % of pure form samples and 80 % of homemade samples within an independent dataset. Trace elemental analysis using inductively coupled plasma mass spectrometry (ICP-MS) proved to have greater discriminatory power as full separation of samples was achieved by principal component analysis (PCA). The concentrations of ten elements were used to discriminate between products including B, Ti, Mn, Ni, Cu, Se, Rb, Sr, Ba and U. Furthermore, LDA revealed the model generated was able to correctly match all validation samples to their source. This work contributes to the forensic intelligence of AN and demonstrates how ATR-FTIR and ICP-MS can be used to potentially identify and discriminate between different grades, precursors and brands.

The Effect of Variation of Raw Material Ratio on Hydrogel Based on K-Carrageean - Acrylamide as a Carrier of Ammonium Nitrate Fertilizer

Hydrogels based on natural polymers such as carrageenan are currently being developed to improve efficiency in agriculture. By enriching hydrogels with fertilizers, they will be released slowly into the soil. Enrichment of fertilizers on carrageenan-based hydrogels was carried out and analyzed with the response of swelling ability, gel fraction value of grafting degree, to the hydrogel's ability to release the fertilizer trapped in it. Carrageenan is used because its use as a natural polymer has not been widely explored, especially in the non-food sector. The results showed that the average swelling value of carrageenan-based hydrogel to ammonium nitrate solution ranged from 750.00% - 1,633.33%. The gel fraction values obtained ranged from 74.06% to 87.51%, and the degree of grafting ranged from 85.33% to 93.59%. These values indicate a relatively high degree of tissue density and grafting of acrylamide monomer on carrageenan, which means that the carrageenan:AAm based hydrogel has strong mechanical properties. The ability to release ammonium nitrate samples from the hydrogel carrageenan-based has a value ranging from 8.86% to 44.92% in five days of observation. Interpretation of the test results, the best ratio of carrageenan:AAm is 1:1, due to its relatively low release value but still has good swelling and mechanical properties.Keywords: Hydrogel; Carrageenan; Acrilamyde; Fertilizer release

Determination of stable nitrogen isotopic ratios of nitrate ions in ammonium nitrate.

Ammonium nitrate (AN) is one of the most commonly used explosives in criminal cases. The comparison and source-tracing of AN is important for investigation of attribution and fingerprinting of an explosive used at different events. The stable isotope signature of AN is an important index for comparison and tracing. However, the characteristics of the stable nitrogen isotopic ratios of AN (δ15 NNH4NO3 ) alone are not sufficient to achieve a fine comparison between different AN samples. To increase the comparison index and further improve the discriminability between stable nitrogen isotopic ratios of different ANs, a method of isolation and analysis of nitrate ions in AN was established using stable-isotope-ratio mass spectrometry (IRMS). The method was based on the principle that strong alkali react with AN to produce ammonia and nitrate. After the isolation, stable nitrogen isotopes of nitrate ions (δ15 NNO3 ) were obtained using IRMS, and then the stable nitrogen isotopes of ammonium ions from AN (δ15 NNH4 ) was calculated according to the principle of mass balance. The results show that the method is effective for the isolation of nitrate ions without notable isotope fractionation. The developed method was applied to analyze and discriminate AN samples from eight different cities in China. Three samples out of the initial eight AN samples with similar δ15 NNH4NO3 values were further distinguished by their δ15 NNH4 and δ15 NNO3 values. The isolation and stable-nitrogen isotopic analysis method developed for nitrate ions in AN is simple and effective, thereby increasing the discriminability of the stable isotope ratios in AN.

Purification of ammonium nitrate via recrystallization for isotopic profiling using isotope ratio mass spectrometry

Stable-isotope analysis of ammonium nitrate (AN) plays an important role for comparing and tracing the sources of AN samples. Numerous studies have reported the application of isotope ratio mass spectrometry (IRMS) for the stable-isotope analysis of AN. However, in real cases, AN is often mixed with liquid hydrocarbons, organic explosives, wood flour, and sodium chloride. Therefore, the purification of AN samples prior to IRMS analysis is essential. Based on the different solubilities of AN at different temperatures, AN samples were purified by recrystallization. The results show that recrystallization can effectively purify AN, and the isotope fractionation effect caused by recrystallization increases the stable-isotope ratio (δ15N increased by 0.07–0.14‰, δ18O increased by 0.15–0.33‰, and δ2H increased by 4.61–18.16‰). The change of δ15N and δ18O were close to the standard deviation values, and did not affect the differentiation of AN. δ2H was deemed unsuitable for AN differentiation, owing to isotopic exchange during recrystallization. Eight AN samples from different cities and four AN samples produced in different years and batches from the same manufacturer in China were analyzed after recrystallization. Both groups of AN samples could be distinguished by combining the nitrogen and oxygen isotope ratios. Therefore, recrystallization can be used as a means of AN purification for the accurate determination of AN in ammonium nitrate fuel oil and explosive residues.

Headspace analysis of ammonium nitrate variants and the effects of differing vapor profiles on canine detection

Canines continue to be one of the most frequently deployed tool in the detection of explosives, and particularly homemade explosives (HMEs), in part, due to the ease in training to new HME materials as threats arise. The majority of HMEs encountered contain ammonium nitrate (AN), and previous research has measured the release of ammonia from AN, and found that the ammonia vapor concentration varies with form, purity, and environment, but this is has not been correlated to canine detection proficiency. In this research, the headspace analysis of AN variants was carried out using solid phase microextraction (SPME) with gas chromatography/mass spectrometry (GC/MS). Ammonia vapor from the AN was extracted using on-fiber derivatization, while the presence of other volatiles in the headspace of these variants were also characterized by a traditional SPME extraction. These results were correlated to canine testing, where canines previously trained in odor detection were provided laboratory-grade AN for odor imprinting, after which they were to locate other AN variants in a series of simple detection tasks. Headspace analysis showed variations in both the amount of ammonia as well as other volatile compounds in the headspace of the various AN samples, as well as changes in the vapor profiles due to changing environmental conditions. Canine data indicated that the differences in the headspace profiles of the samples may confound detection when canines were trained on laboratory-grade AN alone, while increased ammonia vapor availability from certain samples may have improved detection by this group of canines.

Isotopic and elemental profiling of ammonium nitrate in forensic explosives investigations

Ammonium nitrate (AN) is frequently encountered in explosives in forensic casework. It is widely available as fertilizer and easy to implement in explosive devices, for example by mixing it with a fuel. Forensic profiling methods to determine whether material found on a crime scene and material retrieved from a suspect arise from the same source are becoming increasingly important. In this work, we have explored the possibility of using isotopic and elemental profiling to discriminate between different batches of AN. Variations within a production batch, between different batches from the same manufacturer, and between batches from different manufacturers were studied using a total of 103 samples from 19 different fertilizer manufacturers. Isotope-ratio mass spectrometry (IRMS) was used to analyze AN samples for their 15N and 18O isotopic composition. The trace-elemental composition of these samples was studied using inductively coupled plasma–mass spectrometry (ICP–MS). All samples were analyzed for the occurrence of 66 elements. 32 of these elements were useful for the differentiation of AN samples. These include magnesium (Mg), calcium (Ca), iron (Fe) and strontium (Sr). Samples with a similar elemental profile may be differentiated based on their isotopic composition. Linear discriminant analysis (LDA) was used to calculate likelihood ratios and demonstrated the power of combining elemental and isotopic profiling for discrimination between different sources of AN.

DNA damage caused by inorganic particulate matter on Raji and HepG2 cell lines exposed to ultraviolet radiation

Epidemiological studies have correlated exposure to ultraviolet-irradiated particulate matter with cardiovascular, respiratory, and lung diseases. This study investigated the DNA damage induced by two major inorganic particulate matter compounds found in diesel exhaust, ammonium nitrate and ammonium sulfate, on Burkitt's lymphoma (Raji) and hepatocellular carcinoma (HepG2) cell lines. We found a dose-dependent positive correlation of accumulated DNA damage at concentrations of ammonium nitrate (25μg/ml, 50μg/ml, 100μg/ml, 200μg/ml, 400μg/ml) with ultraviolet exposure (250J/m2, 400J/m2, 600J/m2, 850J/m2), as measured by the comet assay in both cell lines. There was a significant difference between the treated ammonium nitrate samples and negative control samples in Raji and HepG2 cells (p<0.001). Apoptosis was shown in Raji and HepG2 cells when exposed to high concentrations of ammonium nitrate (200μg/ml and 400μg/ml) for 1h in samples without ultraviolet exposure, as assessed by the comet assay. However, the level of apoptosis greatly diminished after ultraviolet exposure at these concentrations. Over a 24h period, at intervals of 1, 4, 8, 12, 18, and 24h, we also observed that ammonium nitrate decreased viability in Raji and HepG2 cell lines and inhibited cell growth. Ammonium sulfate-induced DNA damage was minimal in both cell lines, but there remained a significant difference (p<0.05) between the ultraviolet radiation treated and negative control samples. These results indicate that the inorganic particulate compound, ammonium nitrate, induced DNA strand breaks at all concentrations, and indications of apoptosis at high concentrations in Raji and HepG2 cells, with ultraviolet radiation preventing apoptosis at high concentrations. We hypothesize that ultraviolet radiation may inhibit an essential cellular mechanism, possibly involving p53, thereby explaining this phenomenon. Further studies are necessary to characterize the roles of apoptosis inhibition induced by DNA damage caused by inorganic particulate matter.

Isolation and stable nitrogen isotope analysis of ammonium ions in ammonium nitrate prills using sodium tetraphenylborate

Because of the threat of bombings using improvised explosives containing ammonium nitrate (AN), law enforcement and intelligence communities have been interested in stable isotope techniques for tracking and discriminating AN sources. Separate analysis of the AN component ions ammonium and nitrate would add discriminatory power to these techniques. Ammonium ions in dissolved AN solution were isolated from samples by precipitation using sodium tetraphenylborate solution. We tested the isolation of ammonium from nitrates using solutions of ammonium and nitrate salts with different (15)N/(14)N isotope ratios. Ammonium tetraphenylborate and AN were separately analyzed for their (15)N/(14)N isotope ratios using EA-ConFlo-IRMS, and the (15)N/(14)N isotope ratios of the nitrate ions were calculated using mass balance. Ammonium and nitrate nitrogen isotope ratios were plotted as two separate variables. Isolation of ammonium precipitate from solutions containing dissolved nitrates did not influence the nitrogen isotope ratios of test ammonium salts. A survey set of 42 AN samples showed that the ammonium and nitrate (15)N/(14)N isotope ratios were not significantly correlated, and the paired mean differences were not statistically significant. Both ammonium and nitrate were depleted in (15)N relative to their theoretical atmospheric sources. Isolation of the ammonium ion from AN adds another dimension for the discrimination of forensic AN samples. This technique using sodium tetraphenylborate is robust and does not require specialized equipment. Our observations indicated that ammonium nitrogen and nitrate nitrogen have independent sources of isotopic variation.

Surface-Enhanced Raman Scattering Detection of Ammonium Nitrate Samples Fabricated Using Drop-on-Demand Inkjet Technology

The United States Army and the first responder community are increasingly focusing efforts on energetic materials detection and identification. Main hazards encountered in theater include homemade explosives and improvised explosive devices, in part fabricated from simple components like ammonium nitrate (AN). In order to accurately detect and identify these unknowns (energetic or benign), fielded detection systems must be accurately trained using well-understood universal testing substrates. These training substrates must contain target species at known concentrations and recognized polymorphic phases. Ammonium nitrate is an explosive precursor material that demonstrates several different polymorphic phases dependent upon how the material is deposited onto testing substrates. In this paper, known concentrations of AN were uniformly deposited onto commercially available surface-enhanced Raman scattering (SERS) substrates using a drop-on-demand inkjet printing system. The phase changes observed after the deposition of AN under several solvent conditions are investigated. Characteristics of the collected SERS spectra of AN are discussed, and it is demonstrated that an understanding of the exact nature of the AN samples deposited will result in an increased ability to accurately and reliably "train" hazard detection systems.

Abstract 1790: Mutagenic effects of inorganic particulate matter on Raji and HepG2 cell lines exposed to ultraviolet radiation.

Abstract Epidemiological studies have correlated exposure to ultraviolet-irradiated particulate matter with cardiovascular, respiratory, and malignant lung diseases. This study investigated the DNA damage induced by two major inorganic particulate matter compounds found in diesel exhaust, ammonium nitrate and ammonium sulfate on Burkitt's lymphoma (Raji) and hepatocellular carcinoma (HepG2) cell lines. We found a dose-dependent positive correlation of accumulated DNA damage in concentrations of ammonium nitrate and ammonium sulfate (25 μg/ml, 50 μg/ml, 100 μg/ml, 200 μg/ml, 400 μg/ml) with ultraviolet exposure (250 J/m2, 400 J/m2, 600 J/m2, 850 J/m2), as measured by the Comet Assay in both cell lines. There was a significant difference between the treated ammonium nitrate samples and negative control samples in Raji and HepG2 (p &amp;lt; 0.001). Apoptosis was shown in Raji and HepG2 cells when exposed to high concentrations of ammonium nitrate (200 μg/ml, 400 μg/ml) for 1 hour in samples without ultraviolet exposure, as assessed by the Comet Assay. However, the quantity of apoptotic cells greatly diminished after ultraviolet exposure at these concentrations. To further investigate and clarify the underlying mechanisms, we used Annexin V to quantify apoptosis. Flow Cytometry confirmed the results shown by the Comet Assay; ultraviolet exposure diminished apoptosis in ammonium nitrate-induced DNA damage in both Raji and HepG2. Ammonium sulfate induced DNA damage with or without ultraviolet influence was minimal as assessed by the Comet Assay in both cell lines, with a significant difference (p &amp;lt; 0.05) between the treated and negative control samples. These results indicate that the inorganic particulate compound, ammonium nitrate, induced DNA strand breaks at all concentrations and apoptosis at high concentrations in Raji and HepG2 cells, with ultraviolet radiation preventing apoptosis at high concentrations. We hypothesize that ultraviolet radiation inhibits an essential cellular mechanism, possibly involving p53, thereby explaining this phenomenon. Further studies are necessary to characterize the roles of apoptosis inhibition in DNA damage caused by inorganic particulate matter. Citation Format: Michael Xiao, Atif El-Naggar, Albert V. Helsing, Philip M. Lynch, Melissa M. Alegre, Richard A. Robison, Kim L. O'Neill. Mutagenic effects of inorganic particulate matter on Raji and HepG2 cell lines exposed to ultraviolet radiation. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1790. doi:10.1158/1538-7445.AM2013-1790

Kinetics and mechanism of hydrothermally prepared copper oxide nanorod catalyzed decomposition of ammonium nitrate

One of the key aspects in the development of materials science is the synthesis of particles with specific size and morphology for catalytic applications. Nowadays, nanostructured materials with specific morphology are gaining great importance in the field of catalysis. Thin, one-dimensional, monodispersed CuO nanorods with a significantly higher aspect ratio of 5, were successfully prepared by the hydrothermal method with subsequent ultrasonication. The formation of pure monoclinic CuO nanorods was confirmed by powder XRD and SAED. The CuO nanorod growth mechanism is investigated by using TEM and further characterized by FTIR, UV–visible spectroscopy and thermogravimetry. The catalytic decomposition of ammonium nitrate, an environmental friendly rocket propellant oxidizer, over the synthesized CuO nanorods was investigated. The thermal kinetic constants for the catalytic and noncatalytic decomposition of ammonium nitrate samples were computed by using model free (differential and non-linear integral) and model fitting approaches. The catalytic influence was evident even with 1% catalyst concentration. The model fitting method suggested contracting cylinder mechanism as the effective mechanism for all the investigated samples. Apparently, the CuO nanorods provide Lewis acid and/or active metal sites, facilitating the removal of ammonium nitrate decomposition inhibition species such as NH3 and thereby enhance the rate of decomposition.

Forensic analysis of explosives using isotope ratio mass spectrometry (IRMS) — Discrimination of ammonium nitrate sources

An evaluation was undertaken to determine if isotope ratio mass spectrometry (IRMS) could assist in the investigation of complex forensic cases by providing a level of discrimination not achievable utilising traditional forensic techniques. The focus of the research was on ammonium nitrate (AN), a common oxidiser used in improvised explosive mixtures. The potential value of IRMS to attribute Australian AN samples to the manufacturing source was demonstrated through the development of a preliminary AN classification scheme based on nitrogen isotopes. Although the discrimination utilising nitrogen isotopes alone was limited and only relevant to samples from the three Australian manufacturers during the evaluated time period, the classification scheme has potential as an investigative aid. Combining oxygen and hydrogen stable isotope values permitted the differentiation of AN prills from three different Australian manufacturers. Samples from five different overseas sources could be differentiated utilising a combination of the nitrogen, oxygen and hydrogen isotope values. Limited differentiation between Australian and overseas prills was achieved for the samples analysed. The comparison of nitrogen isotope values from intact AN prill samples with those from post-blast AN prill residues highlighted that the nitrogen isotopic composition of the prills was not maintained post-blast; hence, limiting the technique to analysis of un-reacted explosive material.

Isoconversional kinetics of degradation of polyvinylpyrrolidone used as a matrix for ammonium nitrate stabilization

Thermogravimetric analyzer (TGA) has been applied to measure the kinetics of the thermal degradation of virgin polyvinylpyrrolidone (PVP) and a phase stabilized PVP–ammonium nitrate (AN) material. The PVP–AN samples have been prepared by using 20 wt.% of AN and PVP of three different molecular weights. Virgin PVP undergoes a major mass loss in the region 380–550 °C leaving a small amount of nonvolatile residue. The application of an advanced isoconversional method to the respective degradation process demonstrates that its effective activation energy increases from ∼70 kJ mol −1 to a plateau value at 250–300 kJ mol −1, which is independent of the molecular weight. The PVP–AN materials lose spontaneously ∼20% of their mass on heating above the glass transition temperature of the PVP matrix (160–180 °C). After the escape of AN, the remaining PVP matrix degrades in the same temperature region as virgin PVP, however, the effective activation energy of this degradation is ∼150–200 kJ mol −1.

Wettability of Ammonium Nitrate Prills

The wettability of ammonium nitrate (AN) prills is one of the primary factors determining the physical stability and detonation behavior of ANFO. The wettabilities of various types of AN prills were compared using capillary penetration measurements. Complementary characterization studies using scanning electron microscopy (SEM) and thermogravimetry (TG) were performed to rationalize the observed differences in wettability. The wettability of AN was found to be affected by several factors, including surface tension, viscosity, density, and purity of the liquid used, as well as surface composition, porosity, bulk density, particle size, moisture content, and thermal history of the AN samples.

Nitrates in ice: uptake; dielectric response by the layered capacitor method

Ice columns of 0.20–0.25 m length and 0.038 m diameter were grown in the laboratory from dilute solutions (10–5 to 10–2 N) of potassium, sodium, or ammonium nitrate at a constant freezing rate of 0.002 m h–1 and stirring at 300 rpm. The distribution coefficient was computed at ~0.015 m intervals as the ratio of nitrate concentration in the melted ice and in the liquid phase as a function of interface position. The average distribution coefficients were (2.25 ± 0.55) × 10–4 for the potassium and sodium nitrate, and (6.1 ± 1.4) × 10–3 for the ammonium nitrate samples — about a 27-fold increase. These results are in line with other large anions such as sulfate and methanesulfonate that were previously investigated. The dielectric relaxation spectrum of ice slices (~0.012 m thick and sandwiched between thin fluoroplastic foils) was measured between –1 and –85°C at frequencies from 1 Hz to 100 kHz with a lock-in amplifier technique. First, the ice response was recovered from the (Maxwell–Wagner) layered capacitor. The dielectric relaxation ranges were then separated and their characteristic parameters computed. The complex conductivity (Grant plot) and the conductivity frequency-response plot have been the most useful tools for this purpose. Both (alkali-metal and ammonium nitrate) sample groups exhibit the Debye dispersion of polar molecules so characteristic for ice regardless of impurity content. There is also a dispersion range at lower frequencies, and a static or quasi-static conductivity. In the alkali-metal nitrates the low-frequency dispersion is a prominent space-charge dispersion, and the temperature-dependent interaction between orientational and ionic point defects in the ice lattice leads to the conductivity crossover phenomenon. Ammonium greatly reduces the ionic lattice defects responsible for space charge and static conductivity; there is no crossover. Both the Debye dispersion and the crossover support the concept of co-operative responses by the polar molecules making up the ice substance to physico-chemical stimuli. PACS Nos.: 61.72, 77.22G, 77.22J, 81.30F

Ammonium nitrate changes during thermal analysis

A study was made of the difference occurring in ammonium nitrate during investigation by DTA and by DSC. The results show that the DTA of ammonium nitrate (p.a.) is accompanied by the crystal transformation IV → III → II → I and melting. During DSC investigation of the same ammonium nitrate samples, the salt undergoes the transformations IV → III and IV → II in parallel; then follow the crystal transformations III → II → I and melting. The investigation conditions and the history of the samples do not essentially influence the crystal transformations during thermal analysis.